Pfi-253 178
THE CHEMICAL CONVERSION OF SOLID WASTES TO USEFUL
PRODUCTS
OREGON STATE UNIVERSITY
PREPARED FOR
ENVIRONMENTAL PROTECTION AGENCY
APRIL 1974
DISTRIBUTED BY:
TeeJinic&l Efiferasation Sereiss
U. S. DEPARTMENT OF CQftH
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I. RU'ORT NO.
EPA-670/2-74-027
TECHNICAL REPORT DATA
(ricasc rea-V3)
O.S. GOVf.lJiMUKT l'KlHTl!J(i OH'JCr.i 1974 - 717- %«.-/'. Jlfl
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EPA-670/2-74-027
April 1974
THE CHEMICAL CONVERSION OF SOLID WASTES
TO USEFUL PRODUCTS
By
James F. Barbour, Robert R. Groner, and Virgil H. Freed
Department of Agricultural Chemistry
Oregon State University
Corvallis, Oregon 97331
Brant No. EP-R-00242
Program Element No. 1DB314
Project Officer
Charles J. Rogers
Solid and Hazardous Waste Research Laboratory
National Environmental Research Center
Cincinnati, Ohio 45268
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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REVIEW NOTICE
The National Environmental Research Center—
Cincinnati has reviewed this report and approved its
publication. Approval does not signify that the
contents necessarily reflect the views and policies
of the U.S. Environmental Protection Agency, nor
does mention of trade names or commercial products
constitute endorsement or recommendation for use.
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FOREWORD
Man and his environment must be protected from the
adverse effects of pesticides, radiation, noise and other
forms of pollution, and the unwise management of solid
waste. Efforts to protect the environment require a focus
that recognizes the interplay between the components of our
physical environment—air, water, and land. The National
Environmental Research Centers provide this multidisciplinary
focus through programs engaged in
• studies on the effects of environmental contaminants
on man and the biosphere, and
• a search for ways to prevent contamination and to
recycle valuable resources.
As part of these activities, this study describes the
use of solid wastes as raw materials for producing useful
products through the application of chemical and engineering
technology.
A. W. Breidenbach, Ph.D.
Director
National Environmental
Research Center, Cincinnati
111
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TABLE OF CONTENTS
Subject
Introduction
Page
1
Chemical Nature of The Constituents of Solid Wastes 2
Composition 2
Municipal Refuse 2
Industrial Wastes 3
Agricultural Residues 3
Glass 4
Plastics 4
References 22
Tables
II. B. 1. Composition of Typical Municipal Refuse
as Reported by Kaiser 25
II. B. 2. Composition of Municipal Refuse Collected
in Various States as Reported by Hickman... 26
II. B. 3. Industrial Wastes by Categories 27
II. B. 4. Estimate of Industrial Waste
Composition in Oregon 28
II. B. 5. Composition of Poultry Manures 29
II. B. 6. Composition of Manures of
Different Animals 29
II. B. 7. Composition of Cereal Straws 30
II. B. 8. Composition of Grass Seed Straws 31
II. 6. 9. Composition of Some Typical Glasses 32
II. B. 10. Production and Sales of Plastics in 1970... 33
Chemical Nature of Constituents 34
Cellulose 34
Plastics 35
References 37
Figure
II. C. 1. Schematic Diagram of The Cellulose
Molecule 3'J
Tables
II. C. 1. Products of Thermal Decomposition
of Cel lulose 40
II. C. 2. Cellulose Derivatives and Their Uses 41
II. C. 3. Solubility of Some Plastics in
Selected Solvents 42
II. C. 4. Effect of Acids and Bases on Certain
Plastics 43
IV
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Subject
Page
Chemical Processes 44
Crosslinking 44
Chemistry 45
Process 49
Experimental Results 52
References 57
Figures
III. B. 1. Schematic Diagram for Straw
Particleboard Formation 59
III. B. 2. Effect of Wax Removal on Straw
Particleboard Physical Properties 60
III. B. 3. Increased Board Strength Brought About
by Increased Dsnsity 61
III. B. 4. Effect of Pressing Time on
Modulus of Rupture 62
III. B. 5. Increased Board Strength Caused by
Increased Resin Concentration 63
III. B. 6. Relationship Between Density
and Thermal Conductivity 64
III. B. 7. The Relationship Between Pressure
and Density 65
III. B. 8. Showing the Influence of Density on
The Modulus of Elasticity 66
Tables
III. B. 1. Thermal Conductivity of Straw
Particleboard and Other Substances 67
III. B. 2. Physical Properties of Straw
Particleboard 68
III. B. 3. Changes in Weight and Linear Dimension
of Boards Made From Various Materials
When Soaked in Water for 24 Hours 69
Nitrogen and Phosphorus Enrichment 70
Chemistry 70
Process 73
Experimental Results 75
References 80
Figures
III. C. 1. Schematic Diagram of The Nitrogen-
Phosphorus Enrichment Process 81
III. C. 2. The Effect of Reaction Time on Nitrogen
Fixation in the Reaction of Cellulose
and Urea 82
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Subject Page
Figures
III. C. 3. Effect of Reaction Temperature on
Nitrogen Concentration .................... 83
III. C. 4. Effect of Reactant Concentration on
Nitrogen Concentration .................... 84
III. C. 5. Effect of Catalyst Concentration
on Nitrogen Concentration ................. 85
III. C. 6. Effect of Reaction Time on
Phosphorus Concentration .................. 86
III. C. 7. Effect of Reaction Temperature on
Phosphorus Concentration .................. 86
III. C. 8. Effect of Reactant Concentration on
Phosphorus Concentration ................ . . 87
Tables
III. C. 1. Soil Test With Amino Cellulose ............ 88
III. C. 2. Phosphorylation of Straw .................. 89
III. C. 3. Nitrogen and Phosphorus Enrichment
of Straw .................................. 90
III. C. 4. Soil Test With N-Enriched Paper ........... 91
III. C. 5. Soil Test With N and P Enriched Paper ..... 92
Acetylation of Wastes ....................................... 93
Chemistry ............................................... 93
Process ..... ............................................ 95
Experimental Results .................................... 97
References .............................................. 102
Figures
III. D. 1. Schematic of Vapor Phase Acetylation
of Solid Wastes ........................... 103
III. D. 2. Schematic of The Fiber Process of
Acetylation of Solid Wastes ............... 104
III. D. 3. Schematic Diagram of The Solution
Process for Acetylation of Solid Waste.... 105
III. D. 4. Effect of Reaction Time on The
Degree of Acetylation ..................... 106
III. D. 5. Effect of Reaction Time, from 1 to 10
Minutes , on Degree of Acetylation ......... 107
III. D. 6. Effect of Anhydride Concentration on
Acetyl Content ............................ 108
III. D. 7. Showing The Realtionship Between
Catalyst and Degree of Acetylation
When Using Perchloric Acid ................ 109
Hydrogenation of Wastes ....... .............................. 110
Chemistry ............. ................................... 110
VI
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Subject
Page
Experimental Results 113
References 119
Figures
III. E. 1. Gas Train for Analysis of The Head
Gas from the High Pressure Reaction
Apparatus 126
III. E. 2. Carbon Monoxide Analysis System 127
III. E. 3. Gas Chromatographjc - Mass
Spectrometric Analysis System 127
Tables
III. E. 1. Reaction Conditions and Products
of Hydrogenations 128
III. E. 2. Showing the Amounts, in Grams, of Solid
Residue, Oil and Water Produced per Gram
of Cellulose Hydrogenated 129
III. E. 3. Information From Standard Oil Company
Concerning A Sample of Oil From The
Hydrogenation of Waste 130
III. E. 4. Showing the Crudely Determined Material
Balance of The Hydrogenation Reactions.... 131
Etherification 132
Chemistry 132
Experimental Results 133
Discussion 133
References 134
Table
III. F. 1. Some Properties of Methyl and Ethyl
Ethers of Cellulose 135
Oxidation of Cellulose 136
Chemistry 138
Experimental Results 141
Discussion , 142
References 144
Figure
III. G. 1. Showing the Oxygen Comsumption with
Time in The Chromic Acid Oxidation
of 1'ilter Paper 148
Tables
III. G. 1. Per^odate Oxidation 149
III. G. 2. Persulfate Oxidation 150
III. G. 3. Chromic Acid Oxidation 150
Pulping of Straw 151
vn
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Subject
Page
Chemistry 151
Disucssion 152
References 153
Figure
III. H. 1. Showing The Reduced Yield with Increased
Acid Concentration During Nitric
Acid Pulping 154
Tables
III. H. 1. Nitric Acid Pulping of Annual Ryegrass
Straw 155
III. H. 2. Sodium Hydroxide Pulping of Straw 155
Pilot Plant Studies 156
Economic and Engineering Analysis 156
Crosslinking 156
References 162
Figures
IV. B. 1. Block Diagram Showing The Particleboard
Process 163
IV. B. 2. Schematic Diagram Showing The
Straw Particleboard Process 164
Tables
IV. B. 1. Resins Used in The Laboratory Study
of Straw Particleboard 65
IV. B. 2. Estimation of Fixed-Capital
Investment Cost 166
IV. B. 3. Estimation of Total Product Cost 167
viii
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THE CHEMICAL CONVERSION
OF SOLID WASTES
TO USEFUL PRODUCTS
In recent years, the problems associated with solid waste disposal have
become a national crisis. This situation has developed because increasing
amounts of wastes are being produced each year and present waste management
techniques are not adequate to prevent serious environmental pollution.
More wastes are being produced because 1) our population is increasing
and 2) because our per capita rate of waste generation is also increasing.
In 1920, the per capita production of municipal, commercial and industrial
solid wastes was 2.0 pounds per day. By 1969 this figure had risen to
5.3 pounds per person per day. During this same period of time, the
population of the United States had increased from 106 million to 200
million. When agricultural wastes are added, the figures become higher
yet. A study in California reve.ils that an estimated 70 million tons of
solid municipal, industrial and agricultural wastes were generated in 1967,
an average of 20.2 pound per capita per day. Agricultural residues account
for 48.8% of this total, while municipal refuse accounts for 32.0% and the
industrial wastes account for 19.2%.
Over 80% of the solid wastes produced in the nation are disposed of by
open dumping, landfilling, or sanitary landfilling, while about 10% are
incinerated, and the rest are composted, dumped at sea, or disposed of
in other ways.
Although ocean dumping is practiced by many cities located near the
ocean, its practice is being discouraged because of problems associated
with floating debris and destruction of sea life. Several composting
processes have been developed which are capable of converting municipal
refuse to compost, but this technique of waste disposal has not been
successfully adopted because no market for the product has developed.
Incineration is limited to those components of waste which are combust-
ible, however, this process can lead to severe air pollution. The cost of
incineration is high, partly because of the need for air pollution control
equipment.
Landfilling costs are primarily determined by the haul distance and
cost of the land. Leaching from a landfill can pollute surface and sub-
surface water, while anaerobic degradation produces methane gas.
Although none of these management techniques are entirely satisfactory,
at present there is no alternative. One possible alternative is the
utilization of solid wastes as raw materials for the manufacture of useful
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products. This technique would not only reduce the amount of waste
needing disposal, but would conserve our natural resources.
The use of solid wastes as raw materials for the production of useful
products will depend primarily on the successful application of chemical
and engineering technology to waste disposal problems. The objectives
of this study are to 1) identify the chemical nature of the constituents
of solid wastes, 2) investigate transformation processes, and 3) conduct
engineering and economic evaluations of pilot ph-jit operations. The
results of this study will be useful in the development of a Solid Waste
Chemical Transformation Facility, which will be capable of receiving the
wastes produced in a community and disposing of them in an acceptable way.
This report is divided into three sections: Component Chemistry,
Chemical Processing and Pilot Plant Studies. It contains detailed informa-
tion about a few, but does not include an exhaustive evaluation of all
wastes or processes known in this country. This report is designed to be
the foundation for continued study of reutilization processes rather than
the culmination of a research effort.
THE CHEMICAL NATURE OF THE CONSTITUENTS OF SOLID WASTES
Composition
Municipal refuse: Municipal refuse is composed of a vast array of
products which have lo.»t their usefulness and have been discarded. These
waste? include home w.istes, commercial wastes and city wastes. While
home and commercial vastes are usually placed in a rjceptJjle for periodic
removal by a collection agency to a landfill or incinerator, city wastes
usually collect elsewhere and require special handling and disposal.
Home wastes include such diverse products as glass bottles, cans,
plastic toys, cellophane, paper, cardboard, nails, small appliances, tools,
light bulbs, clothes, rubber products, wood, and food items. If these
products are not separated into clashes such as metal, glass, paper, etc.,
in the home, this waste becomes very heterogenous.
Commercial wastes are generated by retail business and institutions
such as hospitals, banks and schools. Although these wastes are alao heter-
ogenous, they contain high percentages of office waste and packaging materials,
City wastes include automobile bodies, large appliances, tires, dead
animals, demolition wastes, street sweepings, crankcase oil and sewage
sludge.
The composition of a s'-.nple of municipal refuse reported by Kaiser
(13), is given in Table II. B. 1. Hickman (8) studied the composition of
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municipal refuse from different states to determine if any wide variations
occur because of geographical location. His results are listed in Table
II. B. 2. Paper and paper products make up the largest single category of
these samples of wastes.
Industrial wastes; Industrial wastes include anything that is pro-
duced by an industrial operation that is not salvaged, sold as a by-
product, or used by another industry as a raw material. Since industrial
firms are designed to prepare specific products from raw materials, the
wastes generated by each industry will vary depending on the nature of
the product and the process.•
The Oregon State Board of Health (22) recently surveyed the industries
operating in Oregon to determine the types of wastes that were being pro-
duced. Table II. B. 3. lists the types of wastes being discarded and
Table II. B. 4. lists the percent by volume being discarded by each industry.
Paper, wood and metals are the most common types of industrial solid waste
being discarded.
Agricultural residues; Agricultural residues include both animal and
crop wastes. Since these wastes come from a wide variety of animals and
crops, no attempt has been made to include a comprehensive list of animal
and crop waste composition, however, representative data from the literature
is included.
Animal Current annual production of animal wastes exceeds that from
wastes any other section of the agricultural-industrial-domestic
complex, with about one-half of the 1.8 billion tons produced annually being
generated in confinement or feeding systems (3).
Although historically, animal wastes have been recycled through the
soil, the advent of inexpensive chemical fertilizers and increased labor
costs have made waste utilization uneconomical. Consequently, wastes
from feed lot operations contribute to problems involving odors, insects,
dust, rodents, stream pollution, nitrification of surface and ground water
resources and eutrophication of surface waters.
The composition of a sample of poultry manure is given in Table II.
B. 5. (31), while a comparison of the fertilizing values of a variety of
manures is given in Table II. B. 6. (2). Animal manures are characterized
by a high percentage of water and a significant concentration of plant
nutrients.
Crop Straw is a solid waste of the cereal and grass seed industries.
wastes While it is tilled into the soil in many areas, some crops,
notably perennials and some soils with a high clay content prohibit the
use of this practice. In some regions, open field burning has been practiced
to sanitize the field and dispose of the straw, however, this practice
contributes to air pollution. The primary obstacle to industrial utiliza-
tion of straw is the cost of harvesting and storing the straw for year
around availability.
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The exact composition of straw depends on a number of factors such
as type, age and climate, but the general composition of most straw is
similar. Rice straw is one notable exception, in that it contains over
twice as much ash as most other straws. The composition of some cereal
straws is listed in Table II. B. 7. (19), and the composition of some grass
seed straws is listed in Table II. B. 8. (29). One can see that cellulose,
lignins and pentosans are the major components of straw.
Glass; Glass products are found in municipal and industrial refuse
and present two problems for waste utilization processes. In milling
operations, glass is very abrasive and can cause excessive wear in metal
parts. One hospital, in Salen, Oregon, now separates glass products prior
to hydropulping their wastes because excessive wear on the impeller had
made their disposal process uneconomical. A second problem encountered
in chemical processing of wastes, is the chemical stability of glass. If
glass is separated and collected in a concentrated form, what are the problems
involved in its reuse in the glass industry?
Recent emphasis has been placed on the possibility of recycling
glass, and collection and delivery systems have been developed in
order to provide the glass industry with a supply of discarded j;*.ass.
Although the technology may be available for the reutilization o: some
glass, one major problem persists: the variations in glass composition.
Each different type of glass, with its unique composition, has its own
uses. Since physical and optical properties are determined by composition,
% heterogeneous mixture of glass may have limited value in a glass
recycling process.
The compositions of several types of glass are listed in Table II.
B. 9. (16). Ihese types are used for such diverse products as windows,
bottles, glasses, vacuum tubos, cookware, chemical apparatus, and safety
glass.
Colored glass contains small amounts of metals or metal oxides not
listed in Table II. B. 9. Rose colored window glass has been produced
by the addition of gold to the melt, yellow-green glass used for metal
sealing is produced by the addition or uranium oxide, deep blue glass is
produced by th? use of cobalt oxide, and green colored fruit jars are pro-
duced by use of iron oxide.
The trade name of a glass is not indicative of its composition, since
nearly 150 different compositions of glass have been marketed under the
trade name of "Pyrex."
Plastics: It has been estimated that plastics make up only 1.3% of
the total annual waste produced in the U.S., however, the plastics industry
is growing. Plastics present a special problem to waste disposal processes,
in that they do not readily decompose in landfills, and some contribute
to air pollution from incineration. It is therefore felt that a review
of the chemical composition of plastics will be helpful in considering
the affect that plastics will have on chemical processes.
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Plastics are polymers which can be molded or shaped. Polymers are
long chain molecules formed by the bonding of smaller molecular units
called monomers:
n A - - »- [A]n
monomer Polymer
If all of the molecules making up the polymers are the same, it is
called a homopolymer, but if two different molecules are used to make
the polymer, it is called a copolymer:
n A + n B - — *» [A - B]n
monomer Polymer
Some polymers are formed by condensation (15:39), that is, a small
molecule is eliminated as the monomer reacts to form the polymer:
n HO - A - OH - »- H[0 - A]n OH + (n - 1)H20
Many plastics are formed from resins which are solids or semi-solids,
composed of a complex, amorphous mixture of organic substances having no
definite melting point and no tendency to crystallize. Thus, cellulose
and its derivatives could not be called resins, even though many of the
esters of cellulose are plastics. Most resins are used in moldings,
laminates and coatings. The use of resins has increased from about 2 million
pounds in 1920 to about 18 billion pounds in 1970, The amounts o ", various
plastics produced and sold in 1970 are listed ait Table II. B. 10. ,.27:66).
Polyethylene constitutes nearly a third of the njastics market while cell-
ulosics, once the leader, comprises only about •.-'->. Capstain (20:25)
reports that there are more than 40 different i. allies of plastics and
sometimes hundreds of individual types in each family. A brief review of
the composition of some of these plastics is presented here.
Polyethylene Polyethylene was discovered in England in the early 1930 's
by a group of chemists who were carrying out high pressure reactions . It
is formed by the polymerization of ethylene:
In the high pressure process (15,000 - 45,000 Ib./sq. in.) ethylene
reacts with itself, in the presence of a catalyst, by a free radical mech-
anism. When this polymer has a low degree of side chain branching, it has
a tendency toward a crystalline structure, leading to a higher melting
point. Its specific gravity ranges from 0.940 - 0.970, and it is called
high density polyethylene. Low density polyethylene, with a specific
gravity range of 0.910 - 0.935, results when side chain branches are
present, producing steric hindrance which also lowers crystallinity,
softening point, and viscosity.
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The polyethylene plastics are non-polar resins which possess a low
dielectric constant. They are used in electrical applications, as coatinga
on cardboard milk and juice cartons, and for containers for such liquids
as milk, juice, detergent and bleach.
Polystyrene Styrene wan first isolated in 1931 during the distillation
of fragrant balsams from certain plants. Although coal tar was the first
commercial source of styrene, today it is produced by the dehydrogenation
of ethylbenzene (21:429):
CH2 " CH3
Fe2°3
650°C
Ethylbenzene Styrene
Purification of styrene is difficult because of its tendency to
polymerize to polystyrene:
Polystyrene
The use of styrene as a monomer began after 1930 when it was dis-
covered that as little as 0.01% divinyl benzenj would produce a brittle
product through crosslinking.
Three styrene copolymers have been developed for utilization because
of their properties. Acrylonitrile-Butadiene-Styrene (ABS) resins are
used because they are tough, rigid and hard. They are used in sewage,
drain and vent piping. Styrene-Acrylonitrile (SA) copolymers are used
with a glass filler for strength. Styrene-Butadiene Rubber (SBR) is used
as a synthetic rubber in automobile tires.
Polyvinyl Vinyl polymers are characterized by the presence of the
chloride vinyl group (Cl^Ct^). When chlorine is attached, the
group becomes vinyl chloride (CH2=CC1}. Polymerization under heat and
pressure with a catalyst produces a linear chain with a molecular weight
between 25,000 and 150,000 times that of the hydrogen molecule:
n CH2 = CHC1
Vinyl Chloride
- CHCl}n
Polyvinyl Chloride
This product is thermoplastic, but long exposure to elevated temp-
eratures results in degradation with subsequent loss of hydrogen chloride
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gas. It has many uses in construction, clothing, electrical, flooring,
home furnishing, packaging, toys, sporting goods, auto mats and seat
covers, credit and playing cards, and paint formulations.
Polyvinyl butyral is used in automobile safety glass laminates and
polyvinyl acetate is used in the manufacture of adhesives.
Phenolics The term "phenolic resin" includes a wide variety of pro-
ducts formed by the reaction of phenolic compounds with various aldehydes,
such as formaldehyde or furfural. These reactions may be acid or base
catalyzed.
The basic catalysts produce a one step reaction from which the resin
is called "resol" type resin. The resol resins have short shelf life
because they continue to react in the storage container and dc not need
additional curing agents:
H2CO
OH-
- CH2OH
Phenol Formaldehyde Methylol phenol
-CH2OH Q
i- CH'
The intermediate of the acid catalyzed reaction is also methylol
phenol:
The two step, acid catalyzed reaction, produces a "novalak" resin,
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which requires additional crosslinkin,? agents such as aldehydes or hexa-
methylene-tetramine for curing when heated. The reaction of the novalak
with the amine is a typical Mannich reaction:
- CH_ - N - H,C -
Phenolic plastics are widely used where heat resistance or electrical
insulation is needed. Phenol -formaldehyde resins are used as binders in
the plywood and particleboard industries.
Polypropylene The polypropylene homopolymer doesn't have a very high-
impact resistance, therefore, much of the polypropylene exists as copolymers.
The monomer reaction is:
H
*• CH. - C
•> i
n H2C = C - CH3
CH,
H
CH,
Propylene
H
I
- CH-CH2 - C = CH2
n-x.
Polypropylene
In order to be useful, polypropylene must contai' iditives such as
antioxidants and ultra-violet light absorbers. These plastics are used
in filament and fibers, transportation equipment, appliances, electrical
wire and cable covering, housewares, luggage and cases, packaging, toys
and novelties.
Amino
Resins
With a suitable catalyst, urea and formaldehyde combine
to form dimethylol-urea (11:1022):
0
a
2 HCHO + H2N - C - NH2
OH'
U"
H
0
"
H
-HO-C-N-C-N-C-OH
II II
H H H H
Formaldehyde Urea
Dimethylolurea
The methylolurea can be combined with polyhydric alcohols by a con-
densation process or with the acetals produced from the initial reaction
of the alcohol and aldehyde.
When an acid catalyst is used, urea and formaldehyde combine to form
methylene urea; which polymerizes into a solid, transparent, brittle,
plastic mass:
0
n HCHO + n H2N - C -
H* ^
8
CH2 - NH - C - NTi
n H20
-------
The properties of this polymer are usually modified by adding wood
flour or some other suitable extender.
Malamine is produced by heating cyanamide (6:156):
3 H2N - C = N
> H2N - C
Cyanamide
Melamine (Cyanuramide)
or by heating dicyandiamide in the presence of anhydrous ammonia and
methyl alcohol (17:245):
3 H,N - C - NH - C 5 N NHV Me°£
2 ||
NH
heat
Di cyanamide
The amino group of melamine then reacts with the formaldehyde molecule
to form the methylol group which takes part in the final polymerization
reaction. Other amines which can be used to make amino plastics include
benzoguanamine, ethyleneurea, thiourea and ana line.
Polyesters One of the earliest polyester resins was of the glyptal
type, which was made from glycerine and phthalic anhydride:
CH2OH
n CHOH
CH2OH
0
II
-C-O-CH -CHOH-CH20 -
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Excess phthalic anhydride serves to crosslink polymer chains:
— C - 0 - CK, - CH - CH.,0- •
To make a resin that is compatable with styrene, an unsaturated
polyester resin can be made by heating a mixture of phthalic anhydride,
maleic anhydride and propylene glycol. By controlling the acidity, and
using an excess of propylene glycol, the polyester formed can be cut
with styrene. The rigidity of the final product is controlled by varying
the ratio of aromatic anhydride to maleic anhydride, or by use of a more
flexible glycol such as diethyl glycol:
II
C
8
I
C
200°
• CH
0
II
0
II
0
II
-CH2-0-C C-0-CH2-C-C-CH=CH-G
2 n
2n
CH2OH
CHOH
I
CH OH
10
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Unsaturated polyester resins have dominated the reinforced plastic
market for many years because they are economical, easily fabricated,
lightly colored and have excellent physical properties. They are used
for body putty, buttons, cultured marble, clay pipe seal, surface coating,
radomes, and boat hulls.
Coumarone Coumarone resins are prepared by the polymerization of a
mixture of benzofuran (coumarone) and indene below 2QfC
using a suitable catalyst such as sulfuric acid. Although
Indene
Resins
the polymerization of coumarone has not been studied extensively, as has
indene, the mechanism involved is probably similar:
Indene
Polyindene
Coumarone
These resins are used primarily in varnishes, rubber products,
linoleum, floor tiles and mastic for flooring.
Alkyd Alkyd resins are formulated from polyesters. An ester is
Resins formed by the reaction of an alcohol with an acid or anhydrid
By selecting a polyfunctional alcohol and a polyfunctional acid, a large
number of repeating units can be formed. If the acid is unsaturated as
with maleic acid or maleic anhydride,
9
8
Maleic Anhydride
/
the resulting esters will be unsaturated. Polyesters are formed by
the addition of an unsaturated monomer such as methacrylate, styrene,
vinyltoluene, or trial lylcyanurate. Although this mixture begins to
react immediately upon contact, the reaction rate is extremely low at
room temperature, so a catalyst is needed. The final product is A
11
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polyester that has been crosslinked at its sites of unsaturation by a
method similar to that used to crosslink the polyenes.
Epoxy Epoxy resins are formed by reacting epichlorohydrin with
a polyhydroxy compound such as bisphenol-A in the presence of a catalyst:
n CIL - CH - CH.C1 + n HO -
V
Epichlorohydrin
Bis-phenol A
- OH
H,C -
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Epoxy resins are used in protective coatings, reinforced plastics,
and bonding and adhesive:; for auto primers and plant maintenance.
Acetal The molecular structure of the acetal plastics is that of
Plastics a linear acetal, made up of chains of unbranched oxymethylene
groups:
- CH2 - 0 - CH2 - 0 - CHH
The resin has high crystallinity and high melting point making it
a suitable replacement for metal in some applications. Gears, foot
valves, bearings, ballcocks, and showerheads have been made from acetal
homo-and co-polymers.
Acrylic Acrylic resins consist of long chain, linear molecules
Plastics formed by the polymerization of acrylic or methacrylic
esters in the presence of a suitable catalyst:
CH2
i
^
1
- C
1
C = 0
1
0
1
CH3
These products are noted for their light transmission, clarity, and
resistance to sunlight and weathering. Modified acrylics have a much
higher impact strength than the general purpose acrylic.
Some of the common trade names for acrylic plastic resins are Lucite,
Crystallite, Plexiglas, and Perspex. They are used for aircraft canopies,
windows, instrument panels, searchlight covers, and aquariums.
The fluorocarbon plastics are analogs of the olefins with
some of the hydrogens replaced by fluorine atoms. The
Fluorocarbon
Plastics
reaction producing the polymer is similar to that used for the other
olefins:
n CF2 = CF2 + n
- CF = CF
Cat..
••CF2 -
- CF - CF2--
CF,
13
-------
These compounds exhibit chemical inertness, resistance to temperature
extremes, essentially no moisture absorption, low coefficient of friction,
low flamnability, and weather and oxidation resistance.
Other similar plastics are the copolymer plastics and the chloro-
fluoro-carbon plastics. These plastics have good electrical, thermal
and chemical properties which give them a wide range of uses. One such
plastic, teflon, is used as a lining on cookware for non-sticking and
greaseless cooking, and in containers for highly corrosive materials.
Polyamide Nylons are polyaciides formed by condensation of dibasic
Plastics anines or by polycondensation of amino acids. Nylon 6/6
(Nylons) is made by condensation of a 6 carbon diamine and a 6 carbon
dibasic acid while nylon 6/10 is formed by condensation of a 6 carbon
diamine and a 10 carbon dibasic acid:
n H2N-(CH2)6-NH2
0 0
II II
HO-C-(CH2)4-C-OH
Hexamethylene diamine Adiptic acid
0 0
n H2N-(CH2)6-NH2 * n HO-C-(CH2)8-C-OH
Sebacic acid
0
n
• NH-(CH2)6-NH-C-(CH2)4-C•+ 2nH20
Nylon 6/6
0
• NH2- (CH2) 6-NH-(i- (CH2) 8-C
2nH,0
Nylon 6/10
Nylon 6 is made by the hydrolysis of e-caprolactam followed by con-
densation.
I ] n H20
n N-(CH2)SC=0 *- n NH2-(CH2)S-C-OH
H
-HiO
0
-•N-(CH2)5-C-
H
e-caprolactam is prepared from cyclohexanonoxime which is produced by
the reaction of hydroxylamine and cyclohexanone. Benzene and phenol,
the byproducts of coke plants, can be converted to cyclohexanone.
14
-------
Copolymers of nylon offer a wide range of properties, while blends
and grafts are used within the plastic industry because they impart
toughness and desirable performance characteristics.
Polycarbonate Polycarbonate plastics are prepared by ester exchange between
Resins dialkylcarbonate and dihydroxyaromatic'compounds or by
phosgenation of a dihydroxyaromatic compound, such as bisphenol A:
n HO-
-OH + n COC12
Phosg
ene
Polycarbonate
2n HC1
Polycarbonates are characterized by high impact strength, dimensional
stability, heat resistance, transparency, and other desirable properties.
They are used for airplane canopies and safety glass lenses where high
impact strength is required.
Silicones Silicones are semi-organic polymers containing silicon,
oxygen, and an organic compound. One method of preparation is to reduce
quartz to silicon and react it with methylchloride. This product is
then hydrolyzed to the polyorganosiloxane:
2 RC1 + Si
Cl -
n Cl -
R
I
Si
I
R
- Cl
n H2o
R
I
Si -
i
R(R
I
••Si
I
R
Cl
- 0- +.'2n 10
Oichlorosilane
Polyorganosilane
The silicones of greatest value are resistant to weathering and oxida-
tion, repellent to water, have good electrical properties, and are incom-
patablo with most organic polymers (can be used as mold releases).
Hydrolysis of the pure dichlorosilanes can give only linear polymers
which are oils or greases (21:605). If trichlorosilanes are hydrolyzed,
15
-------
crosslinking of the chains after hydrolysis produces three dimensional
solid resins:
4n RSiCl3 + 8n
R R
I I
••0-Si-O-Si-h + 12n HC1
I I
OH OH
Trichlorosilane
r
•0
•0
•
R
1
- Si
1
0
- Si
1
R
—
OH
I
- 0 - Si-
1
R
R
1
- 0 - Si-
1
OH
-
m
n
It follows that by changing the proportion of dichloro and trichloro-
silanes present, the properties of the silicone resin produced could be
varied. Other molecules are introduced into the siloxane molecules to
modify the properties of the resin. One of these molecules - fluorine -
has profound effects on the solubility of the silicone compounds. These
fluorinated silicones are insoluble in almost all solvents and can be shown
as: •»
CH,-
CH3
Si - 0-
I
CH3
1
• Si - 0-
l
CH-
I '
CM,
i i
3
CH3
• Si -
CH,
n
CH3
Foam Almost any plastic can be used to form a foam plastic
Plastics (5, 7, 18, 26, 32, 33). Although styrene and polyurethane
foams are probably two of the most widely recognized foams today, cellulosic
foams have been used in the past. Thermosetting plastics such as phenolics
(32) and ureas (7) produce light weight, brittle foams which are good heat-
resistant insulators.
Foams may be rigid, semi-rigid, or flexible and ma; be formed with
16
-------
or without skins. The differences between the normal plastic and a foam
is the density, the residue left in the cells by the blowing agent, and
their uses.
Blowing aeents may be low boiling solvents that evaporate rapidly 'to
caace foaming, or they may be nitrogen containing compounds, such as
azobisformamide, N-nitroso compounds, and sulfonylhydrazides, that decompose
to produce nitrogen. A typical blowing agent is p-toluenesulfonyl semi-
carbazide:
- S - NH - NH - C - NH,
II i
0
One gram of this material produces 143-145 c.c. of gas at standard tempera-
ture and pressure (12). The composition of the gas produced is 62% nitrogen,
30% carbon dioxide, and 4% carbon monoxide (5:27), the non-gaseous products
are toluene disulfide, ammonium sulfinate, and ammonium carbonate.
Another blowing agent, which reacts with water, is sodium azodicarboxylate,
which decomposes to nitrogen in the following way (5:29):
0 o 0
2 NaO - C - N = N - C - 0 Na + 4 II20 - *"» 4 NaO - C - OH * 2 NH2-NH2 + NH2
Sodium Azodicarboxylate
The hydrazine formed can react further if lead peroxide is employed
as the curing agent, as shown by the following equation:
H2N - NH2 + 2 Pb02 - *• N2 + H20 + 2PbO
The lead compounds present are potential health hazards.
Additives Most plastics include some additives which impart desirable
properties to the product allowing a wider range of utilization. Although
most additives are present in very low concentrations, they could affect
the reaction rate or products of chemical processes. A brief description of
some typical additives are given below.
Plasticizers are low melting solids oi" low volatile liquids, very
often esters which impart desirable qualities such as flexibility and
ease in processing to the plastic. Plasticizer molecules mixed with
the plastic weaken the van der Waals forces, usually without reacting
with the polymer.
Plasticizers are chosen with regard for toxicity, odor, heat resistance
and solvent resistance as well as the product flexibility, hardness, flam-
mability and utilization. In addition, "he physical and chemical properties
of a particular plasticizer are important from a standpoint of color, handling,
acidity, moisture content and compatibility with the resin.
17
-------
Some general classes of plasticizers include phthalate esters, adipate
esters, azelate esters, sebacate esters, phosphate esters, epoxy esters,
biphenyls, ether derivatives, glycerol esters, glycol derivatives, petroleum
derivatives (mineral oil, etc.), polyesters, styrene derivatives, sucrose
derivatives, and sUlfonic acid derivatives.
Ultraviolet absorbers are used to reduce polymer degradation caused by
ultraviolet light, with a wavelength between 400 and 290 mu, which has
sufficient energy to break ..most chemical bonds in organic molecules. This
type of degradation results in crazing, color change, decreased strength
and loss of flexibility.
Light energy can be disposed of by the molecule in one or more of the
following ways:
a. emit a photon - fluoresce and return to its original state,
b. give up its energy in the form of heat after distributing the
energy over several bonds,
c. undergo a reversible photochemical change, give off heat, and
return to its original state, and
d. transfer its energy to another molecule. Ultraviolet absorbers
work in two ways to protect the polymers from degradation by UV
light; by absorbing (screening) most of the incident light so the
polymer does not acquire the excited state, and by acting as an
energy transfer agent, absorbing most of the energy from the poly-
mer molecule before it can undergo alteration, thus quenching the
excited state. Most UV stabilizers are screening agents, but
nickel and some of the heavy metals form complexes which act only
as excited state quenches.
Absorbers are selected with regard for their color, compatibility with
the plastic and plasticizer, toxicity, and resistance to water and solvents.
Typical classes of UV absorbers are benzophenones, benzotriazoles,
benzylidene malonates, salicylates, substituted acrylonitriles, organic
nickel, monobenzoates, and indole derivatives. They are usually used in
concentrations of less than 2%.
Colorants are classified as pigments (inorganic and organic ) or dyes.
Pigments are finely divided solids which are dispersed in the system being
colored, while dyes are materials which dissolve in the resin.
Colorants are chosen with regard for cost, hue (red, yellow, blue, etc.),
value (degree of lightness and darkness), chroma (intensity of a distinct
hue, degree of color departure from gray of same lightness), strength
(quantity of color when mixed with titanium dioxide will give a depth of
shade equal to a given weight of some other color mixed with TiC^), and
opacity (the measure of a colorants ability to stop light transmission).
Some colorants, such as the cadmium sulfides, selenides, and cadmium
18
-------
mercury compounds, could prove to be a problem in waste disposal systems
if they became concentrated or leached into the ground water.
Antioxidants are used to combat oxidative degradation during processing,
manufacture, and storage. They must be able to withstand the effects of
heating during processing. In general, heat and light stabilizers are
not antioxidants.
Typical antioxidants are alkylated phenols, alkyiated bisphenols,
alkylidene polyphenols, thio and dithio polyphenols, amines, organic
phosphates, and hydroquinones.
Stabilizers are used to retard the rate of degradation caussd by heat,
light, oxidation, etc. In view of the knowledge of degradation the perfect
stabilizer would be a compound that would screen ultraviolet light, absorb
free radicals, offer oxidation protection, react with resin impurities, and
protect against the disruption of double bonds, however, stabilizers should
not have detrimental effects on the clarivy of the product, be prone to
discoloration, plate out, or be toxic.
Typical stabilizers are barium chloride powders or liquids, barium
cadmium zinc powders or liquids, barium carbonate, barium lead, barium
silicate complexes, calcium powders, some epoxides, nitrogen compounds,
phenols, phosphates, tins and ureas.
Flame retardants, both additive and reactive types, are used to reduce
the hazards to life and property caused by flammable plastics (1, 9, 10,
23, 24, 25, 28 30). Certain chemical agents are known for their ability
to impart flame resistance, including the halogens (chlorine, bromine,
fluorine), phosphorus, and antimony. It is a common practice to use the
halogens in conjunction with phosphorous to formulate flame retardants.
Boron is used to a limited extent because of technical problems related to
compounds containing this element.
Obviously, some resins have inherent flame resistance, such as poly-
vinylchloride and the flurorcarbons, but it is necessary to use flame
retardant additives with most plastics. Some typical flame retardants
are the phosphate esters, chlorinated paraffins, halogenated phosphates,
halogenated aromatics, ammonium bromide, antimony oxide, zinc borate,
bromine containing polyyois, and tetrabromo-bisphenol A.
Fillers and extenders are used for reinforcement, reducing the required
amount of resin to lower the product cost, and to add beauty or strength as
with the addition of marble chips to vinyl flooring. Almost all fillers
give a small amount of reinforcing action when added to polymers. While
most fillers are inert, there is evidence that there may be strong attraction
between some fillers and the functional groups in some resins.
The major types of fillers are:
•a. Silica products such as sand, quartz, or diatomaceous earth, and
pyrogenic silica products such as fumed coloidal silica,
19
-------
b. Silicates including mica, kaolinite, talc, and asbestos, as well
as the synthetic silicates such as calcium and aluminum silicate,
c. Glass in the form of flakes, spheres, fibers and even microballons,
d. Metal oxides such as alumina, magnesia, and titania,
e. Other inorganics such as barium sulfate, silicon carbide and
molybdenum disulfidc,
f. Metals such as bronze, aluminum, lead and stainless steel which
are added primarily for beauty,
g. Carbon black for all types of elastomers and
h. Organic fillers such as wood flour, pulp, etc.
Fiber reinforcement is attained with cellulose fibers, synthetic
fibers, dacron, orlon or nylon, carbon fibers, glass fibers, asbestos
fibers, metallic fibers and ceramic fibers.
Processing aids are used to control viscosity, stabilize an emulsion,
provide lubrication during processing, assist a mold release, prevent
blocking and adhesion, or improve the formation of a filled molding
compound.
The viscosity depressants are not the same as the plasticizers, but
are used to lower the viscostiy of the plastisol without the use of
additional plasticizer. Quite often the compounds will be ethoxylated
fatty acids.
The parting or mold release agents can be sprayed directly on the mold
or incorporated into the plastic itself. Examples are waxes, silicones,
fluorocarbons, and soaps. Their purpose is to prevent the plastic from
sticking to the mold.
Emulsifiers and compounds that help preserve the resin in a heter-
ogenous system of one immiscible liquid dispersed in another. They may
be anionic, cationic, cr non-ionic in nature and in the case of water
emulsions, they could be detergents.
Internal lubricants are somewhat like the mold release agents in that
their raaior function is to prevent the plastic or rubber from sticking to
the processing equipment. Very commonly the internal lubricants are waxes
or metallic soaps.
Anti-blocking agents are designed to prevent two surfaces from per-
manently adhering to each other. These anti-blocking agents must have
partial compatibility and yet exude from the surface under desired con-
ditions to perform their function. Again, the blocking agents are often
waxes, oils, salts of fatty acids, and even polymers.
Silane coupling agents (14) improve the coupling between the inorganic
reinforcement agent and the organic polymer. This is generally carried
out through a chemical reaction or series of chemical reactions. A very
small anuunt of "he right silane will give a large improvement in the
product, especially in the cases where the additives are koalin clays,
silicas, and silicates.
20
-------
Other additives include the peroxides, for generation of free radicals
to crosslink unsaturated compounds; and the anti-static compounds which may
be amines, ammonium compounds or anionic compounds designed to bleed off
static electric charges.
21
-------
References
1. Andrews, W. R., A. D. Cianiolo, E. G. Miller, and W. L. Thompson,
"Plastic Foams as a Flame Penetration Barrier", Journal
of Cellular Plastics. 4(3):102-108 (1968).
2. Benne, E. J., C. R. Hoglund, E. D. Longnecker, and R. L. Cook,
Michigan State University Bulletin 231, Agricultural Experiment
Station, Cooperative Extercion Service, East Lansing, Michigan
1961.
3. Beyer, H. C., "New Developments in Federal Animal Waste Disposal
Programs". Presented at the Animal Waste Disposal Workshop,
Oregon State University, December 2, 1970.
4. Bruins, Paul F., Epoxy Resin Technology, Interscience Publishers,
London, 1969.
5. "Cellular Plastics", Proceedings of a conference, Natick, Massachussets,
April 13-15, 1966; National Academy of Science? Publication 1462,
National Research Council, Washington, D.C., 19o7.
6. Degering, E. F., Organic Chemistry, College Outline Series 6th edition,
Barnes and Noble, Inc., New York, 1958.
7. Ferrigno, T. H., Rigid Plastic Foams, Second edition, Reinhold
Publishing Corporation, New York, 1967.
8. Hickman, H. L. Jr., "Characteristics of Municipal Solid Wastes",
Scrap Age, 26, (February, 1969).
9. Hilado, C. J., P. E. Burgess Jr., and W. R. Proops, "Bromine,
Chlorine, and Phosphorus Compounds as Flame Retardants in
Rigid Urethane Foams", Journal of Cellular Plastics, 4(2),
67-78 (1968).
10. Hilado, C. J., W. C. Kuryla, R. W. McLaughlin, and W. R. Proops,
"Boron and Antimony Compounds as Flame Retardants in Rigid
Polyurethane Foams", Journal of Cellular Plastics, 6(5),
215-220 (1970).
11. Hodgins, T. S., and A. G. Hovey, "Urea-Formaldehyde Film Forming
Compositions", Industrial and Engineering Chemistry,
3£, 9 (1938).
12. Hunter, B. A, and M. J. Kleinfeld, Rubber World, 155(3), 84
(December, 1965).
13. Kaiser, E., "Chemical Analyses of Refuse Components", p. 87,
Proceedings of_ the_ 1966 National Incinerator Conference.
ASME, New York, 1966.
22
-------
14. Kanner, B., and T. G. Decker, "Urethane Foam Formation — Role of
the Silicone Surfactant", Journal of Cellular Plastics,
5(1). 32-39 (1969).
15. Kaufman, M., Giant Molecules, Doubleday Science Series, Doubleday,
Garden City, New York, 1968.
16. KohJ, W. H., Materials Technology for Electron Tubes, p. 4,
Reinhold Publishing Corporation, New York, 1951.
17. Kresser, T. J., Polyolefin Plastics, Van Nostrand Newhold, New York, 1969.
18. Lubitz, H. H., "Minicel Polypropylene Foam", Journal of Cellular
Plastics, 5(4). 37-40 (1968).
19. Miller, D. F., "Composition of Cereal Grains and Forages",
National Academy of Sciences, National Research Council
Publication 285, Washington, D.C., June, 1958.
20. Modern Plastics Encyclopedia 1969-1970, Vol. 46, No. 10A, McGraw-Hill,
Inc., New York, 1969.
21. Noller, C. R., Textbook of Organic Chemistry, 2nd edition, W. B.
Saunders Co., Philadelphia, Pa., 1958.
22. "Industrial Solid Waste Survey, Oregon, 1970", Oregon State Board
of Health, Solid Waste Section, 1970.
23. "arrish, D. B., and R. M. Pruitt, "The Thermal Stability of Flame
Resistant Flexible Urethar.e Foams", Journal of Cellular
Plastics, 5(6), 348-357 (1969).
24. Pitts, J. J., P. J. Scott, and Powell, D. C., 'Thermal Decomposition
of Antimony Oxychloride and Mode of Flame Retardancy",
Journal of Cellular Plastics, 6(1), 35-37 (1970).
25. Pruitt, R. A., "Self Extinguishing Characteristics of Flame Resistant
Flexible Urethane Foam", Journal of Cellular Plastics,
262-266 (1970).
26. Schutz, C. A., "Urea Formaldehyde Foan for Insulation", Journal of
Cellular Plastics, 4(2), 37-40 (1968).
27. "The Statistics for 1970", Modern Plastics, 48(1). 65-71 (1971).
28. Tilley, J. N., H. G. Dadean, H. E. Regmore, P. H. Waszeciak, and
A. A. R. Sayigli, "Thermal Degradative Behavior cf Selected
Urethane Decompositions", Journal of_ Gellular Plastics,
4(2), 56-66 (1968).
29. Unpublished Data from the U.S.D.A. Utilization Laboratory, Albany,
California.
23
-------
30. Way, D. H. and C. J. Hilado, 'The Performance of Rigid Cellular
Plastics in Fire Tests for Industrial Insulation", Journal
of Cellular Plastics, 4(6), 221-228 (1968).
31. Wehunt, K. E., H. L. Fuller, and H. M. Edwards, Jr., 'The Nutritional
Value of Hydrolyzed Poultry Manure for Broiler Chicks", University
of Georgia Agricultural Experiment Station, Journal Paper
No. 114, 1960.
32. Wheatley, S. J., and A. J. Mullett, "Foam Plastic Insulation for
High Temperature and Shock Protection", Journal of Cellular
Plastics, 6(3), 112-118 (1970).
33. Woolard, D. C., "Expandable ABS", Journal of Cellular Plastics,
4(2), 16-21 (1921).
24
-------
Table II. B. 1. Composition of Typical Municipal Refuse as Reported by
Kaiser (13).
Category
Paper
Corrugated paper boxes
Newspaper
Magazine paper
Brown paper
Mail
Paper food cartons
Tissue paper
Wax cartons
Plastic coated paper
Moisture
Garbage
Vegetable food wastes
Citrus rinds 6 seeds
Meat scraps, cooked
Fried fats
Glass, Ceramics, Ash
Vegetation
Ripe tree leaves
Flower garden plants
Lawn grass green
Evergreen
Metals
Miscellaneous
Wood
Plastics
Rags
Leather goods
Rubber compositoon
Paint and oils
Vacuum cleaner catch
Dirt
Total
Weight Percent
23.38
9.40
6.80
5.57
2.75
2.06
1.98
0.26
0.76
2.29
1.53
2.29
2.29
2.29
1.53
1.53
1.53
2.29
0.76
0.76
0,38
0.38
0.76
0.76
1.53
53.46
9.05
8.40
7.73
6.85
7.62
99.90
25
-------
Table II. B. 2. Composition of Municipal Wastes
Collected in Various States as Reported by Hickman (8).
wt.% (wet basis)
CALIFORNIA NEW JERSEY TENNESSEE ARIZONA ILLINOIS OHIO NEW YORK
Paper
Food
Metal
Glass
Wood
Misc.
54
15
7
2
2
2
51
10
8
4
4
4
46
26
11
11
1
5
43
22
10
8
2
1
42
14
9
6
-
—
42
28
9
8
3
3
40
10
8
-
7
3
26
-------
Tabia II. B. 3. Industrial Wastes by Categories
Rubber-Plastics
Shredded rubber
Tires
Foam Rubber
Plastic wastes
Fiberglass wastes
Rubber Scraps
Mixed Sludges
Treatment plant
sludge
Lagoon sludge
Settling basin
sludge
Fruit -Vegetable
Wastes
Fruit wastes
Vegetable wastes
Dough wastes
Grain wastes
Glass Wastes
Glass bottles
Paper Waste
Corrugated
Paper bags
Paper drums
Office waste
Cafeteria waste
Washroom waste
Wood Waste
Bark
Lumber
Pallets
Sawdust
Sanding dust
Wooden crates
Wooden boxes
Trimmings
Skids
Sand and Stone
Wastes
Bricks
Tailings
Tiles
Sand
Concrete
Ashes
Metal Wastes
Banding
Strapping
Metal Scraps
Buckets
Barrels
Cans
Wire
Turnings
Burnings
Slag
Animal Wastes
Animal offal
Hair
Feathers
Hides
Leather scrap
Bones
Shells
Paunch
Fish
Seafood
Petro-Chemical
Wastes
Waste Inks
Paints
Oils
Solvents
Thinner
Resins
Glues
Asphalt
Pesticides
Herbicides
Textile Wastes
Rags
Upholstery scrap:
Drapery scraps
Apparel scraps
Canvas § burlap
Cotton 5 wool
Textile bags
27
-------
Table II. B. 4. Estimate of Industrial Waste Composition in Oregon
Volume Percent
to
oo
Meat Processing
Electric Machinery
Dairy Products
Misc. Food Processes
Printing 5 Publication
Petroleum 5 Allied
Scientific Instrument
Ordnance
Non-Elec. Machinery
Processed Foods
Apparel Products
Rubber 5 Plastics
Chemical § Allied
Transportation
Misc. Manufacturing
Cannery § Frozen
Textile Mills
Furniture
Stone, Clay 5 Glass
Seafood Processing
Fabricated Metals
Primary Metals
Wood Products
Paper & Allied
Leather Manufacture
Paper
Waste
97
97
96
94
94
92
88
85
82
70
69
69
60
58
57
56
54
52
44
43
43
30
27
25
14
Wood
Waste
3
1
>1
1
4
5
5
11
13
>1
1
13
27
40
3
2
39
40
13
43
7
65
4
2
Metal
Waste
>1
1
1
1
3
5
1
1
8
1
2
1
4
5
10
14
15
6
1
4
Animal Textile Petro-
Waste Waste Chemcl
Fruit Rubber Sand, stn
Vegtbl Plastic Glass, Ash
1
3
>1
28
1
42
3
23
39
33
72
>3
2
2
1
16
43
1
1
1
3
11
47
-------
Table II. B. 5. Composition of Poultry Manures
wt.% (air dry basis)
Hen Manure Broiler Manure
Moisture 4.29
Ash 23.28 20.83
Crude Fiber 12.15
Ether Extract 1.38
Crude Protein 19.94 32.21
True Protein 10.13 11.42
Calcium 6.50 S.50
Table II. B. 6. Composition of Manures of Different Animals
wt.%
Water Nitrogen Phosphorus Potassium
Chicken 54 1.56 0.40 0.35
Dairy cattle 79 0.56 0.10 0.50
Fattening cattle 80 0.70 0.20 0.45
Hog 75 0.50 0.14 0.38
Horse 60 0.69 0.10 0.60
Sheep 65 1.40 0.21 1.00
29
-------
Table II. B. 7. Composition of Cereal Straws
wt.%, dry basis
Component
Dry matter
Cellulose
Lignin
Pentosans
Crude protein
Crude fat
Crude fiber
Ash
Sulfur
Sodium
Chlorine
Calcium
Phosphorus
Potassium
Magnesium
Iron
Oat
rain. - max.
\
83.9 -
40.1
13.4 -
2.0 -
0.8 -
33.3 -
4.9 -
0.20 -
0.23 -
0.70 -
0.13 -
0.15 -
0.20 -
0.16 -
0.018-
95.2
15.8
8.6
3.2
54.0
12.9
0.27
0.53
0.85
0.40
0.43
2.41
1.43
0.056
Rice
min. - max.
38.8
17.7
2.8
8.7
27.6
14.0
\
0.31
O.lr
0.06
1.10
0.07
- 93.4
- 6.2
- 2.3
- 38.3
- 20.1
- 0.38
- 0.15
- 1.51
- 0.18
Wheat
min. - max.
82.8 -
35.3 -
12.4 -
1C. 2 -
1.5 -
1.0 -
36.4 -
3.5 -
0.13 -
0.06 -
0.21 -
0.10 -
0.04 -
0.12 -
0.05 -
0.007-
99.1
63.9
15.1
12.8
6.9
3.7
51.5
11.1
0.29
0.23
0.34
0.42
0.51
1.95
0.70
0.017
30
-------
Table II. B, 8. Composition of Grass Seed Straws
wt.%, dry basis
Fine Chewings Merion Highland Perennial Annual
Component Fescue Bluegrass Bentgrass Ryegrass Ryegrass
Crude protein
Crude fiber
Crude fat
Crude pectin
Ash
Total sugars
Reducing sugars
Pentosans
Lignin
Cellulose
5.2
45.1
1.8
1.1
7.0
0.20
0.17
27.1
10.2
45.2
9.1
36.6
2.1
1.6
5.4
2.49
1.74
24.0
8.7
41.6
4.6
39.4
1.9
1.7
2.7
2.01
0.96
24.8
9.0
44.2
5.5
41.2
1.8
2.3
6.7
0.68
0.43
22.0
8.8
42.3
4.5
40.2
1.4
1.8
6.6
4.05
3.25
23.7
8.6
42.8
31
-------
Table II. B. 9. Composition of Some Typical Glasses.
Wt%
TYPE
Soft Soda
Lead
Borosilicate
Special
Extra Hard
1
2
3
'A.
5
6
7
8
9
10
11
12
13
Sl
70
69
69
73
56
57
63
71
30
73
22
54
58
°2
.5
.3
.6
.5
.1
.5
.6
.5
.7
B2°2 A1
1
4
3
1.2
1
1
0
13.7 7
12.9 2
16.5
37 23
7.4 21
3 22
2°2 Pb°
.8
.1
.5 29
.5 29.4
.28 20.22
.4
.2
6
.7
.1
.4
C 0
N T
CaO
6
5
5
5
0
0
0
0
10
13
5
.7
.8
.6
.37
.2
.2
.94
.3
.5
.9
E N T
Na2°
16
17
16
17
5
4
7
5
3
6
1
.7
.5
.8
.23
.6
.1
.6
.3
.8
4.5
.5
.1
K20
0.8
1.9
0.6
6.6
7.3
5.54
2.4
0.4
0.2
0.2
MgO BaO Ma2°3
3.4
1.6
3.4
3.67
0.6
0.4
0.88
3.5
8.4
-------
Table II. B. 10. Production and Sales of Plastics in 1970
Plastic
Polyethylene, low density
Polystyrene ft copolymers
Polyvinylchloride § copolymers
Polyethylene, high density
Phenolic?
Polypropylene
Urea and Melamine
All other vinyls
Polyesters
Alkyds
Coumarone-indeme
Cellulosics
Epoxy
Miscellaneous
Total
Production
4300
3350
3150
^
1700
1075
1010
710
650
645
604
340
180
165
1722
19600
Sales
4180
3323
3050
1625
888
985
638
600
613
300
350
175
155
1618
18500
33
-------
Chemical Nature of the Constituents
Cellulose. Cellulose is a polysaccharide which yields only glucose
upon hydrolysis. There is general agreement among workers in the field
that cellulose is composed predominately of 3 1,4 linked D-glycopyranose
units, Figure II. C. 1.
The reactions of cellulose resemble those of the simple sugars. Since,
however, all but one of the potential reducing groups of the glucose residue
(the one terminating unit of the open chain) are involved in glycosidic link-
ages between individual members of the chain, cellulose lacks the pronounced
reducing power of most of the sugars. The chief reactions of cellulose are
those of its hydroxyl groups.
All glucose residues except one (the other terminating unit) possess three
free hydroxyl groups, the one in the C-6 position being of primary nature and
those in the C-2 position and the C-3 position being of secondary nature.
These free hydroxyl groups react as alcohols to form addition compounds
with alkalies and certain complex salts. Under certain conditions they also
react with sodium metal to form compounds (comparable to the alcoholates)
called cellulosates. Furthermore, the hydroxyl groups of cellulose react
to form esters and ethers, and on oxidation are converted stepwise into
carbonyl and carboxylic groups.
The reaction product of cellulose and sodium hydroxide, called alkali
cellulose, is used in the production of cellulose xanthate and cellulose ethers.
A variety of cellulose ethers can be prepared by reacting alkali cellulose with
various alkyl chlorides. Similarly a variety of cellulose esters can be pre-
pared by reacting cellulose with various organic acid anhydrides.
Acid hydrolysis of cellulose produces glucose which can be converted to
hexsne by reduction with hydrogen iodide and red phosphorus or to sorbitol by
reduction with sodium amalgam.
Cellulose can be degraded both thermally and chemically. The main products
of thermal decomposition are carbon, carbon dioxide, and water. Some of the
other products formed are acetic acid, acetone, formic acid, formaldehyde,
•furfural, hydroxymethylfurfural, ethene, carbon monoxide, and methane. A
summary of the quantity of products produced by the thermal decomposition of
cellulose (9^ ;ire listed in Table II. C. 1.
The er.d product of the hydrolysis of cellulose is glucose, but continued
chemical action on the glucose results in the formation of hydroxymethylfurfure
which produces levulinic acid and formic acid. Oxalic acid can be produced
from cellulose by alkaline oxidation (5) or nitric acid oxidation (15). Under
some conditions the alkaline degradation of cellulose can result in complex
fragmentation reactions producing formic, ace;tic, glycolic, and lactic acids
(16).
Cellulose derivatives are used for a variety of purpoi.es. Some of the
uses of cellulose derivatives are listed in Table II. C. 2.
34
-------
Plastics. Most plastics are generally chemically inert, however, each is
affected to some degree by certain organic solvents, acids, and bases. In
addition, all plastics degrade at elevated temperatures.
The solubility of some plastics in organic solvents is listed in Table
II. C. 3. The plastics which appear to be most resistant to attack by
solvents are the nylons, urethanes, polyethylene, fluorocarbons, and chlorinated
polyethers.
The effect of acids and bases on certain plastics is listed in Table
II. C. 4.
As with wood, paper, or other combustible materials, at elevated temp-
eratures, plastics degrade to form combustible gases, non-combustible gases,
and a char. If an oxidizing agent is present, the combustible gases will
burn when heated above their ignition point. However, in the case of halogenated
or flame retardant treated plastics the combustibility of the plastic is nil
unless the temperature is raised much higher than the normal combustion temp-
erature. The halogenated plastics produce acid gases such as hydrogen chloride.
The urethane plastics show a great variation in properties. Urethane foam
from tertiary alcohols may decompose at a temperature as low as 50CC, while
urethanes of many primary alcohols change only slowly at 150°C. According to
Saunders (2:127) there are essentially three types of reactions that can take
place during the thermal decomposition of urethane:
1) a dissociation to alcohol and isocyanate,
0
R - NH - C - OR' *• R'OH + R-N = C = 0
2) formation of a primary amine and an olefin, and
q
R - NH - fc - 0 - CH2 - CH2R' »- RNH2 + C02 + R1 - CH = CH2
3) secondary amine formation.
RNH - C - OR *• R - NH - R + CO,
The two reactions likely to occur with isocyanates at elevated temperature are
the formation of the carbodiimide and trimerization to an isocyanate.
35
-------
2R-N =
R - N = C = 0
RN = C = NR + C02
Carbodiimide
9
R - N
I
C
- R
Isocyanurate
When polyethylene is pyrolyzed (4) at 300 and SOO°C in oxygen and wet
or dry carbor. dioxide, the products contain carbon dioxide, carbon monoxide,
hydrogen, saturated and unsaturated aliphatic hydrocarbons, benzene, toluene,
and polycyclic aromatic compounds.
The pyrolysis (not combustion) of polyvinyl chloride (8) produces hydrogen
chloride, saturated and unsaturated aliphatic hydrocarbons, methyl and ethyl
chlorides, and aromatic compounds.
Other studies of the products of plastic degradation have been conducted
by Cerceo (3), Way and Hilado (14), Pruitt (12), Pape, et al. (10), Parish
and Pruitt (11), and others (1, 6, 7).
36
-------
References
1. Andrews, W. R., A. D. Cianiolo, E. G. Miller, and W. L. Thompson,
"Plastic Foams as a Flame Penetration Barrier," Journal o£
Cellular Plastics, 4(5). 102-108 (1968).
2. "Cellular Plastics," Proceedings of a Conference, Natick Massachusetts,
April 13-15, 1966. Publication 1462, National Academy of Sciences,
National Research Council, Washington, D.C., 1967.
3. Cerceo, E., "Effect of Time on the Infrared Spectra of Epoxy Pyrolyzates,'
Industrial and Engineering Chemistry, Product Research and Develop-
ment, 9_, 96-100 (1970).
4. Chaigneau, M., and G. LeMoan, "Pyrolysis of Plastic Materials. IV.
Polyethylene," Annales Phannaceutiques Francaises, 28(6),
417-423 (1970).
5. Heuser, E., The Chemistry of Cellulose, p. 490, John Wiley and Sons
Inc., London, 1944.
6. Hilado, C. J., P. E. Burgess, Jr., and W. R. Proops, "Bromine, Chlorine,
and Phosphorus Compounds as Flame Retardants in Rigid Urethane
Foams," Journal of Cellular Plastics, 4(2), 67-78 (1968).
7. Hilado, C. J., W. C. Kuryla, R. W. Mclaughlin, and W. R. Proops,
"Boron and Antimony Compounds as Flame Retardants in Rigid
Polyurethane Foams," Journal of Cellular Plastics, 6(5),
215-220 (1970).
8. LeMoan, G., and M. Chaigneau, "Pyrolysis of Materials in Plastics. I.
Polyvinyl Chloride (PVC). Characterization of Possible Volatile
Toxic Compounds," Annales Phannaceutiques Francaises,' 27(2) 97-
101 (1969).
9. Nikitin, N. I., The Chemistry of Cellulose and Wood, Translated by
J. Schmorak, Israel Program for Scientific Translations,
Jerusalem, 1966.
10. Pape, P. G., J. E. Sanger, and R. G. Nametz, "Tetrabromophthalic
Anhydride in Flame Retardant Urethane Foams," Journal of
Cellular Plastics, 4(11), 438-442 (1968).
11. Parrish, D. B., and R. M. Pruitt, "The Thermal Stability of Flame
Resistant Flexible Urethane Foams," Journal of Cellular
Plastics. 5(6), 348-357 (1966).
37
-------
12. Pruitt, R. M. "Self-Extinguishing Characteristics of FJame Resistant
Flexible Urethane Foam," Journal of_ Cellular Plastics, 6(6),
262-266 (1970).
13.- Tilley, J. N., H. G. Nadeau, H. E. Reymore, P. H. Waszliciak, and
A. A. R. Sayigh, "Thermal Degradative Behavior of Selected
Urethane Foams," Journal of Cellular Plastics, 4(2), 56-66 (1968)
14. Way, D. H., and C. J. Hilado, "The Performance of Rigid Cellular
Plastics in Fire Tests for Industrial Insulation," Journal
Of Cellular Plastics, 4J6J_, 221-228 (1968).
IE. Webber, H. A., "The Production of Oxalic Acid from Cellulosic
Agricultural Materials," Iowa Engineering Experiment Station
Bulletin 118, Iowa State University, Ames, Iowa, 1934.
16. Whistler, R. L. editor, "Cellulose" Volume III, p. 161, Methods
in_ Carbohydrate Chemistry, Academic Press, New York, 1963.
38
-------
H-C-H
c-
1/&
/\9H
HO C-
I
H
*0
H),
•c
I
OH
OH
1
H-C-H
H
1
A P —
/ \ /\
' \ /OH
C
c —
1
H-C-H
1
OH
OH
1
-C
«\r
A
•c o
.
\
r
1
1
£— •
/H
>
\°,H
c —
1
H
-o
y
Hv/H
-c
i
OH
H
I
0 C
\/OH
H\H
c —
1
H-C-H
1
OH
n
OH
I
-C
«\'
/\
•0 OH
Figure II. C. 1. Schematic Diagram of a Cellulose Molecule.
-------
Table II. C. 1. Products of Thermal Decomposition of Cellulose
Cotton Pine Pulp Spruce Pulp Birch Pulp
carbon 38.8 36.9 34.9 33.4
carbon dioxide 10.4 12.8 11.9 11.1
ethene 0.2 0.2 0.2 0.4
carbon monoxide 4.2 3.4 3.9 3.5
methane 0.3 0.3 0.2 0.5
methanol 0.0 0.0 0.1 0.0
acetone 0.1 0.1 0.1 0.2
acetic acid 1.4 2.2 2.8 3.9
other organic comp. 5.1 4.2 8.5 7.7
tar 4.2 4.8 6.3 9.6
water 34.5 34.2 30.0 29.4
40
-------
Table II. C. 2. Cellulose Derivatives and Their Uses
Compound
ethyl cellulose
methyl cellulose
sodium carboxymethyl cellulose
benzyl cellulose
ethyl hydroxyethyl cellulose
cellulose nitrate
sodium cellulose sulphate
cellulose acetate
cellulose xanthate
Uses
plastics, lacquers, sheeting,
varnishes, adhesives.
adhesives, latexes, emulsions,
foods, sheeting, cosmetics,
Pharmaceuticals.
colloid, thickener.
coatings, plastics, lacquers.
emulsifier, thickener,
stabilizer.
lacquer, plastic, explosives.
gelatin films, glues, paints,
textiles, sizing, paper,
coating.
yarn, photographic films,
sheeting, plastics, coatings
membrane.
fiber, cellophane, plastics,
sponges.
41
-------
Table II. C. 3. Solubility of Some Plastics in Selected Solvents.
Methanol
Ethanol
i-Propanol
n-Propanol
sec-Butanol
n-Butanol
Methyl -isocutyl carbinol
Ethylene glycol
Monoethyl Ether
Ethylene glycol
Monobutyl ether
Acetone
Ethylene glycol monoethyl
Ether Acetate
Methyl Ethyl Ketone
Ethyl Acetate
iso-Propyl Acetate
sec-Butyl Acetate
n-Propyl Acetate
Methyl-i-Butyl Ketone
n- Butyl Acetate
n-Amyl Acetate
Ethyl Ether
Methyl Amyl Acetate
Hexyl Acetate
Isophorone
Benzene
n-Hcptane
Toluene
Xylene
Chlorinated Hydrocarbons
zct>T3>*o>nnm -nponoT3ms<<-l->-ceH-O
PXP rtOH-AH-H- HOrt t— »—»-• o
3 X M 3*n33A32O*-X OS > D O G D A
A 0* XPPAP-P03C^ 2CO3'V'UIA>-
O (--Hit rt p. A O* A A-tAH-AAi—l-'
3 AO*A<>(DI-"IH-3 rtXrtO >- C
p 3OP.H-nO'>-hi->Ci—
rt A3 3 H H-3 PprtH-noi-O
A T3X XPOAP.13 OI—AO-AAOI/I
O !-• h- C O- A 3* H A rf rt Ul A
t-pCTSA X PPA
X > rt 0* > A 3 t- >rtrt
AOAA>-- O P OAA
r» « u> H «• !-• rt Ai
3* rt X H- A rt 03
A P ft. O PC
H rt rt rt
A AX
H
n P
O rt
•a A
o
•s
A
JO PO
A A
I/I VI
H- !-••
W Ul
rt rt
P P
3 3
rt rt
rt rt .
0 0
a a
o o
w ui
rt rt
rt
<0
0
tX>
O
H'
O
p
o
H-
P.
X
X
X
X
A
rt
H
CD
5-
**<
P.
o
p
tJ
rf
P
x tr
o
X <
X
00
x o
o
x n
x
x
x
X
X
X
X
X X
50 jo
A A
I/I U)
(J. H.
VI Ul
rt rt
P P
y §
rt rt
rt rt
0 0
3 9
VI Ul
rt rt
•
X
X X
X
X
X X
X X
X X
X X
X
X
X
X
X X
XXX
X X
X X
X X
X
\J V
^\ r*
X X
XXX
X X
XXX
XXX
XXX
XXX
XXX
XXX
X
XXX
XXX
XXX
X X
X X
X X
X
X
X
X
X
X
X
X
X
X
X X
X X
X
X
X
X
X
X
X
XXX
X
X
X
X
XXX
X X
XXX
XXX
X
X X
X X
X X
X X
X X
X X
X X
XXX
X
X
X X
X
X
X
X
X
X X
X X
XXX
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X
X
XXX
X
X
X
42
-------
Table II. C. 4. Effect of Acids and Bases on Certain Plastics.
Plastics
Polypropylene
Polystyrene
Polycarbonate
Pherroxy
Vinyl Butyral
Polyvinyl dichloride
Urethane Elastomers
Acetal
Acrylic
Ethyl Cellulose
Cellulose Acetate
Chlorinated Polyether
Fluorocarbons
Nylons
Polyethylene
Diallyl Phthalate
Furan
Melamine FormaJdehyde
Phenol -Formaldehyde
Polyacrylic ester
Polyesters
Silicons
Urea-formaldehyde
Epoxy Cast Resins
Aliyl Res in
Phenol :s
weak
acids
resistant
none
none
none
slight
none
dissolves
resistant
slight
slight
slight
none
none
resistant
resistant
none
none
none
slight
swells
slight
none
slight
none
none
none
strong
acids
attacked
resistant
slight
none
dissolves
attacked
decomposes
decomposes
none
attacked
slight
decomposes
swells
attacked
slight
decomposed
attacked
slight
Effect of
oxidizing
acids
attacked
attacked
attacked
attacked
attacked
attacked
decomposed
attacked
decomposed
weak
alkalies
none
none
limited
resistance
resistant
slight
none
dissolves
resistant
slight
none
slight
none
none
none
resistant
none
none
none
slight
swells
attacked
none
slight
none
none
slight
strong
alkalies
resistant
none
attacked
resistant
slight
none
dissolves
resistant
slight
slight
decomposes
none
none
none
resistant
slight
slight
attacked
decomposes
swells
attacked
slight
decomposed
slight
none
decomposes
-------
CHEMICAL PROCESSES
As indicated earlier, cellulose is the single component that appears
in the greatest amounts in most solid wastes. The reactions reported
herein are primarily reactions involving cellulose because reclaiming and •
veuse of this cellulose would remove about half of the solid waste disposed
c' annually.
Of the many reactions possible with cellulose the primary groupings
studied are crosslinking, nitrogen and phosphorus enrichment, esterification,
hydrogenation, etherification, oxidation, and pulping.
The process which shows the greatest potential and will be persued to
finish first is crosslinking. Crosslinking can help solve two problems at
once: The disposal-reutilization of solid waste, and shortage of satisfactory
building materials.
Hydrogenation is probably not economically feasible at present,
however, with the rapidly dwindling petroleum supplies this may soon
become not only economical, but essential.
Nitrogen and phosphorus enrichment would allow the waste to be returned
to the soil as a combination soil conditioner and fertilizer. Composting
alone, does not give a product that has appeal to the market because of
the lack of plant growth stimulants.
Esterification and etherification lead primarily to plastics. Cellulose
plastics are at present being replaced by the petro-chemical plastics, and
therefore are a waning market. One new field that may require more
cellulose is reverse osmosis, used in purifying water.
The products of partial oxidation may have great potential, but the
time required to produce dialdehyde cellulose is so great that the economics
of this process appear unsatisfactory.
Pulping may be developing again. Our dwindling forests, new pulping
methods, and new straw storage methods may overcome the economic barriers
that have blocked the use of straw for pulping. Reclaiming paper and adding
straw pulp could greatly reduce the demands on our forests and alleviate
air pollution at the same time.
Crosslinking
Since cellulose is a polymer containing chemically active hydroxyl groups,
crosslinking between chains should be one means of producing a solid material.
The crosslinking agents would have to be polyfunctional compounds capable of
uniting with the cellulose hydroxyls of more than one cellulose chain. The
fabric industry has evaluated the use of polycarboxylic acids, such as succinic
acid, oxalic acid, and citric acid, to crosslink cotton cloth for improvement
44
-------
of its properties (4). Crosslinking may also be possible with an alkyl dihalide,
resulting in ether linkages, but no known experimentation has been attempted.
A third possibility for crosslinking involves use of isocyanates, which react
with hydroxyls to produce carbamate esters. This reaction is the basis for
rigid and soft polyurethane foam using liquid polyls. The reaction of
cellulose with isocyanates has been studied by Schnecbeli (14), Ellzey (6),
and Hobart (11).
A variety of cellulosic wastes can be used to make a solid board using isocya-
nate resins including wood, straw, and paper, and although each of these wastes
has been used in the laboratory to prepare small samples, extensive testing has
been accomplished only with straw particleboards. Therefore this report will
primarily show results achieved with straw.
Chemistry: An isocyanate compound contains the functional group
-N=C=0 (-NCO), while diisocyanates contain two functional groups per molecule
and polyisocyanates contain many functional groups on a long chain resin.
In order to achieve crosslinking between two cellulose molecules, at least
two functional groups per molecule are required.
Isocyanates react with compounds which contain an active hydrogen such as
alcohols, phenols, amines, amides, ureas, acids, and water. These reactions
ordinarily take place without catalysts or high temperatures (3), but
catalysts may be required when steric hindrance is a factor.
A brief review of isocyanate chemistry is presented here. More detailed
information about the synthesis and use of isocyanates is reported by
Saunders and Slocombe (13).
Aromatic isocyanates are usually more reactive than aliphatic isocyanates
(3), and electronegative groups on the aromatic ring enhances reactivity,
while electropositive groups reduce the reactivity.
Reactions Water will react with isocyanates (I) as shown in Reaction
T:fk=alkyl or aryl group)
• RNHCOOH •»• RNH2 + COj [1]
II III
RNCO •*• RNH-CO-HNR [2]
I IV
The carbamic acid (II) that is formed decomposes readily to produce an
amine (III) and carbon dioxide. If a base is present, this reaction will
proceed no further; however, in the absence of a base, the amine (III) will
react with the isocyanate (I) to form a substituted urea (IV) as shown in
reaction 2.
45
-------
The rate of reaction of isocyanates with water depends on the particular
isocyanate involved, for example octadecyl isocyanate can be emulsified
and will be stable for as much as a day while others react much more readily.
Alcohols will react with isocyanates (I) as shown in reaction 3:
R-NCO + R'OH •*• R NHC 0 OR1 [3]
I V VI
The carbamate ester (VI) which is formed is sometimes called
a urethane. The reaction of primary alcohols is fairly rapid but
tertiary butyl alcohols react slowly, probably due to steric hindrance,
and must be catalyzed. Phenolic compounds react as aromatic alcohols, but
their reaction rates with isocyanates are extremely slow and must be
catalyzed.
Halogen, acids (VII) react with isocyanates as shown in reaction 4:
(x is a halogen)
RNCO + HX * RNH-COX [4]
I VII VIII
This reversible reaction produces a monosubstituted carbamyl halide (VIII),
which is stable at room temperature but not at. elevated temperatures.
The reaction between isocyanates (I) and organic acids (IX) is shown in
reaction 5:
RNCO + R'COOH -*• RNHCOOCOR1 [5]
I IX X
The anhydride (X) which is formed decomposes to form an amide (XI) and
carbon dioxide as shown in reaction 6:
RNHCOOCOR' + RNHCOR' + C02 [6]
X XI
Cellulose should react with isocyanates because of the three hydroxyl
groups on each anhydroglucose unit, however Bayer (2) speculated that
cellulose would not react with isocyanates because of the "water of
crystallization" left in carefully dried cellulose. He theorized that only
substituted ureas would be present in the reaction mixture.
More recently, however, Hearon, et. al. (8,9), studied the reaction
of aliphatic and aromatic isocyanates with dried cellulose and cellulose
acetate, and found that the acetate groups could be removed by hydros/sis,
and the resulting cellulose carbamate was soluble in organic solvents.
46
-------
In addition, the isocyanate-cellulose reaction has been studied by
Hearon and Lobsitz (10), Schneebeli (14), Eckert (5), Ellzey (7), Hobart
(11), and Volozhin (15). llearon and Lobsitz studied the aryl carbamates
of cellulose including chlorophenyl carbamate and reported that the completely
carbamylated product is soluble in a variety of organic solvents, but not
in methanol or ethanol. Schneebeli studied the reaction of phenyl
isocyanate, in anhydrous pyridine, with cellulose which had been dried at
105°C. Using x-ray study, nitrogen determination, and water sorption, he
determined that the carbamate esters are actually formed and concluded
that the isocyanate reacts first with the available hydroxyl units, then
penetrates into the.crystalline structure of cellulose to react with other
hydroxyl units.
Reactions with Isocyanates react with hydrogen atoms attached to
Hydrogen attached nitrogen in such compounds as amines, amides, ureas, and
To Nitrogen carbamates, but the reaction rates are affected by
nuclear substituents and steric hindrance.
Amines (XII) will react with isocyanates as shown in reaction 7:
R NCO + R'NH2 -*• R NHCONItR1 [7]
I XII XIII
The product is a substituted urea (XIII).
Aliphatic amines are generally more reactive than aromatic amines
which are more reactive than pyrrole, but these reaction rates are especially
affected by steric hindrance caused by ortho-substitution of the phenyl
ring. The reaction of isocyanates which contain N-H bonds is governed
primarily by how basic or nucleophilic the N-ll bond is; isocyanate reactivity
decreases approximately in the order (1)
4(-N02) > 3(-N02) > 3(-OCH3) > H > 4(-CH3) > 4(-OCH3)
whc»-ds amine activity tends to increase in the same order.
Amides (XV) will react with isocyanates as shown in reaction 8:
0 99
RNCO + R-C-N1L -*• R'-C-N-fc-NR [8]
^ H II
I XV XVI
The reaction product is a substituted biuret (XVI).
Urea (XVII) being a diamide will react with isocyanates as shown in
reaction 9:
47
-------
RNCO + H2NCONH2 •> RNHCO NHCONH2 [9]
I XVII XVIII
Again, the reaction product is a substituted biuret (XVIII).
Carbamates (XIX) will react with isocyanates as shown in reaction 10:
RNCO + R'NHCOOR" •> RNHCO-N-COOR"
R'
[10]
I
XIX
XX
The reaction product is an allophanate (XX) which decomposes at elevated
temperatures to produce two isocyanates (XXI, XXII) and an alcohol (XXIII)
as shown in reaction 11:
RNHCO-N-COOR"
t'
XX
RNCO + R'NCO + R"0'l
[11]
XXI
XXII XXIII
This reaction is reversible, however, and upon cooling the allophanate may
again be formed.
Kinetics and The electronic structure of isocyanates is approximated
Mechanisms of in reaction 12, with the possible resonant structures
Isocyanate Reaction shown as:
R._N=C=0: •*-* R-N-C=0: «-* R-N=C-0: [12]
Isocyanate reactivity is affected by the composition of the aryl or alkyl
group, R.
The hydroxyl groups of alcohol may catalyze the reaction between alcohols
and isocyanates according to Arnold et. al. (1), reaction 13. (Ar=aryl)
Ar-NCO + ROH
Ar-NCO
ROH
k3
ROH
Ar-NHCOOR + ROH
[13]
It is clearly seen that alcohol with its slightly basic oxygen can act
as its own basic catalyst, while phenols, being more acidic or less basic,
do not catalyze themselves as well, and therefore, need the aid of a
basic catalyst in order to have reasonably fast reaction times. In addition,
phenols have the resonance form shown in reaction 14, which tends to lessen
their basicity even more. The result is a reaction rate about equal to
the very sterica'ly hindered t-butyl alcohol.
48
-------
-OH <-* !<(}>= 0-H [14]
The hydrogen attached to the nitrogen of amines will react with
isocyanates to form a substituted" urea. In fact, methyl isocyanate reacts
nearly 200 times faster with an amine group than it does with hydroxyl
groups. In a mixture of alcohol and water, the rmine formed would tend to
catalyze the reaction of the isocyanatg: with both the hydroxyl groups of water
and of the alcohol, but the amine would also react with the isocyanate to
form a substituted urea.
Process: A schematic diagram of the process is shown in Figure III. B. 1
Baled straw is milled to reduce the particle size, and is dried to reduce
the water content. The fines are removed by screening and the isocyanate
resin is applied by air spraying. The mixture is pressed into a solid
board with a heated-platen hydraulic press. The boards are then finished
and stored. If the straw contains 15% moisture, and 5% resin is applied,
120 pounds of baled straw will be needed to produce 100 pounds of finished
board with 5 pounds of trim. Theoretically the trim could be passed
through the process again but no allowances were made in the diagram for
this operation.
A discussion of some of the variables involved in each step of the
process is given below.
Straw Theroetically, any straw could be used in this process to form
Type a straw purticleboard, but differences in composition and
structure may affect both the physical properties and appearance of the
board. The only differences in physical properties that have been
measured thus far show that the physical properties of cascade fescue
and hard fescue are significantly lower than the physical properties of
annual ryegrass when the three straws are processed in the same way
(Figure III. B. 2.). Differences in appearance are also noticeable
between such straws as annual ryegrass, cascade fescue, hard fescue,
and highlight fescue. Both the size (width) of the straw stalk and the
color of the particles contribute to these differences.
Differences in wax content might also contribute to differences
in physical properties, since it has hp*»n shown that the removal of
wax from the surface of the straw particle improves the strength of
straw particleboard (see Figure III. B. 2.).
Particle The straw particle size can be reduced by passing the straw
Size through a mill; the average particle size being determined
by the size of the holes in the screen.
Straw particleboard strength is directly affected by particle size
because small particles, having more surface area, tend to pack more tightly
and collect more resin, while the tensile strength of longer particles
is also a factor.
49
-------
Differences in the handling characteristics of straw particles have
also been noticed; short particles flow more easily than longer particles,
but produce a board of lower strength.
Moisture Moisture content is an important variable for two reasons;
Content the reaction of water with the isocyanate resin, and the
vaporization of the water during the pressing cycle.
Although no direct measurements have been made, there is no
apparent detrimental effect on the board physical properties by the
presence of a small amount of water in the straw, that is, strong boards can
be produced whether the water is removed prior to application of the
resin or during the pressing operation itself, however, the temperature
profile of the board in the press will be different i: the two cases.
In addition, it is presumed that any water in the straw would react with
the resin over a period of time if the resin-straw mixture were being
stored prior to utilization.
Any gas that is produced in the board during the pressing operation
must be allowed to escape prior to releasing the pressure or delamination
(blows) will occur.
Resin Three variables involving the r^sin may affect the board
physical properties; resin type, resin concentration, and resin application
method.
A variety of isocyanate resins are available industrially including
4,4'-diphenyl methane diisocyanate, polymethylene polyphenylisocyanate,
tolylene 2,4-diisocyanate, hexamethylene diisocyanate, and m-xylylene
diisocyanate. The reaction rates of these compounds with cellulose and
with water are unknown, however, straw particlebcards have been made
in the laboratory with tolylene 2,4-diisocyanate (with dibutyltin diacetate
catalyst), 4,4'-diphenylmethane diisocyanate, and polymethylene poly-
phenylisocyanate .
Resin concentration should have a direct effect on the board physical
properties, unless the breaking strength is determined by other factors
such as the internal cohesion of the straw particle. Although the effect
of changes in resin concentration on board physical properties has not
been completely evaluated, preliminary tests have shown that the board
strength increases as the resin concentration increases.
The technique of resin application will affect the distribution of
the resin on the straw particles. Lehmann (12) hai shown that the
distribution of resin is the most important factor in the strength and
stability of wood particle boards. He has also shown that fine atomization
of the resin and a suitable period of application were ti
-------
solvent can also be used to reduce the resin viscosity and improve the
atomization, but boards produced in this manner do not have the strength
of those made with the undiluted resin.
A uniform application of resin could also be attained by soaking
the straw in a solvent solution of the resin.
Pressing The straw-resin mixture forms a solid board when it is
subjected to heat and pressure for an adequate length of time. Variables
in the pressing operation include pressing time, pressing temperature,
pressure, and speed of closing. Although the speed of closing can be
adjusted to change the ratio of the modulus of rupture to the internal
bond in a wood particleboard process, no evaluation of this variable
has been made in this study.
Pressing time is measured from the time the press reaches maximum
pressure, or from the time the press is closed if stops are used.
The time must be long enough for the center of the board to heat up and
complete the reaction, but should not be too long because degradation
may occur. Preliminary studies have shown that board strength increases
with an increase in pressing time up to a point, and then decreases.
The optimum pressing time is determined by the pressing temperature.
The effect of pressing temperature on t.h? physical properties of
the straw particleboard has not been determined, but will affect the
temperature profile within the board and the degradation rate of board
components. The temperature must be high enough to allow the reaction
to be completed, but should not be too high because the straw will
undergo thermal decomposition. Preliminary tests have shown that the
range of allowable temperatures is 250-400°F, with 325-3SO°F being most
desirable.
The pressure exerted on the straw particles will determine the thickness
and density of the resulting board unless stops are used. An increase
in pressure results in a decrease in thickness and an increase in
density. When stops are used the pressure is no longer a variable, as
long as the press can be closed, and the density will be determined by
the amount of straw being used, and the thickness will be determined by
the stops. However, a higher density board will require a higher
pressure for closure, and the effects of higher pressure on physical
properties can be measured in terms of the effects of higher density.
In general, the strength of a straw particlebourd increases as the
density increases regardless of whether the thickness or the weight of
the board is held constant.
Finishing The finishing operations that are required will depend on
the techniques being used in the pressing operation. If the boards
are pressed in a mold, the edges will be firm and no trimming will be
required; however, if the boards are pressed with unrestrained edges,
they will be soft and will need to be trimmed. In addition, it may
be desirable to provide the board with a paint, lacquer, or vinyl finish.
51
-------
Experimental Results; Three sizes of straw particleboard samples have
been prepared for evaluation, a laboratory test sample measuring 4 1/2 inches
by 4 1/2 inches, a standard test sample measuring 12 inches by 12 inches, and
a commerical test sample measuring about 4 feet by 8 feet. All of these
samples were prepared from baled straw that had been stored in an open
shed for at least six months. The results of these tests are listed below.
Laboratory These samples were prepared using a manually operated,
Test Samples heated-platen (5 inch by 8 inch), hydraulic press and a
2-piece mold designed to produce a 4 1/2" x 4 1/2" x 3/8" board. Although
these samples were too small to allow the use of ASTM standard testing
procedures for the determination of physical properties, non-standard
tests were used to show differences rather than absolute values.
The Modulus of_ Rupture (MOR) is influenced by the board density
as shown in Figure III. B. 3. These samples were prepared at 350°C
using 3% isocyanate resin. This straw was milled on a hammermill with
1/4" screen and was dried prior to the resin application. The optimum
pressing time for these conditions is five minutes. The MOR increases
with increasing density.
Figure III. B. 4. shows the effect of pressing time on MOR for samples
prepared at 340°C using 3% isocyanate resin. This straw was milled on
an Abbe mill with 3/16" screen and was dried prior to the application
of the resin. The optimum pressing time for these conditions is two
minutes or less, and again the MOR was higher for the boards produced with
higher density.
Figure III. B. 5. shows the effect of resin concentration on MOR
for samples prepared at 300°F. This straw was milled on a hammermill with
a 1/4 inch screen and was not dried prior to application of the resin. In
addition, a small amount of acetone was used in the resin to lower its
viscosity and the straw-resin mixture was stored in a plastic sack
for about 24 hours prior to pressing. The optimum pressing time for
these conditions is four minutes, except for a resin concentration of
1.25%, then it is five minutes or longer. At two minutes pressing time
the optimum resin concentration is 2.0%, while for pressing times of
three, four, and five minutes the optimum resin concentration is 1.5%.
The thermal conductivity of straw particleboard was determined and
compared to samples of wood particleboard, asbestos, and air.
Since heat transfer through a_jnaterialgby conduction is governed
by the Fourier equation, -r- = kA -r— where -jr- is the rate of heat flow,
A is the area of contact perpendicular to neat flow, ^- is the temperature
gradient through the material and k is the thermal conductivity constant
for the material, the thermal conductivity constant for a test material
(k) can be determined byapplying heat to one side of a stack which includes
materials with known k's, and measuring the temperature gradient through
the stack:
52
-------
d
dt s Vt &
kt
Experimentally, a stack containing plates of aluminum, straw
particleboard, and copper was placed in a heated platen hydraulic press.
The lower platen was heated to 230°F and the top platen was held at room
temperature. Pressure was applied to the stack to insure good contact
between the layers in the stack. After 20 minutes the temperature profile
through the stack was measured with iron-constatan thermocouples. In
addition to straw particleboard, samples of particleboards made from
Sander dust and municipal refuse were evaluated and also samples of commercial
wood particleboard, asbestos, balsa wood, air, and loose straw. The
results of these tests are listed in Table III. B. 1.
The relationship between density and thermal conductivity constant
is shown in Figure III. B. 6. Although no clear relationship is evident,
the thermal conductivity appears to increase slightly with increase in
density. A more significant factor appears to oe the classification of
the straw. At approximately the same density, the thermal conductivity
increases as the particle size increases, with the exception of the fines.
However, the boards with the lowest conductivities were prepared from
heterogeneous straw with the fines removed.
Although straw particleboard seems to be a better thermal insulator
than most of the other materials measured, a comparison with insulating
materials has not been computed.
The water absorption properties of several samples of straw particle-
board were measured to determine if changes in processing variables
affected the p.ter absorption properties. Since this test was not
conducted according to the ASTM standard, only the differences in
weight and length measurements were observed. The boards used in this
test were 4 1/2 inches square and about 3/8 inch thick. Weight and length
measurements were made prior to and after soaking under 1 inch of water
for 24 hours.
The water absorption properties of straw particleboards appear to be
affected by the type of resin used, the resin concentration, the moisture
content of the straw prior to pressing, and the density of the board, but
not by variations in resin application procedures.
Standard These samples were prepared using an automatic hydraulic
Test Samples press with steam heated platens (24 inch by 24 inch). The
straw mat was hand formed between two stainless steel caul plates, 12
inches by 12 inches, and placed on the lower platen. The press closing
time was about 30 seconds. The first series of samples were prepared by
53
-------
applying constant pressure; variations in pressure resulted in variations
in the density and thickness of the boards produced. The second series
of samples were prepared using stops to achieve a thickness of 3/8 inch.
Variations in density were produced by variations in the quantity of
straw used in the mat. The boards were trimmed to 11 1/2 inches by 11
1/2 inches, providing an adequate sample for physical testing using ASTM
procedure D-1037-64. The physical properties of these test samples are
listed in Table III. B. 2.
The density of the boards is determined primarily by the level of
pressure applied, when stops are not used. The relationship between
pressure and density is shown in Figure III. B. 7. When a constant pressure
of over 1000 p.s.i. was applied for over one minute, "blows" appeared in
the board. Although an alternative technique of allowing the straw mat
to heat up for two minutes at 200 p.s.i. prior to application of the
higher pressure prevented the "blow" formation, this technique also
affected the physical properties of the boards including the density.
Board density is also affected by the pressing time. The effect of
pressing tine on board density is also shown in Figure III. B. 7.
Time apparently has a greater effect on board density at high pressure
(1000 p.s.i.) than at low pressures (200 p.s.i.).
The Modulus of_ Rupture is affected by the removal of wax from the
straw. Figure III. B. 2. shows the effect of wax removal on MOR for
three kinds of straw. The removal of wax from the straw results in a
significant increase in MOR, but loss in water swell properties.
The Modulus of Elasticity (MOE) is influenced by board density as
shown in Figure III. B. 8.These samples were prepared with 5% isocyanate resin.
An increase in density results in an increase in MOE. Variations in
Figure III. B. 8. may be caused by variations in average particle length.
The MOE is also affected by the removal of wax from the straw.
Figure III. B. 2. shows the effect of wax removal on MOE for three kinds
of straw. The removal of wax from the straw results in a significant
increase in MOE, but this effect is not as great as the effect on MOR.
The internal bond values listed in Table III. B. 2. are not
indicative of the actual strength of the boards since the separation during
testing occured at the metal surface and not within the board; therefore,
it is not possible to show the effects of changes in board density or
thickness on the I.E.
Figure III. B. 2. shows the effect of wax removal on the I.E.
for three kinds of straw. The removal of the wax results in a significant
increase in the I.E.
54
-------
The water absorption properties of several different materials,
pressed under varying conditions are shovm in Table III. i. 3. Reproducibility
of results, holding all parameters constant, is indicated by samples 2
and 9. Variation of resin type produced the results shown in samples 1,
11, and 15.
As one can see from samples 5, 6, and 7, or 9 and 11, resin concentration
has small influence on water absorption properties. Density also has only
a. small influence as shown in samples 1 and 8.
Samples 18 and 19 were cut from a single sheet of commercial wood
particleboard for use as a comparison with laboratory products. Eight
percent PAPI on straw gives about the same water absorption properties
as the 6-8% resin used in the wood counterpart as can be seen by comparing
samples 18 and 19 with samples 2 and 9.
The samples made from paper were inferior, possibly because of the
lack of wax "sizing". Sizing is added to wood particleboard, but because
of the natural wax in straw there is no need to add sizing to straw
particleboard.
In general one can summarize by noting that increased density and
increased resin concentration reduce the swell caused by water absorption
in straw particleboard. The polyisocyanate resin, Mondur MRS, appears to
give slightly better moisture stability characteristics than the other
resins tested. Paper might be used as a fiber source if wax is added
to decrease the water absorption.
Commercial Two commercial samples were prepared in a 5 foot by 9 foot
Test Samples multi-opening press to evaluate the engineering factors
involved in industrial production of full sized sheets (4 foot by 8 foot).
The straw was milled in a hammermill with screen openings larger than
1/2 inch diameter, and was dried in a tray drier at 65°C for 24 hours. The
isocyanate resin was applied at 5% to 1600 gram batches of straw, and
the mixture was stored in plastic bags for 24 hours prior to pressing.
Approximately 35 pounds of treated straw were used in each board.
The straw mat was hand formed on an aluminum caul plate and the plate
was lifted onto a conveyor belt for feeding into the press. Paper was
used on the top and bottom of the mat to prevent sticking to the platens.
The platens were heated to about 325°F and the pressing time was about
5 minutes. A constant pressure of over 1000 p.s.i. was applied.
When the pressure was released, the boards delaminated severely,
although the two layers appeared to have good cohesion. Wide variations
in thickness were observed; this resulted from the hand forming operation.
The straw does not flow readily and is difficult to form into a uniform
mat. The paper that was used stuck to the straw particleboard on both
sides hut most of it could by removed by soaking it with water and scraping
55
-------
it with a spatula. The soft edges were trimmed and the resulting board
showed no major defects except for the delamination. No physical properties
were measured.
In order to produce full sized sheets for physical testing, a
mechanical mat forming device should be used, and if resin sticking is a
factor, release paper should be employed. In addition, the pressing
conditions should be adjusted to prevent delamination.
56
-------
References
1. Arnold, R. G., J. A. Nelson and J. J. Verbank, "Recent Advances in
Isocyanate Chemistry", Chemical Reviews, 57, 47-76 (1957).
2. Bayer, 0., "Das Di-isocyanate-Polyadditionsuerfahren (Polyurethane)",
Angewandte Cheinie, A59_, 257-288 (1947).
3. Chadwick, D. H., and E. E. Hardy, Kirk-Othmer Encyclopedia of Chemical
Technology, Vol. 12, pp. 45-64, John Wiley and Sons, Inc., 1967.
4. "Citric Acid Crosslinks Cellulose", Chemical and Engineering News,
40(49), 42 (1962).
5. Eckert, P., and P. Herr, "Formation of Bridged Compounds in Cellulose
Fibers with Diisocyanates", Kuntseide und Zellwolle, 25, 204-210
(1947).
6. Ellzey, S. E., and C. H. Meek, "Reaction of Aryl Isocyanates with Cotton
Cellulose. I. Variables in Reaction Using Phenyl Isocyanate",
Textile Research Journal, 32_, 1023-1029 (1962)
7. Ellzey, S. E. Jr., C. P. Wade, and C. H. Mack, "Reactions of Aryl
Isocyanates with Cotton Cellulose. II.", Textile Research
Journal. 32_, 1029-1033 (1962).
8. Hearon, W. M., G. D. Hiatt, and C. R- Fordyce, "Carbamates of Cellulose
and Triacetate; Preparation", Journal of The Aoerican Chemical
Society, 65_, 829-833 (1943).
9. Hearon, W. M., G. D. Hiatt, and C. R. Fordyce, "Carbamates of Cellulose
Acetate. II. Stability Towards Hydrolysis", Journal of The
American Chemical Society, 6S_, 833-836 (1943).
10. Hearon, W. M. and J. L. Lobsitz, "Aryl Carbamates and Cellulose
Acetates", Journal of The American Chemical Society, 70,
296-297 (1948).
11. Hobart, S. R., H. H. McGregor, and C. H. Mack, "Reaction of Aryl
Isocyanates with Cotton Cellulose. IV. Reactions Via Phenyl
N-Aryl Carbamates", Textile Research Journal, 38, 824-830
(1968).
12. Lehmann, W. F., "Improved Particleboard Through Better Resin Efficiency",
Forest Products Journal, 15, 155-161 (1965)
13. Sauniers, J. H., and R. J. Slocomb, "The Chemistry of Organic
Isocyanate", Chemical Reviews, 43, 203-218 (1948)
57
-------
14. Schneebli, "Etude de 1'addition de 1'isocyanate de Phenyle sur les
Fonztions Alcool de la Cellulose", Acadamie Des Science,
Comptes Rendus, 254, 738-740 (1952).
15. Volozhin, A. I., 0. P. Kozmina, and S. N. Danilov, "Synthesis and
Properties of N-substituted Carbamic Esters of Cellulose",
Zh. Prikl. Khim, 37(12), 2761-2763 (1964); Institute of Paper
ChTmists, Abstract Bulletin, 36:183 (1965).
58
-------
en
to
i
I
*
s
Straw
Ra 1 gs
Wire
Figure III. B. 1. Schematic Diagram for Straw Particleboard Formation.
-------
7 -I
140
120
100
to
JO
60
•o
o
CO
20 -
Unextracted
Extracted
Unextracted Extracted
Unextracted
Extracted
Figure III. B. 2. Effect of Wax Removal on Straw Particleboard Physical Properties.
-------
I
7 '
6 '
5 -
4 -
3 •
2 -
1 '
A A
4-
30 40 50
Density (Lbs./Cu.Ft.)
60
Figure III. B. 3. Increased Board Strength Brought About by Increased
Density. Point A Indicates Increase of Strength
Because of Longer Fibers.
61
-------
5000
4000
i-i
*j
I
•o
O
3000
2000
1000
2 3 4
Time (Min.)
Figure III. B. 4. Effect of Pressing Time on Modulus of Rupture.
62
-------
cr
(A
in
3
o
o
o
o
(H
I
o
IA
O
Resin (%)
Figure III. B. 5. Increased Board Strength Caused by Increased Resin
Concentration.
63
-------
Ib
o
us
s
C
3
•H
•ri
O
U
<«
6
4)
90
80
70
60
50
O
20
O
o
30
Heterogeneous
Mixture
Hetrogeneous
Mixture
Fines Removed
40
SO
Density (Lbs./Cu. Ft.)
Figure III. B. 6. Relationship Between Density and Thermal Conductivity.
64
-------
u.
in
3
•H
V)
64 '
62
60 '
58 •
56
54
52
50 •
o 48
46 '
44 -
42
40
38 '
36
5 Min.
12 3456 789
Pressure (100 Lbs./Sq. In.)
Figure III. B. 7. The Relationship Between Pressure and Density.
10
65
-------
600
500 '
x 400
•rl
U
•H
in
(8
fH
UJ
<4H
O
3
I
300
200
100
20 30
40
50
60
Density
Figure III. B. 8. Showing the Influence of Density on the Modulus of
Elasticity.
66
-------
Table III. B. 1. Thermal Conductivity oi- Straw Particleboard
and Other Substances
Sample Thickness, Density, k
in. Ib/cu.ft. BTV/hr.(ft2)(°F/ft.)
Straw particleboard, heterogeneous mixture
1 0.247 30.0 0.76
2 0.255 27.5 0.84
3 0.231 28.2 0.76
4 0.238 25.4 0.95
5 0.232 23.8 0.79
6 0.243 20.8 0.73
7 0.25D 30.8 0.78
8 0.267 31.7 0.80
Straw particleboard, classified
Fines
9 0.237 30.4 0.73
10 0.245 45.0 0.85
11 0.298 49.6 1.08
12 0.215 34.6 0.83
Medium length
13 0.233 30.4 0.59
Medium/coarse length
14 0.229 30.9 0.66
Coarse
15 0.228 30.4 0.71
Heterogeneous, but with fines removed
16 0.244 40.0 0.61
17 0.224 33.0 0.52
Loose straw
18 0.360 3.7 0.78
Balsa wood
19 0.225 0.67
Commercial wood particleboard
20 0.367 1.12
Asbestos
21 0.250 1.20
Sander dust
22 0.216 1.57
Municipal refuse
23 0.294 1.72
Air
24 0.360 1.01
67
-------
Table III. B. 2. Physical Properties of Straw Particleboard
CO
2
3
4
S
6
fj
i
8
9
Sasiple
No.
1 (w)
'(*)
(w)
(w)
(w)
(w)
(w)
(w)
(w)
10 (w)
11 (w)
12 (w)
13 (w)
14 (w)
15 (w)
16 (w)
17 (w)
18 (w)
19 (u)
20 (w)
21 (u)
22 (w)
23 (u)
Straw
Type
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
AR
HF
HF
CF
CF
Temp.,
°F
V^*i^^H^^^^^M
344
343
344
345
347
346
344
344
345
349
344
340
358
346
350
354
354
325
525
325
325
325
325
Press . ,
psi
216
216
216
540
540
540
1080
200/1080
200/1080
200/2160
200/2160
216
216
216
216
216
216
stops
stops
stops
stops
stops
stops
Time,
min.
1
3
5
1
3
5
1
2/1
2/3
2/1
2/3
1
3
5
1
3
5
4
4
4
4
4
4
Ave. Density,
Ib/ft *
37.4
37.6
37.8
48.1
54.9
55.8
57.6
55.0
58.2
61.3
63.8
37.2
39
40
36
37
.7
.7
.4
.4
41.0
44
44
44
43.8
44.7
36.4
Ave. Thickness,
in.
0.220 2190
0.212 2369
0.208 2276
0.173 4520
0.141 5680
0.148 6892
0.137 6740
0.148 4477
0.137 4655
0.132 5375
0.133 2696
0.149 2621
0.135 3642
0.136 2990
0.069 2603
0.070 3588
0.066 5818
0.333 4318
0.334 3873
0.335 2408
0.336 31S6
0.337 1662
0.331
MOE,
1000 psi
308
341
338
545
672
780
772
580
669
718
746
367
341
443
364
434
607
626 t
565
498
438
450
258
IB,'
psi
61
82
84
90
130
110
88
65
94
66
94
68
98
80
, 103
61
116
6S
80
32
f
(s)
(s)
(s)
(s)
(s)
(s)
(s)
(s)
(s)
(s)
(s)
1 (w) means extracted, (u) means unextracted
2 (AR) means annual ryegrass, (HF) means hard fescue, (CF) means cascade fescue
3 (s) means surface failure
-------
Table III. B. 3. Changes in Weight and Linear Dimensions of Boards Made From
Various Materials When Soaked in Water for 24 Hours.
Substance
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
13
19
Straw
Straw
Paper
Sanderdust
Sanderdust
Sanderdust
Straw
Straw
Straw
Paper
Straw
Straw
Straw
Straw
Straw
Wood particle
Wood particle
Treatment
Dried 110°C/15 hr.
Field run (9% H2<3)
Ground § dried
Abbe treated
110°/15 hr.
Field run (9% H20)
Ground § dried
Air dry after spray
Air dry 65°C
HO0/ 15 hr.
Air dry 65 °C
Commercial
Conunercial
Resin
Type
PAP I
PAP I
PAP I
PAP I
PAP I
FAPI
PAPI
PAP I
PAPI
PAPI
P-F
PAPI
MRS
MRS
MRS
Wt. %
5.5
8
8
3
4
5
5
5
8
8
5
10
5
5
5
Density
Dry (g/cc)
0.81
0.98
0.66
C.65
0.6S
0.71
0.82
0.66
1.01
0.66
0.99
0.94
0.62
0.60
0.69
0.63
0.64
Dimensional Change
Length % Weight
0.866
0.347
0.435
2.
2.
2.
.34
.54
.34
0.868
0.866
0.347
0.435
1.04
0.433
0.86
0.605
0.605
0.343
0.343
58
28
46
46
42
36
49
56
30
33
67
22
37
25
38
43
34
-------
Nitrogen and Phosphorus Enrichment
The use of solid wastes as soil conditioners and fertilizers is hindered by
their low concentration of plant nutrients, especially nitrogen, phosphorus,
and potassium. Since the soil is an ideal location for the disposal of large
quantities of solid wastes, it seems reasonable to consider enriching
solid wastes with plant nutrients in order to make land disposal more
attractive. For wastes containing large amounts of cellulose this can be
done chemically by preparing cellulose derivatives that contain nitrogen,
phosphorus, and potassium. The water-holding capacity of these organic •
materials, their insolubility in water, and their slow rate of degradation
would be additional desirable characteristics. Since nitrogen and
phosphorus are the two main plant nutrients required, this report will
be limited to consideration of these. Potassium can be added to some
cellulose derivatives which have ion exchange properties.
Chemistry: Many cellulose derivatives can be produced which contain
nitrogen and/or phosphorus. A more extensive discussion of the chemistry
involved in their formation entitled "Cellulose Compounds Containing
Nitrogen" (2), can be found in a report prepared by J. F. Barbour; however,
the present report will be limited primarily to consideration of the
cellulose-urea and cellulose-phosphoric acid reactions.
Nitrogen Cellulose derivatives containing nitrogen can be prepared
Enrichment by reacting cellulose with urea, ammonia, or nitric acid.
In each case the concentration of nitrogen in the product will depend on
the extent of the reaction.
Urea reacts with cellulose under the influence of heat. Extensive
research on the cellulose-urea reaction has been conducted by the textile
industry for the purpose of improving the crease resistance of cotton
fabrics. When a mixture of urea (I), cellulose and a catalyst are heated,
the product contains chemically fixed (water insoluble) nitrogen, presumably
in the form of cellulose carbamate (II), as shown in reaction 1:
CuCl,
Cell-OH + NH2CONH2 -*• ^ Cell-OCONH2 + NHj [1]
I II
When this reaction is conducted in a closed chamber, the nitrogen content
of the product is very low, indicating that the reaction is inhibited.
Nuessle (8) concludes that the urea decomposes into cyanic acid (HNCO)
and ammonia (NH_) and that the ammonia must be removed in order for the
reaction to proceed; however at low temperatures cyanic acid (III) can
trimerize to form cyanuric acid (IV), as shown in reaction 2:
70
-------
3 Cell - OH + |
H
,^-N,
0 = C "C = 0
3 HNCO - »- j |
H - N. N - H
^C-^ [2]
0
III IV
which can react with cpllulo e to form the cyanic acid ester (V) as
shown in reaction 3:
0
3 Cell - 0 - 5 - NH, [3]
IV V
Ammonia, under heat and pressure will react with cellulose to form
"amino cellulose" as shown in reaction 4:
Cell-OH + NH3 -" Cell-NH2 + H20 [4]
VI
"Amino" cellulose has been studied in relation to its fertilizing
properties by Davis, et.al, (4), who describes the conversion of ammoniated
peat to usable nitrates in the soil. They indicate that the amount of
nitrogen available .s a function of the temperature at which the cellulose-
ammonia reaction takes place and that some of the nitrogeneous materials
formed are soluble in water and some are not.
When cellulose is soaked in annydrous liquid ammonia, the fibers
are swollen and remain swollen when the ammonia is removed by heating at
105°C. X-ray diffraction studies (3) have shown that the airaronia is not
bound to the cellulose at regular intervals and presumably amino cellulose
is not formed.
Anderson (1) reports that mineral acids, such as 8.25% sulfuric acid,
can be used to hydrolyze the hemi-cellulose before reaction with ammonia.
When hydrolyzed cellulose was treated with ammonia at a temperature
slightly above room temperature, the product contained 7.4% nitrogen
which was 84% water soluble. When the hydrolyzed cellulose was treated
with ammonia at 249°C the product contained 9.5% nitrogen which was 17.6%
water soluble. When the reaction temperature was raised to 300°C, the
product contained 4.6% nitrogen, none of which is water soluble.
The product of the low temperature reaction was nearly as good as ammonium
71
-------
sulfate when used as a fertilirer, but the other products had a lesser
effect on plant growth.
Nitric acid will react with cellulose to produce nitrate (VII) as
shown in reaction 5:
Cell-OH + HNO, -»• Cell-ONO, + H.O [5]
O £ i
H,SO.
2 4 VII
Complete nitration of the cellulose molecule results in cellulose
trinitrate. Cellulose nitration can be achieved, with a mixture of nitric
and sulfuric acids, nitric and phosphoric acids, nitric acid and acetic
anhydride, or nitric acid and methylene chloride. When sulfuric acid is
used, the process is very rapid with most of the reaction occurring in
the first few minutes because the nitric acid readily penetrates into the
cellulose micelle.
Cellulose nitrates can be modified to produce carboxy-cellulose
nitrates, cellulose nitrosyl sulfates, and cellulose nitroethyl ethers.
Cellulose nitrates are extremely flammable, and when confined, are
considered explosives. They are used in the manufacture of smokeless
powder and rocket propellants as well as in plastics, films, and lacquers.
Phosphorus When cellulose is treated with phosphoric acid, the ester
Enrichment cellulose phosphate (VIII), is produced as shown in
reaction 6:
Cell-OH + H3P04 -»• Cell OPO(OH)2 + H20 [6]
VIII
Nikitin (7) claims that two reaction products are possible with
cellulose and phosphoric acid, one being an addition product, that is
easily hydrolyze-J by water and the other being the ester which is unaffected
by water, consequently, phosphorus fixation can be determined by measuring
the phosphorus concentration of the reaction product after washing with
water.
Cellulose derivatives containing phosphorus can also be prepared by
reacting cellulose with ammonium phosphate, phosphorus tri- and oxy-
chlorides, monophenyl phosphate, phosphorus pentoxide, and alkali-metal
salts of phosphoric acids.
Gallagher (5) reports that sodium phosphate acts as a crosslinking
agent forming dicellulose phosphate (XIX) as shown in reaction 7:
72
-------
2 Cell-OH + NaH,PO. -»• Cell-OPO-Cell [7]
^ 4 ONa
XIX
The addition of phosphorus to cotton cloth has been studied extensively
by the textile industry in order to achieve a flameproofing property.
An extensive summary of the chemistry and uses cf fire retardants is
given by Lyons (6) .
Nitrogen and When cellulose is reacted with a mixture of urea and
Phosphorus phosphoric acid, the product is cellulose ambonium phosphate
Enrichment (XX) or cellulose amide phosphate (XXI), depending on the
reaction temperature, as shown in reaction 8:
under
Cell-OH + NH2CONH2 +
over
Since cellulose phosphate has ion exchange properties, other cations
can be added to the compound, such as potassium, iron, or calcium.
Process : A schematic diagram of the process is given in Figure III.
C. 1.
The solid waste containing cellulose is milled to reduce the particle
size and then soaked in a water solution of the appropriate reagents.
If only nitrogen enrichment is desired, the solution will contain urea
and a catalyst, probably cupric chloride. If both nitrogen and phosphorus
enrichment are dasired the solution will contain urea and phosphoric
acid. After soaking, the excess solution is removed by filtration. The
wet mixture is dried and then heated to the reaction temperature.
Following the reaction, the product is washed with water to remove any
water soluble product or unused reactants. The product is then dried
and stored. A discussion of some of the variables in the process is
given below.
Solid Any solid waste containing cellulose could theoretically
Waste be used in the process to produce a nitrogen and/or
phosphorus enriched product with fertilizing properties; however, the
nature of the impurities will affect the efficiency of the reaction, for
example the fillers, sizing, wax, and ink that are added to paper used
in magazines may reduce the availability of cellulose hydroxyl units for
reaction.
73
-------
Milling Of Solid wastes can be milled to reduce the particle size for
The Haste easier handling and to increase the available surface area
for chemical reactions. Milling can be accomplished by use of a number of
pieces of equipment such as hammermills, shredders, raspers, and hydro-
pulpers.
Soaking In_ The soaking step is designed to produce a uniform mixture
The Reagent of the reactants, and although water is the common solvent,
Solution other solvents might be used. Although the time required
for complete mixing is not great, chemical reactions during this step may
affect the concentration of reagents in the cellulose after pressing.
Since the solvent mixture can be recycled, the amount of chemicals and
solvent added each time will equal the amount of chemicals and solvent
entrained in the cellulose.
This process could be a batch or continuous operation.
If uniform mixing of the reactants with the cellulose is not
required, such as would be the case if the reaction were vapor phase,
then soaking and filtering would not be required.
Filtering Tp_ The excess solution can be removed from the cellulose by
Remove Excess filtering, filter pressing, or by centrifuging, depending
Reagents on which method provides the best wet/dry ratio. When this
ratio is" high, more heat will be required to remove the solvent. The
reactant concentration in the solvent will have to be adjusted in order
to attain the appropriate concentration of nitrogen and phosphorus in the
cellulose.
Drying To Tne purpose of'this step is to remove the excess solvent
Remove The carried along in the cellulose. Although this step could
Solvent be included in the first part of the heating step, it may
be desirable to recycle the solvent or to collect a component of the
reaction gases. Pre-drying will allow a better measure of the actual
reaction time, but reactions may also occur at the drying temperature.
Drying, if it is used, can be accomplished in a variety of ways, such
as tray, rotary drum, vacuum, and radiant heat drying.
Heating Tp_ This step provides the temperature for completion of
Promote The reaction. The reaction temperature and reaction time
Reaction will probably both affect the speed and extent of the reaction
These factors will also have ar. effect on the degradation rate of the
organic components of the waste, which may influence the physical
and chemical properties of the product.
Washing Tp_ When a water-insoluble product is desirable, washing
Remove Unre icted will be required, after the reaction is completed,
Materials to remove unused reagents and water soluble reaction
products. These compounds can be recovered for reuse by drying, or the
74
-------
water solution could be reused in the soaking operation. In actual
practice, it may be beneficial to leave some water soluble plant
nutrients in the final product to provide an immediate stimulus to the
plant growth. The fixed nutrients would then become available as the
enriched cellulose slowly degraded.
Experimental Results; In the laboratory, samples of newspaper and
straw have been treated with ammonia, nitric acid, urea, and phosphoric
acid to give products with varying concentrations of nitrogen and.
phosphorus. Several different techniques were used for mixing and
heating the reactants. Nitrogen and phosphorus concentrations were
measured before and after water washing to detemdne the levels of
fixed nutrients in the product. Selected samples of these products
were then tested in a greenhouse soil test to determine if they possessed
fertilizing properties comparable to commercial fertilizers. The long
range or "slow release" fertilizing properties have not been evaluated
as yet.
Nitrogen Urea, was reacted with cellulose in a series of experiments
Enrichment to determine the affects of changes in reaction variables
on the degree of nitrogen fixation in the cellulose of newspaper.
The effect of reaction time on nitrogen fixation is shown in
Figure III. C. 2. Shredded paper was soaked in a 40% solution of urea
for two hours and the excess solution was removed by filtration to give
a wet/dry ratio of 4.5. The wet paper was dried for 16 hours at 110°C
and then divided into eight parts ivhich were reacted at 150°C for varying
times up to 17 hours. The level of nitrogen fixation increases as the
reaction time increases, however, the maximum level of fixation was not
determined initially. The maximum fixation possible under these conditions
was later determined (Curve B) using a 50% urea solution ard a 4.4
wet/dry ratio. This paper, was dried at 110°C for 20 hours and then divided
into eight parts. The longest reaction time was 42 hours. The maximum
nitrogen concentration attained in the reaction product was about 13%.
If on the average one cyanic acid molecule reacted with one anhydroglucose
unit, it would produce a nitrogen concentration of 7.0%, while two cyanic
acid molecules/anhydroglucose unit would result in a nitrogen concentration
of 11.3%, and three cyanic acia molecules/anhydroglucose unit would
result in a nitrogen concentration of 14.4%. The maximum fixation
achieved, then, was on the average 2.5 nitrogen molecules per anhydroglucose
unit; however it is very likely that prolonged exposure of the cellulose
to the heat resulted in some cellulose degradation so the nature of
the chemical bonding involving the nitrogen cannot be specified with
certainty.
The catalyst cupric chloride, at 5% of the weight of urea, has a
definite influence on the rate of nitrogen fixation as shown in Figure
III. C. 2. The paper was soaked in a 50% urea solution for two hours and
pressed to a wet/dry ratio of 4.4. The paper was dried at 110°C for
75
-------
20 hours prior to being heated to the reaction temperature. Four percent
nitrogen fixation was achieved during the drying operation. The rate
of nitrogen fixation was initially greater than with no catalyst, but
this rate decreased after about 4 hours.
The reaction temperature will affect the nitrogen fixation as shown
in Figure III. C. 3. Each sample contained 25 gins, of shredded paper that
had been soaked in a 19% urea solution and pressed to a wet/dry ratio
of 4. The mixture was dried in the reaction flask and the reaction time
was measured from the time the mixture reached the reaction temperature.
Heat was applied by use of a fluidized sand bath and the flask was rotated
to aid heat transfer within the flask. The reaction time for all states
was 1 hour. The level of nitrogen fixation increased as the reaction
temperature increased.
The urea concentration (measured as moles urea/mole cellulose)
in the reaction mixture has a definite influence on the nitrogen fixation
as shown in Figure III. C. 4. Each sample was prepared with 25 gms. of
shredded paper soaked in a urea solution. The urea concentration was
varied from sample to sample, and each sample was pressed to give a
wet/dry ratio of 4. The reactions were carried out in a rotating
flask heated by a fluidized sand bath. A copper chloride catalyst was
used at 10% concentration (based on weight of urea) and the mixtures
were heated at 190°C for 1 hour.
An increase in urea concentration resulted in an increase in
nitrogen fixation, however, the 1 hour reaction time may have been
the limiting factor in the 155°C curve.
Catalyst The effect of catalyst concentration (expressed as % of
Concentration the weight of urea used) on nitrogen fixation is shown
in Figure- III. C. 5. Each state contained 25 grams of paper which had
been soakct4 in a solution containing varying concentrations of catalyst
and dried at 110°C for 20 hours. The reactions were carried out in a.
rotating flask heated by a fluidized sand bath.
The mixture was heated to 155°C for 1 hour. Since a nitrogen
fixation of about 2% was; expected with no catalyst, it appears that
even small concentrations of catalyst (0.1-1.0%) have some effect on
the nitrogen fixation attained, but no effect was noted for concentrations
over 5%. In comparing Figure III. C. 2. and Figure III. C. 5., we find
less nitrogen fixed in Figure III. C. 5. This may be caused by a lack of nitrogen
available. This work needs co be re-run using greater urea concentrations.
Ammonia "Amino" cellulose was prepared from newspaper by reacting
shredded paper with ammonia in a Parr high pressure bomb at elevated
temperatures. The reaction temperature and pressure were varied, but
it was impossible to maintain the same reaction time for all runs because
of gas leaks. The results of this test are listed in Table III. C. 1.
It is not possible to know what contribution each of the variables
76
-------
made to the increase in nitrogen enrichment, but apparently the reaction
does not proceed readily at room temperature.
Nitric Nitric acid mixed with sulfuric acid was used to prepare
Acid cellulose nitrate containing 2.9%N from filter paper. No
attempt was made to evaluate the effect of variables on the degree of
nitrogen fixation.
Phosphorus Four samples of straw were soaked in a 21.5% phosphoric
Enrichment acid solution and drained to achieve a wet/dry ratio of 4.
The wet straw was heated in an oven'at 100°C for 64 hours. Two samples
were washed with water prior to the phosphorus concentration determination.
The results are listed in Table III. C. 2. Although some phosphorylation
has taken place, it is equivalent to an average of only one phosphate
group per two anhydroglucose units.
Nitrogen and Both nitrogen and phosphorus can be chemically fixed to
Phosphorus cellulose by reaction with urea and phosphoric acid. Although
Enrichment other reactions could also be used to accomplish this,
this was the only reaction used in this study. Both straw and paper
were used as a source of cellulose for these reactions.
Annual ryegrass straw was soaked in a phosphoric acid/urea solution
and filtered to remove the excess solution, to prepare samples with a
wet/dry ratio of 4.0. The filtrate from the first sample was replenished
and used for the second sample. This procedure was repeated except for the
fifth sample, which was soaked in the filtrate without replenishing.
The five samples were heated in an oven for 2 hours after drying. One
half of each sample was washed in water. The results are listed in Table
III. C. 3. On the average they contained 3.5% phosphorus and 5.0% nitrogen
or 3.2 moles of nitrogen/mole phosphorus even though excess phosphorus and
nitrogen were available.
Newspaper can be enriched with nitrogen and phosphorus by soaking
the paper in a 40/30/30 wt./wt./wt. solution of urea/85% phosphoric acid/
water and filtering the paper to give a 4.9 wet/dry ratio. Khen the mixture
is heated to 155°C for three hours and washed with water. The product
contains 5.0% nitrogen and 4.4% phosphorus.
Some of the variables in the process which might affect the nutrient
concentration are predrying, reaction time, reaction temperature, and reactant
concentration.
The effect of predrying the reaction mixture on nitrogen and phosphorus
fixation was determined by soaking two samples of paper in the urea/acid
solution. One sample was predried for 20 hours at 110°C while the other sample
was dried in the reaction chamber. Both samples were heated to 166°C for
160 minutes and then washed. The predried sample contained 6.1% nitrogen
and 3.5% phosphorus while the other sample contained 5.9% nitrogen and
3.6% phosphorus. These results show that predrying the wet paper did not
affect the results.
77
-------
The effect of reaction time on nitrogen and phosphorus fixation is
shown in Figure III. C. 6. Samples of shredded newspaper were soaked
in a 40/30/30 solution of urea/85% phosphoric acid/water and pressed
to a wet/dry ratio of 4.7. The reactions were conducted at 155°C in a
rotating flask heated by fluidized sand bath. After washing, the nitrogen
and phosphorus concentrations were determined.
Over the range used, the phosphorus concentration is not affected
by reaction time, but the nitrogen concentration increased slightly
with the longer reaction times.
The effect of reaction temperature on ritrog^n and phosphorus fixation
is shown in Figure III. C. 7. Samples of shredded newspaper were soaked
in a 40/30/30 solution of urea/85% phosphoric acid/water and pressed to
a wet/dry ratio of 4.0. Each sample was predried at 110°C for 16'hours
prior to being heated at the reaction temperature for 1 hour in an oven.
After washing, the nitrogen and phosphorus concentrations were determined.
The reaction temperature has a negligible effect on the degree of
phosphorus fixation although the nitrogen fixation increased at higher
temperature. Apparently most of the reaction occurred during the drying
step. This is surprising considering Nuessle's suggestion that the
urea (m.p. 133°C) acts as a solvent for the reaccion.
The effect of reactant concentration on nitrogen and phosphorus
fixation is shown in Figure III. C. 8. Samples of shredded paper were
soaked in a 40/30/30 solution of urea/85% phosphoric acid/water and
pressed to a wet/dry ratio of 3.0. The urea/phosphoric acid weight ratio
was constant at 4/3 for each soaking solution. After predrying the mixtures
were heated to 150°C for 3 hours. After washing the nitrogen and phosphorus
concentrations were determined. The degree of nitrogen and phosphorus
fixation increases as the reactant concentration increases, but there is
obviously an upper limit to the amount of nitrogen and phosphorus that
can be chemically united to cellulose.
Soil These tests were conducted using No. 10 size cans filled
Test's with soil. A mixture of the various ryegrasses was used
because of the response of these grasses to nitrogen in the soil. Enough
commercial fertilizer or enriched waste was used to provide 50 pounds of
nitrogen per acre. Approximately two weeks after the initial planting,
the grass was cut to a uniform height, and the grass clippings were weighed.
The grass was then cut each week for the duration of the test period.
The total glass production from each state is the total of the weekly
productions. All cans received the same amount of water and each can
had holes in the bottom for drainage. In each series of tests, two control
states were included, one with no fertilizer added and one with a sample
of commercial fertilizer providing 50 pounds of nitrogen per acre.
It is presumed that when the nitrogen in the treated waste is readily
available to the plant, the growth rate will be comparable to the state
78
-------
containing commercial fertilizer, while when the nitrogen in the treated
waste is not immediately available to the plant, the growth rate will be
comparable to the state containing no fertilizer. Finally when the
enriched waste has a deleterious influence on plant growth, the growth
rate will be less t'aan the control with no fertilizer. The "slow release"
of the treated waste was not determined by this series of tests.
The results of these tests are presented below.
Nitrogen enriched samples of waste cellulose were used in the soil
tests. The tests were conducted on samples enriched with urea, ammonia,
and nitric acid.
The effect of nitrogen enriched paper resulting from the reaction
of urea and cellulose on plant growth is listed in Table III. C. 4.
The use of the nitrogen enriched paper raised the plant growth rat .
slightly, on the average about 75% as much as the commercial fertilizer;
however, two samples showed an exceptionally high effect, over 90% as
much as the commercial fertilizers. Apparently the reaction product of
the dry mixture is different than the product that results when the
urea is dissolved, at least it appears to be more readily available to
the plant.
The effect of amino cellulose on plant growth is listed in Table III. C. 1.
Two of the samples apparently had a deleterious effect on the plant
growth rate. The product that had been reacted at the highest pressure and
temperature raised the plant growth rate about 40% as much as the commercial
fertilizer.
The use of cellulose nitrate did not appreciably affect the plant
growth rate.
The nitrogen and phosphorus enrichment influence on the plant growth
rate is listed in Table III. C. 5. The use of these samples resulted in
a significant increase in plant growth, on the average 130% as much as
that produced by the commercial fertilizer.
79
-------
References.
1. Anderson, J. W., "Preparation of Nitrogenated Fertilizers by
Treatment of Cellulosic Materials with Ammonia", Iowa State
Journal of Science, 26_, 158-159 (1952).
2. Barbour, J. F., "Cellulose Compounds Containing Nitrogen", Report of
The Department of Agricultural Chemistry, Corvallis, Oregon
June, 1951.
3. Barry, A. J., F. C. Peterson, and A. J. King, "Interaction of
Cellulose and Liquid Ammonia", Journal of The American
Chemical Society, 5£, 333-337 (1936).
4. Davis, R. 0. E., R. R. Miller, and W. Scholl, "Nitrification of
Ammoniated Peat and Other Nitrogen Carriers", Journal of
The American Society of_ Agronomy, 27_, 729-735 (1935).
5. Gallagher, D. M., "Phosphorylation of Cotton with Inorganic Phosphates",
American Dyestuff Reporter. 55(10), 23-25 (1964).
6. Lyons, J. W., The^ Chemistry and Uses of Fire Retardants, Wiley-
Interscience, New York, 1970.
7. Nikitin, N. I., The Chemistry of Cellulose and Wood, Isreal Program
for Scientific Translations, Jerusalem, 1966.
8. Nuessel, A. C., "A Note on The Reaction Between Urea and Cellulose",
American Dyestuff Reporter, 53(2), 26-27 (1964).
80
-------
.Solution
CD
Waste
-*•
Soak
Filter
Heat
Wash
Dry
Storage
Concentrate
Figure III. C. 1. Schematic Diagram of the Nitrogen-Phosphorus Enrichment Process.
-------
00
K)
10
(B) No Catalyst
15
20 25
Time (Hours)
30
35
40
45
Figure III. C. 2. The Effect of Reaction Time on Nitrogen Fixation in the Reaction of Cellulose and Urea
-------
4.
Of
£ 3
2
g
00
s
140
150 160 170 180
Reaction Temperature, °C
190
figure III. C. 3. Effect of Reaction Temperature on Nitrogen Concentration.
83
-------
0 0.5 1.0 l.S 2.0 2.5 3.0
Urea Concentration, Mole Ration Urea/Cellulose
Figure III. C. 4 Effect of Reactant Concentration on Nitrogen Concentration.
Time = 1 hr.
84
-------
00
in
I
01234567
Catalyst Concentration, % Urea Wt.
Figure III. C. 5 Effect of Catalyst Concentration on Nitrogen Concentration. (Cupric Chloride)
-------
6 •
(-1
*j
v
u
o .,
u 4
Phosphorus
1 234 56 7
Reaction Time (Hours)
Figure III. C. 6 Effect of Reaction Time on Phosphorus Concentration
o
•H J^
s
g 31
u
c
5
no
Phosphorus
120
, 160
170
180
130 140 1?0
Reaction Temperature (°C)
Figure III. C. 7 Effect of Reaction Tpmporsture on Phosphorus Concentration
86
-------
§2
2
«•>
g
u
0 0.2 0.4 0.6 0.8 1.0
Phosphoric Acid Concentration, Mole Ratio H,P04/Ce]lulose
Figure III. C. 8 Effect of Reactant Concentration on Phosphorus Concentration
87
-------
Table III. C. 1. Soil Test With Amino Cellulose
State i I
Reaction Pressure, P.S.I.
Reaction Temperature, °C
Reaction Time, min.
N Concentration (unwashed), %
Production, gms.
N Concentration, (washed), %
Production, gms.
132
23
900
0.8
10.5
0.3
5.7
900
90
10
1.7
17.6
0.9
7.1
980
185
30
4.1
13.5
3.1
10.2
2700
300
60
11.2
12.4
10.5
12.4
Standards
No Fertilizer — 9.5 gms., nono anaonium phosphate 31.4 gms.
88
-------
Table III. C. 2. Phosphorylation of Straw
Straw weight, grams
Phosphoric Acid, grains
Reaction Temperature, °C
Reaction Time, hours
Product Weight, grains
Product Weight (washed) , grams
Phosphorus Concentration, weight \
20
15.3
110
64
26.6
20.8
20
15.2
110
64
26.6
11.7
3.1
20
14.8
110
64
26.6
21.7
20
14.6
110
64
26.6
12.0
3.2
89
-------
Table III. C. 3. Nitrogen and Phosphorus Enrichment of Straw
Sample Phosphorus Concentration, Wt. % Nitrogen Concentration, Wt. %
Unwashed Washed Unwashed Washed
1
2
3
4
5
13.3
13.3
11.8
12.3
11.5
3.4
4.8
2.5
3.8
2.9
14.5
14.3
12.8
13.9
14.9
5.6
4.8
4.1
5.5
5.1
90
-------
Table III. C. 4. Soil Test Kith N-Enriched Paper
Reaction Time, (hrs) 50 110 111
Reaction Temperature, (8C) 155 - 155 155 - 145 145 ' 145
Washed, Unwashed (w,u) ww uww uuw
Nitrogen Concentration, (%) 3.8 0.1 10.2 1.6 0 12.2 12.2 1.7
Grass Production, (grams) 10.3 36.6 32.4 43.9 8.9 24.1 32.5 42.4
Standards
jo No Fertilizer 8.5 33.2 33.2 33.2 8.5 8.5 14.4 33.2
Commercial Fertilizer " 28.1 46.5 46.5 46.5 28.1 28.1 36.3 46.5
-------
Table III. C. 5. Soil Test With N and P Enriched Paper
State
Reaction Time, (hrs)
Reaction Temperature, (°C)
Washed, unwashed, (w,u)
Nitrogen Concentration, (%)
Phosphorus Concentration, (%)
Grass Production, (grams)
Standards
No Fertilizer
Commercial Fertilizer
1
1
155
w
7.3
4.6
35.3
14.4
36.3
2
4
155
u
i
13.1
1.1.7
31.5
6.5
31.5
3
4
155
w
5.1
8.7
63.4
6.5
31. ':
4
4
155
w
5.1
8.7
27.8
11.5
31.0
5
0.5
190
u
11.4
8.8
37.1
14.4
36.3
6
0.5
190
w
6.6
6.4
32.7
14.4
36.3
7
0.5
190
w
6.6
6.4
27.4
8.5
28.1
-------
Acetylation of Wastes
The first recorded acetylation of cellulose has been credited to Schutzen
berger (4:61) in 1865. However, the sulfuric acid catalyst used reacted
with the cellulose to form sulfate esters. These groups cause the product
to be unstable. Later it was found that by using a hydrolysis step, the
acetate could be converted to a more useful form.
A typical reaction scheme for the commercial production of cellulose
acetate can be shown as
cellulose
acetic acid § catalyst 4- acetic anhydride
esterification
4-
water in acetic acid
hydrolysis
4-
filtration
4-
wash and stabilize
4
dewater and dry
+
screening and packaging
Chemistry; There are several methods of esterification that can be
used to acetylate cellulose in the laboratory. Since cellulose contains
hydroxyl (OH) groups, it must be considered to be an alcohol, and will be
denoted by the usual symbol ROH. The acid will be noted as R-^-OH.
0
Reactions That In general there are four reactions that can be used to
Produce ITsters produce an ester. These reactions can be shown as:
93
-------
1. The reaction of an acid chloride with an alcohol
0
ii
R-C-C1 + R'OH •* RCOOR' * HC1
?.. An acid plus an alcohol using a basic catalyst
0
'< +
R-C-OH + R'OH + Base ^ RCOOR1 + H20
3. An acid plus an alcohol using an acid catalyst
° y.1
R-C-OH + R'OH + Acid ^ RCOOR' + H.O
V2
4. An anhydride plus an alcohol
0 0
n n
R-C-0-C-R + R'OH •*• RCOOR' + RCOOH
Reaction three is usually used commercially to produce cellulose acetate.
As shown, the reaction is reversible, and the velocity (v) of each reaction
depends on the rate constant and the concentration of the reactants and
products.
V1 = kx (RCOOH) (R'OH)
V2 = k2 (RCOOR') (H20)
It is easily seen that by using an excess of acetic anhydride to remove the
water, the reaction will be forced toward the formation of the ester RCOOR'.
It has been found that when using sulfuric acid catalyst, S% by weight of
the cellulose, a very rapid reaction takes place at the beginning of the
esterification producing sulfate esters. Because of the large concentration
of acetic acid, a transesterification occurs replacing the sulfate groups
with acetyl groups. Some sulfate groups remain even after long reaction
times. A hydrolysis step is employed to remove the sulfate groups.
Acetic acid, containing enough water to make the final solution to about
0.5% water, is added to the reaction mixture. This water not only
hydrolyzes the sulfate groups but destroys the excess anhydride as well.
This hydrolysis step should be fairly short, i.e., about 5 hours or less
because it has been found (2) that long hydrolysis times reduce the acetyl
content and again increase the sulfate content.
The usual laboratory procedure for preparing cellulose acetate for
esterification would be to soak the cellulose in water and replace the
94
-------
absorbed water with glacial acetic acid. This requires large quantities
of water and acid, and has been replaced in industry by simply soaking
the cellulose with acetic acid for 1-2 hours before acetylatJon takes place.
Several publications have reported the preswelling of the cellulose
with various materials to insure a more complete reaction. A fairly
recent paper by Klenkova et. al. (1) reported the preparation of cellulose
triacetate with high degrees of polymerization (1100-1150). They used
methylamine or ethylenediamine to preswell the cellulose. The amines
were subsequently removed with organic solvents then with acetic acid.
It is doubtful that this complicated process will be used by industry.
Malm et. al. (3) studied the far hydrolysed cellulose acetates, i.e.,
cellulose acetate with a large portion of the acetyl groups removed by
hydrolysis. They found the products to be soluble over a wide range of
acetyl content if they varied the water to acetone ratio in the solvent.
For example a 1:1 mixture of water and acetone (they did not state whether
this was mole %, weight %, or volume %) was capable of dissolving
cellulose acetates with an acetyl content from about 16 to 35%.
Catalysts Used Numerous acids and acid salts have been used in
In Esterifications the laboratory to produce cellulose acetate.
Typically one finds zinc chloride, perchloric acid, sulfonic acids,
various halogen acids, and sulfuric acid being used as catalysts.
Commercially sulfuric acid is used because of its reasonable cost and lack
of corrosion of the equipment used. Its use does require the hydrolysis
step however.
Basic catalysts are usually limited to pyridine or basic salts such
as sodium acetate.
Recovery Of Stannett (5:40) tells us that solvent extraction,
Excess Reagants followed by solvent distillation, is used to reclaim
the dilute acetic acid produced by the precipitation step of the acetylation
process. She suggests the use of ethyl acetate as a solvent because ethyl
acetate removes excess water as an azeotropic mixture. The ethyl acetate
is next to distill, and finally the acetic acid is removed at the bottom
of the column.
There are several alternate =civents that could conceivably be used,
but will not be listed here.
Process: Acetylation has been conducted on a laboratory scale using
the vapor phase, fiber, and solution processes.
Vapor A schematic diagram of the vapor phase process is shown in
Phase Figure III. D. 1. The cellulosic waste is placed in an oven
and hot air containing acetic anhydride vapors is circulated through the
oven. Since acetic acid is formed by the reaction, it can be condensed
from the exit gases. A catalyst, such as pyridine, must be used to
swell the fibers. Although this acetylation process does not produce a
95
-------
high degree of acetylation, it does improve dimensional stability in paper
and wood, and in laboratory tests it has produced adequate acetylation in
ground paper to form a solid disc on pressing.
Solid waste moisture content and nature of the solid waste will be
important in this process since the anhydride reacts with water to form
acetic acid and since the anhydride is being transported in the air. The
waste should be dried and ground because reduction in particle size will
increase the surface area and promote faster and more complete acetylation.
Catalyst selection is important in rate of reaction, cost, and recovery,
Pyridine is not the only catalyst that has been used in this process, but
it does have some advantages, in particular it is easily volatilized, and
it readily expands the cellulose fibers. The catalyst concentration will
undoubtedly have sorce effect on the availability of cellulose hydroxyl
groups f^r reaction.
Reaction temperatures must be controlled to maintain the greatest
yield at the least cost. If the reaction temperature is set below the
boiling point of acetic anhydride (~140°C), then the condensation of anhydride
on the cellulose will facilitate the reaction; however, if the temperature
is above the boiling point of acetic acid, (~118°C), then the acid formed
will immediately be vaporized. Since the boiling point of pyridine is
about HS^C, it will remain in the vapor state at these conditions. Reaction
temperatures above 140°C would insure that the anhydride remained in the
vapor state. In a batch reaction, the temperature could be maintained
above 140°C after the reaction to remove the excess anhydride.
The reaction time will determine the degree of acetylation until
the reaction is complete. The rate at which anhydride and catalyst is
carried to the oven will be determined by the air flow and air temperature.
The acetylation rate will be influenced by the oven temperature
and the availability of the cellulose hydroxyls. Sufficient reaction
time will be needed to produce an acetyl content that will allow the
cellulose to have thermoplastic properties.
The Fiber is schematically shown in Figure III. D. 2. The dry
Process cellulosic waste is reacted with a solution containing
acetic anhydride, a catalyst, and a solvent. Acetic acid and cellulose
acetate are produced by the reaction. The reaction solution is separated
from the acetylated waste solids. The solvent and catalyst are reclaimed
for reuse, leaving the acetic acid as a by-product. The acetylated
waste is then washed and dried. This process can be used to prepare
the triacetate by repeated acetylations of the product.
The solid waste must be dr/. Although the particle size is not as
important as in the vapor phase process, a reduction in particle size may
facilitate waste handling. The anhydride is carried to the cellulose by
the solvent, but the product iloes not dissolve in the acetylation solution.
Perchloric acid serves as a good catalyst for this process since it
does not combine with the cellulose, however it can be a hazard under some
conditions. Catalyst concentration will influence the rate of the
reaction.
96
-------
Several organic solvents have been evaluated for this process
including toluene, methylene chloride, and ethylene chloride. The solvent
prevents the cellulose acetate from dissolving and carries the acetic
acid away. The solvent can be reclaimed for reuse by removing the acetic
acid. The degree of acetylation will be determined primarily by the
concentration of acetic anhydride used in the acetylating solution.
This reaction will proceed at room temperature but normally a
temperature of about 50eC is employed. Since the reaction is exothermic,
the reaction temperature rises during the reaction and often reaches
50CC without the addition of heat. The reaction proceeds rapidly and a
complete reaction is usually achieved in less than 10 minutes.
After the reaction is complete, the acetylating solution can be
separated from the cellulose acetate by filtration or by centrifuging.
Since some solvent, remains in the cellulose acetate, an alcohol wash is
used instead of water. Ether can be used to remove the alcohol or it
can be evaporated. The resulting cellulose acetate is normally dried at
60°C.
Solution A schematic diagram of the solution process is shown in
Process Figure III. D. 3. The solid waste is reacted with a solution
containing acetic anhydride, acetic acid, and a catalyst, usually sulfuric
acid. The cellulose acetate produced dissolves in the acetylating
solution. Any solids left in the mixture can be removed by filtration. The
cellulose acetate is precipitated in water, and if it is passed through
tiny holes, it will form threads of the cellulose acetate polymer. The
solid is separated by filtration and any combined sulfate is neutralized
by addition of sodium carbonate. After further washing, the at?tate is
dried.
The solid waste composition is least important in this process,
since the acetate produced goes into solution. Of the three processes,
impurities which influence the reaction will have the most effect in
this one, however inert solids can be removed by centrifugalion or filtration.
The catalyst used in the laboratory was perchloric acid although
sulfuric acid is normally used. The catalyst concentration will affect
the nature of the product, since the sulfuric acid is a combining catalyst
and until hydrolyzed *he product is actually a mixed ester.
Experimental results: Cellulose acetate has been prepared in the
laboratory from samples of commercial refuse, paper, and straw. Three
acetylation processes have been used; vapor phase, fiber, and solution.
Vapor Phase Two samples of paper were acetylated using the vapor phase
Process process. Hot dry air (120°C) was passed through acetic
anhydride to pick up vapors then was passed through a flask containing
the paper. The catalyst, pyridine, was dissolved in the anhydride.
The reaction was allowed to continue for 2 hours at 120°C and then the
97
-------
excess anhydride was driven off at 150°C for 12 hours. After washing
and drying the paper was compressed with 2,000 p.s.i. at 350°F to form
a plastic disc.
The weight gain for each of the two samples was 22% and 31%,
respectively, approximately equal to that expected for formation of the
monoacetate (26%).
Fiber A study of the effect of variables on the degree of acetylation
Process in the fiber process conducted using various samples of
cellulosic wastes. The results of these tests are reported below.
Cellulose swelling with water or other chemicals speeds the reaction.
Presumably, when the cellulose is "activated", or swollen, prior to
reaction with the acetic anhydride, the internal cellulose hydroxyls
are made available to the anhydride. The effect of swelling the fibers
on the extent of acetylation was determined using 2 samples of filter
paper.
One sample was soaked in water and the water was then replaced by
acetic acid prior to reaction with the anhydride. The other sample
was dried at 110°C prior to reaction. Both samples were acetylated
using perchloric acid as the catalyst. The activated sample resulted in
a gain in weight of 56% while the non-activated sample resulted in a gain
in weight of 55%. Both products were soluble in a 90:10 wt./wt. dichloromethane/
methanol solution. A 52% increase in weight would be equivalent to the
formation of cellulose diacetate. Under these reaction conditions, soaking
the cellulose did not affect the degree of acetylation achieved.
In a similar test, using toluene as the solvent, a different result
was obtained. When no acetic acid was present in the toluene and the paper
was not preswollen, cellulose acetate with only 12% acetyl content was
produced after 20 minutes reaction time, compared to an acetyl content of
23% when DCM was used as the solvent.
When acetic acid was added to the toluene a cellulose acetate with
28% acetyl was obtained after only 2 ninutes reaction time.
When the cellulose was preswollen with water and the water replaced
with acetic acid, the reaction in toluene produced an acetate with 35%
acetyl, while the reaction in DCM produced an acetate with 30% acetyl.
From this evaluation it appears that "activating" the cellulose does
have an influence on the degree of acetylation achieved; however, the
effect is different for different solvent systems. In addition, the presence
of acetic acid in the solvent influences the degree of acetylation,
although this effect is also different for different solvent systems.
Reaction time influences the degree of acetylation as shown in Figure
III. D. 4. This evaluation was conducted with a sample of commercial
paper waste obtained from a Seattle bank. The waste was dewatered with
98
-------
acetic acid and reacted with a solution containing toluene, perchloric acid,
and acetic anhydride. After the reaction was complete, the solid acetate
was separated by centrifuging. Ethanol was used to remove the toluene and
the cellulose acetate was washed in water and dried. Under the conditions
of this test, changes in the reaction time did not affect the degree of
acetylation.
A second evaluation was conducted to determine the effect of changes
in time from 1 to 10 minutes. The results of this test are shown in
Figure III. D. 5. Although the degree of acetylation increases with
increasing time, a plateau occurred at about 5 minutes reaction time.
This plateau corresponds to a degree of substitution of about 1.5 - 1.8.
It appears that the introduction of the third acetyl group is somewhat
more difficult than the first two.
Anhydride concentration affects the degree of acetylation as shown in
Figure III. D. 6. This evaluation was conducted with a sample of
commercial paper waste obtained from a Seattle bank. The waste was
dewatered with acetic acid and reacted with a solution of toluene, perchloric
acid, and acetic anhydride. After the reaction was complete, the solid
cellulose acetate was separated by centrifuging. Ethanol was used to remove
the toluene and the cellulose acetate was washed with water and dried.
An increase in the anhydride concentration resulted in an increase in
the decree of acetylation but only 50-70% of the .anhydride reacted.
A second evaluation conducted with newspaper confirmed these results.
Based on these findings, an anhydride concentration of 2 moles anhydride/
mole cellulose would be required to produce the monoacetate, which is
the level required in order to impart a thermoplastic property into the
product; however, cellulose acetate with .209- acetyl can be prepared
withouth any anhydride. Two reactions conducted with acetic acid only,
for 1 minute and 14 hours respectively, resulted in products with acetyl
concentrations of 13% and 20% respectively, however the physical properties
of these products were not determined.
A reaction temperature increase will increase the degree of acetylation.
An evaluation of this effect was conducted using a sample of commercial
paper waste obtained from a Vancouver brewery. It was uewatored with
acetic acid and reacted for 5 minute.; with a solution containing 150 ml
toluene, 15 ml acetic anhydride, and 0.15 ml perchloric acid. Cellulose
acetate samples with 41.6% and 39.0% acetyl respectively were produced.
Catalyst concentration will influence the degree of acetylation as
seen In Figure III. D. 7.these reactions were carried out using a sample
of commercial paper waste from a Vancouver, Washington brewery. The water
was replaced with acetic acid and the reaction was conducted with a solution
of toluene, acetic anhydride, and perchloric acid for 1? minutes at 25°C.
The acetic anhydride concentration was 3.7] moles anhydride/mole cellulose.
The acetyl concentration is reduced when the catalyst concentration is
reduced below 1% of the acetic anhydride weight.
99
-------
The product that was.obtained with the use of DCM as solvent exhiMts
extremely good flow properties in the plastic state. This flow property
is not exhibited by acetate made with toluene or made by the solution process,
however, removal of the DCM is a problem.
Solvents used in conjunction with the acetylation reaction have a
pronounced affect on the results. Since toluene prevents dissolution of
the cellulose acetate, it is a solvent only in that it holds the anhydride
and catalyst in solution. Because the cellulose does not dissolve in the
reaction mixture, the acetate can easily be recovered from the reaction
mixture by filtration or centrifugation. The solvent mixture can then be
recycled or subjected to a reclamation process. The solids from this
process need less water for washing because methanol, which is at least
in part reclaimable, is used to remove the residual toluene and acids.
Following separation, the reaction mixture can be distilled and the
distillate returned to the system as a starting material for further
acetylations. The first portion of the distillate contains an acetic
acid-toluene azeotrope, boiling at 104°C. As the toluene is depleted,
the temperature of the distillate increases and there is more anhydride
present. When the acetic acid has completely distilled, acetic anhydride
can be recovered.
The methanol used for the wash is more difficult to reclaim. Traces
of acetic acid and acetic anhydride washed from the acetate react with
the methanol to form methyl acetate. When this mixture is distilled,
the first portion contains methanol, methyl acetate and toluene, then as
the toluene is exhausted, the raethanol-methyl acetate azeotrope distills.
Finally, as the methyl acetate is exhausted, the pure luethanol can be
reclaimed by di illation. The methanol-methyl acetate azeotrope could be
converted to methyl acetate, which would have utilization as a solvent for
introducing the plasticizers into the cellulose acetate.
When dichloromethane (DCM) is used instead of toluene, the reaction
mixture becomes very gummy and is not filterable, however the solid can be
separated by centrit'uging.
The waste source has a strong influence on the maximum acetyl concentration
obtainable. Filter paper, produces a white powder with up to 44% acetyl
content. This material can be formulated and ca^ndered into transparent
sheets. As the impurities in the starting material are increased, the
product loses its transparency and becomes darker in color.
Newspaper, which contains some lignins produces a light brown
cellulose acetate with 42% acetyl content, while municipal refuse produces
a dark brown cellulose acetate with 36% acetyl content. This latter
sample of municipal refuse was obtained from the Black-Clav/son Company
in Ohio, ar.d still contained small pieces of inorganic residue although
most of the metal and glass had been removed.
100
-------
Solution Cellulose acetate was prepared from paper and straw
Process using the solution process, but an extensive evaluation of
this process was not undertaken since the vapor phase and fiber processes
appear to be better suited for chemical treatment of waste cellulose to
produce cellulose acetate.
Straw, when acetylated gives a product which is dark brown, brittle,
and contains straw components that are not dissolved.
Paper was used in a series of tests to evaluate the effect of
changes in catalyst concentration on the degree of acetylation when using
samples of newspaper as the source of cellulose. The amount of catalyst,
perchloric acid, was varied from 0.16% to S% by volume, based on the volume
of acetic anhydride used. One series of samples was prepared at a reaction
time of 1 minute while another series was prepared at a reaction time of
30 minutes.
Perchloric acid, while somewhat more hazardous to use than sulfuric
acid, was chosen as the catalyst because it eliminated the need for
hydrolysis between the acetylation and the precipitation steps in the
solution reactions. Perchloric acid does not form esters with the
cellulose as sulfuric acid does. The sulfate esters not only lower the
degree of acetylation of the final product, but because of their acid
nature, these esters cause hydrolysis of the acetate esters when exposed
to atmospheric moisture.
101
-------
References
1. Klenkova, N. I., 0. H. Kulakova, N. D. Tsimara, N. A. Matveeva, and
E. M. Khlebosolova, "Preparation of Cellulose Triacetates of High
Degree of Polymerization", Journal of Applied Chemistry of U.S.S.R.,
41_, 592 (1968).
2. Malm, C. J., L. J. Tanghe, and B. C. Laird, "Preparation of Cellulose
Acetate, Action of Sulfuric Acid", Industrial anc[ Engineering
Chemistry, 3£, 77 (1946).
3. Malm, C. J., K. T. Barkey, M. Salo, and D. C. May, "Far-Hydrolyzed
Cellulose Acetates", Industrial and Engineering Chemistry, 49, 79 (1957).
4. Schutzenberger, P., "Action de 1'acide acetique anhydre sur la cellulose",
Academic de_ Sciences, Comptes Rendes, 01, 485 (1865).
S. Stannett, V., Cellulose Acetate Plastics, Temple Press Ltd., London (1950).
102
-------
o
w
Solid Waste
Acetic Anhydride
Pyridine
vapor
phase
Oven
Acetic Acid
Pressing
Figure III. D. 1. Schematic of Vapor Phase Acetylation of Solid Waste.
-------
Acetic Anhydride
Solid Waste
Acetic Anhydride
Catalyst
Solvent
Acetylation
Acetic Acid
Catalyst
Solvent
Filter
->J Acetic Acid
Wash
and
Dry
Storage
Figure III. D. 2. Schematic Diagram of The Fiber Process of Acetylation of Solid Wastes.
-------
o
in
Solid Waste
Acetic Anhydride
Acetic Acid
Catalyst
I
Reactor
Reclaim
Water
Filter
|
Solids
i
»
Hydroli.se and
Precipitation
Acetic Acid
i
Filter
1
Storage
Dry
Wash.
Stabilize
Na2C03
Figure III. D. 3.' Schematic Diagram of The Solution Process for Acetylation of Solid Waste.
-------
60
50
c
-------
50
40
g
+J
X
4-)
u
30-
20
-f-
8
—. DS=3
DS=2
DS-1
1234567
Time (minutes)
Figure III. D. 5 Effect of Reaction Time, from 1 to 10 Minutes, on Degree of Acetylation.
10
-------
12 345
Acetic Anhydride Concentration, (Mole ratio Anhydride/CelluJose)
Figure III. D. 6 Effect of Anhydride Concentration on Acetyl Content.
108
-------
o
US
V
O
X
*->
u
u
50
40
30
20
10
» I
1.0 2.0 3.0
Mi111liters of 70% HC104 Mixed with 60 ml. of Acetic Anhydride
Figure III. D. 7. Showing the Relationship Between Catalyst and Degree of Acetylation When
Using Perchloric Acid, with a Reaction Time of One Minute.
-------
Hydrogenation of_ Wastes
"Future Fuels; Where From" was the title of an article (30) describing
one of the problems facing this nation. It is felt t'.i, this problem can
be partially solved along with the problem of the refuse crisis, by converting
the wastes to gas and oil through hydrogenation. Liquid fuels are easier
to transport and presumably have a higher energy value than the solid
fuels.
In 1966 a preliminary literature search concerning the problem of
our fuel shortage was undertaken. It was found that Glover (38) and Linsly
(62) both reported that the use of gas and oil was outstripping the
development of new reserves. They stated that this condition had existed
since 1958. By 1970 the news media had taken up the hue and cry about
the energy crisis (34, 84). Even the oil journals were admitting that
the demand was increasing so rapidly that by 1990 the world demand for oil
would be 100 million barrels per day (90).
By 1967 some people were beginning to look toward controlled nucleai
reactors as a source of electric power which would relieve some of the
strain on the gas, oil, and coal reserves (86, 87). Other are convinced
that conversion of coal to oil and gas is the answer to the energy shortage
(27, 28, 29, 70). A relatively new concept is the atomic "mining" of a
gas and oil from oil shale and oil sands. (69, 71). Thermal processing of
shale and sand is being examined in attempt to bolster our sagging reserves
(31).
In the past 5 years there has been no reported gain in the reserves to
production ratio for either gas or oil. In fact the reserves to production
ratio is still reported to be declining (40).
Chemistry: Man in his search for an understanding of the world in
which he lives has done much toward finding the answer to how coal and
oil could have been formed. In 1913, Heuser (44) found that a coal-like
substance was formed in the digester system at a pulp mill. In 1922
Willstatter and Kalb (88) studied the reduction of carbohydrates and lignins
by the action of hyclriodic acid and red phosphorus. In 1923, Fischer
and Tropsch found that iron acting as a catalyst would produce hydrocarbons
from carbon monoxide and hydrogen (80).
Berl and his co-workers published several papers on the formation of a
coal-like substance from celluiosic compounds, and the conversion of this
"coal" and carbohydrates to oil (10, 11, 12, 13, 14, 15, 16, 17, and 18).
They reported that the most positive results toward coal formation resulted
when the material was treated under pressure in an alkaline medium (13).
The "protoproduct" was subsequently treated with "ferrum reductum" and
iodine under 100 atmospheres of hydrogen (16, 17) to produce an oil. In
another article Berl (15) postulated the formation of aromatics and polycyclic
aromatics from carbohydrate molecules. Other references to Berl and his
co-workers would have to include the journals Papier-Fabrikant (18:141-149)
and Zcitschrift fur Physikalische Chemie (14:71-93).
110
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About 1935 there was a flurry of work reported by Boomer et al.
(21, 22, 23, and 24), in which they hydrogenated various substances in
tetralin and similar media. It was reported that the "oil" from the treatment
of grain screenings was very odorous, acid, contained conjiderable oxygen
and darkened rapidly (24:353).
Kurihari and Yoshioka (59) reported the production of gasoline by
hydrogenation of the oil produced from the hydrogenolysis of a mixture of
peat and tetralin. Hcnze, Allen, and Wyatt (43) treated cotton hull
fibers with base then hydrogenated the product. They found that 7%
base gave the best results. Geerards et al. (37) reported the hydrogenation
of carbohydrates.
More recently Ichikawa et al. (49) formed C^-Cg hydrocarbons from CO
and H2 by using electron donor-acceptor complex films as catalysts.
Appell, Wender, and Miller of the Bureau of Mines reported the
conversion of urban refuse to oil using the water-gas shift to hydrogenate
paper (2). They reported a yield of 41% oil. This oil from paper had a
relatively high, 20%, content of oxygen (2:4).
Much work has been done in the field of partial hydrogenation of
carbohydrates. In most cases the products are polyalcohols although
hydroxyketones have been reported by Gurkan (41). Belandin et al. (6,
7) used Ruthenium on a carrier in the presence of mineral acids to produce
sorbitol. Van Ling and Vlungter (85) produced polyalcohols, reporting
the analysis of these polyols by gas chromatography and paper chromatography.
Haidegger et al. (42) produced sorbitol by the reduction of glucose with
ammonia synthesis gas.
Kasehagen (55) obtained a patent for the production of glycerol from
reducible sugars. A year later Van Ling and Vlungter (85) also reported
the formation of glycerol thiouyh the hydrogenolysis of saccharides.
Bizhanov et al. (19) reported the use of a catalyst, consisting of nickel,
aluminum, and iron with about 2% manganese added, to hydrogenate monosaccharides.
Lignin and lignin containing compounds have been hydrogenatod by
several methods. Besides the earlier mentioned work of Berl and his
co-workers we find th?.t Peterson (68) obtained aldehydes, acids, and
phenolic compounds from the hydrogenolysis of bark using Raney nickel as
the catalyst. Rieche et al. (76) used MnC^-Fe^Os to hydropenate lignin.
Matsukura and Sukakibara (65), and Ohta and Sukakibara (65) examined the
products from the hydrogenolysis of protolignin and reported finding
substituted phenylpropane and substituted phenylpropanol. Pepper and Lee
(67) have reported a study of catalysts tor lignin hydrogenolysis.
Temperaturs Blackwood, McCarthy, and Cullis (20) published a paper on
Effects their study of the carbon-hydrogen reaction with coke
and chars. They stated that the reaction of coal with hydrogen was
111
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dependant on temperature treatment history and not on the source of the
coal. They were primarily interested in gasification rather than liquefaction
of the coal.
Dehydrogenation was noted by Benson and O'Neal (9:515) while studying
the kinetics of the reaction of alkyl iodides with hydrogen iodide. They
noted that the alkyl iodides are unstable at elevated temperatures, possibly
forming free radicals. Raley et al. (75), Mullineaux and Slaugh (64) and
Slaugh et al. (79) conducted a study of high temperature dehydrogenation
of hydrocarbons using iodine as a catalyst. They concluded that the reaction
probably proceeded through an aliphatic free radical mechanism. H&dgson
(45) also studied the reaction of iodine with various organic compounds
at high temperatures and found that a dehydrogenation occurs at temperatures
above 350°C. Adelson et al. (1) published the kinetic data for reaction
rates and the rate constant for the dehydration of isopentane by iodine
in the presence of oxygen at 500°C. They postulate 19 steos in the reaction.
Pyrolysis products are similar to many of those found in the hydrogenations
referred to earlier in this paper. Many listed products which were very
similar to those listed by Hurd (48:270-289) for destructive distillation
of cellulesic compounds. Hurd (48:282) lists alcohols, acids, ketones,
aldehydes, phenolics, hydrocarbons, gases, water, and charcoal as the
products of destructive distillation.
Goos (39:846-850) lists 213 compounds from the destructive distillation
of wood, including such items as hydrocarbons, aldehydes, amines, esters,
ketones, acids, anhydrides, alcohols, and phenols. Hoffman (47) pyrolyzed
municipal refuse at 900, 1200, 1500, and 1700°F. He published values for
gas, pyroligneous acids, and ch?r produced, as well as an analysis of
the composition of ths gas.
Orphey and Jerman (66) studied the liquid condensates from the
pyrolysis of municipal refuse reporting aldehydes, ketones, chloroform,
acids, water, aromatics, and phenolic compounds. Jerman and Carpenter
(53) reported the analysis of the gaseous components from the pyrolysis
of solid municipal refuse. They found H2, 02, N'2, CH4, CO 0)2, C2H4 and
C2H, to be present. They also reported a wide variation in the gas
composition from one sample to another, for example the amount of CH4
reported ranged from 0.2 to 16.14 volume percent.
Arseneau (3) studied the competitive reactions in the thermal
decomposition of cellulose and concluded that in the range of 200-280°C
depolymerization occurs. He suggests that one reaction of cellulose at
elevated temperature might be shown as:
H H
Cellulose - H,0 -»• C=C "*" C-C
I " I I! . __ '
OH H 0 .-
112
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Arseneau's work supported the earlier work of Kilzer and Broido (56).
Catalysts Used Bowen and others, in 1925, reported that the thermal
In_ Hydrogenations decomposition of cellulosics was not influenced by
the presence of hydrogen unless a nickel catalyst was used (25). Fierz-David
and Hannig (36) substantiated these findings, buc reported that even with
nickel catalyst there were aldehydes, ketones, arid phenols in the "oil".
Bowen and Nash published again in 1926 saying that nickel on alumina was
an excellent catalyst. They reported yields of oil up to 45.6 per cent,
using nickel oxide catalyst. In their analysis they found 9.21% phenol,
6.41% base, and an oil which, while not identified, was reported to have
a "paraffin like" smell.
For many years hydrogenation of coal to form an economical, liquid
fuel has been a challenge. Cochrait and Sayer (32) in 1959 reported that
the results of the work at Billingham indicated this process was not
economically realistic. Yet in 1967, Chemical and Engineering News
(70:96-98) carried an editorial stating that a method for converting coal
to gasoline was in the final stage of development. They gave son;e very
interesting economic and engineering figures which indicated that at best
the process would be marginal. Laying and Hellwig (60) have reported
on the H-Coal process. Coal hydrogasification (8), hydrogenation (58, 54),
and fluid bed hydrogenation (89) were all subjects of publications in
1970. Struck et al. (81) studied the kinetics of hydrocracking of coal
extract using molten zinc chloride catalyst. Hodgson (46) used a combination
of catalysts for the hydreconversion of coal. Lee et al. (61) published
on the heat of reaction of hydrogen and coal, Szucs (82) found that iodine
promotes the catalysts used in the hydrogenation of coal. Jachh (51)
states some of the problems found in the hydrogenation of coal.
Schlinger and Jesse (77), Flinn and Sachsen (35), Bae (4), and
Schultz and Linden (78) all have used hydrogen treatment of oil shale
for oil recovery.
Quader and Hill (73, 74) have published on their study of the hydro-
cracking of coal tar, as has Janardanerao et al. (52). An editorial in
Chemical Tn^ineer (50:50) stated that iodine catalyst improves coal tar
hydrogenation.
Experimental Results: A large number of reactions were carried out
under varied conditions. The use of different catalysts, various wastes,
and two separate gas mixtures was employed.
Catalysts Several catalysts and catalyst combinations have been
Used III used in the laboratory for the study of the hydrogenation
Hydrogenation of refuse. Raney nickel, palladium, iodine, hydriodic
acid, stannous chloride, tetrahydronaphthalene, and carbon monoxide-water
have all been used singly or in combinations to attempt hydrogenation. The
greatest yield of hydrocarbon oils was obtained using hydriodic acid.
113
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With Raney nickel, palladium, tetrahydronaphthalene, and the C
reactions, sizable quantities of oxygen containing compounds were found
to be present in the "oil". These oxygen compounds included groups such
as alcohols, ketones, acids, phenols and so on. With hydriodic acid the
amount of oxygen containing material was greatly reduced. Some phenols
were present, especially in wastes such as bark, straw, etc., which
contain lignins.
Recovery of the cata]yst from the hydriodic acid runs has been given
a cursory examination. In run W6-70-27 about 62% of the HI was recovered
in the water layer separated from the oils. Some of the iodine appears
to be in the form of organic halides, and some has been found as nearly
insoluble material in the solid residue. This latter material may be
polymeric in nature with iodine incorporated into the macromolecules.
Materials A wide spectrum of waste materials have been examined to
Treated determine their potential as sources of oil and gas, for
fuel, and of petrochemicals. Because municipal refuse is more than half paper,
work was started using a fairly pure grade of filter paper, then news print
was used for comparison, and finally waste bark and straw were examined.
Waste wood from the timber industry is a problem in the Pacific
Northwest, and since much wood is dumped in landfills by the construction
industry the feasibility of hydrogenating wood and wood by-products such
as bark was examined.
In some seasons large amounts of leaves and grass clippings are
hauled to landfills by the collection agencies. Locally there is a
problem with grass seed straw being burned; the examination of straw as
a source of oil and gas was therefore undertaken.
Rubber tires are becoming a great problem especially since many
landfills now refuse to accept these carcasses. Upon treatment under
hydrogenation conditions a gas and an oil were obtained. About 50 weight
percent of the rubber was found to be inert materials such as carbon
black, fillers, metal and so on. It may be possible to return the inert
materials to the industry for reuse.
Polyethylene was treated in the high pressure hydrogenation apparatus.
Although some of the other wastes contain small amounts of plastic, only
polyethylene was specifically treated. The results were not gratifying.
At the reaction temperatures used, the only results noticeable were the
melting and fusing of the pieces of plastic into one solid mass.
Head Ga£ After a brief examination of the oils from several hydrogenation
Analysis runs it was decided to examine the head gas in detail first
since the gas was less complex. The main components of the gas were
carbon dioxide (C02), carbon monoxide (CO), methane (0114), hydrogen 0^)
and variable amounts of light hydrocarbons, C2-C5, of both olefinic and
aliphatic nature. In reporting the information the methane and light
hydrocarbons are simply reported as hydrocarbons.
114
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Comparison of the head gas compositions from a series of runs to
determine the effects of hydrogen and of catalyst are shown in Table
III. E. 1. If one looks at run W6-70-28 using CO and 1^0 for hydrogenation,
one finds a high CO content in the head gas as would be expected because
of the excess CO introduced. The same is true of the hydrogen in the
hydrogenation runs.
Since large volumes of gas were used, a collection train was set up,
Figure III. E. 1., for the gross examination of the gas and a gas chromatograph
was used for the more careful analysis of the component content of gas.
However, since hydrogen was used as the carrier gas, and a hydrogen flame
detector was on the chromatograph, determination of the hydrogen present in
the gas samples was not possible by the gas chromatographic process.
Figure III. E. 1. represents the gas trapping and analysis train.
A is the connection to the bomb. 1B_ is a base filled bubble scrubbing trap
for the trapping of carbon dioxide. Trap C_ is cooled by a dry ice-acetone
refrigerant, while traps D_ and E_ are cooled by liquid nitrogen. Point F_
is a gas sampling port where samples are taken periodically for gas
chromatographic or carbon monoxide analysis, Figure III. E. 2. The gas
buret, G, indicates the uncollected gas which is primarily hydrogen.
Figure III. E. 2. represents the carbon monoxide analysis train which
consists of two traps filled with ammoniacal cuprous chloride solution
described by Bach, Dawson, and Smith (5). A 200 milliliter gas tight syringe
was used to remove samples from the gas collection train in Figure III. E. 1.
point F_ and transfer the gas for introduction at point F_ in Figure III. E. 2.
The cuprous chloride solution was standardized with known mixtures of gases
generated in this laboratory.
Figure III. E. 3. represents the gas chromatographic - mass spectrometric
analysis system. The gas chromatograph could be used directly in conjunction
with the mass spectrometer or used independently when desired. Samples
were removed from the gas trapping system at point F_, Figure III. E. 1. by a
gas tight syringe and subsequently injected at point F_ on the chromatograph,
Figure III. E. 3. '
After the gas from the bomb has been released through the gas train,
the valve at A_, Figure III. E. 1. is closed and the refrigerants are
removed to allow, the CO, CH4 and hydrocarbon gases to be measured and the
analysis recorded.
Gas chromatography of the head gas was accomplished using a Varian
1500 gas chromatograph equipped with a 20 foot long, 1/8 inch diameter
aluminum column packed with S% SE-30 silicone rubber on Chromasorb W
60/80 mesh. The oven temperature was maintained at 35°C throughout the
sampling of the head gas. Standards v
-------
Oil One of our very early hydrogenations was of the relatively
Analysis complex material, wheat straw. A sample of the oil was
injected onto the gas chromatographic column and the resulting chromatogram
revealed 66 peaks. One can quickly see that the oil from these hydrogenations
is very complex and difficult to identify.
A less complex material, glucose, was chosen since this is one of
the basic units of cellulose. The chromatogram at the oil from hydrogenation
of this material gave 59 peaks of which 9 could be considered to be major
peaks. This again confirms the complexity of the oil.
A sample of oil from Douglas Fir bark was sent to Standard Oil
Company and their results are given in Table III. E. 3. They stated in
the cover letter that small amounts of material were distilling at 600°F
so that a dry point could not be accurately determined.
When subjected to normal extraction analysis, the oil from the
hydrogenation of hospital waste was found to contain primarily hydrocarbons
with very small amounts of ketones, aldehydes, and phenols, and trace
quantities of acids and amino acids.
Oil from paper contained mostly hydrocarbons, although traces of
alkylhalides as well as small amounts of phenolic compounds were detected.
Berl et al. (15) postulated that aromatic and phenolic compounds could
be formed by the dehydration of glucose type molecules.
Grass straw produced an oil containing alcohols and alkylhalides in
small quantities; with the majority of the oil being hydrocarbons. A
modified FIA (Fit rescent Indicator Absorption) anclysis (33) of the oil
from straw indicated the presence of aliphatics, aromatics, and small
quantities of olefinic-compounds.
Volume percents were not determined since the apparatus we were using
was not of the smaller dimensions indicated by Knight and Groennings
(57:1950). The silica gel used was Davidson 923, 100-200 mesh, to meet
ASTM standard D 1319-61T, and was purchased from Fisher Scientific Co.
The oil from the CO-l^O treatment of straw contained considerable
amounts of strong acid, amino acids, aldehydes, ketones, alcohols, and
phenols. By thin layer chromatogiaphy and gas chromatography five of the
seven phenolic compounds were tentatively identified as: p-cre-»ol,
p-ethyl and p-methyl guaicol, p-ethyl and p-propylphenol. Standards were
not available to match the other compounds present.
Oil produced from treatment of straw with hydrogen and tetrahydronaphthalene
(THN) contained large quantities of naphthalene and THN. Gas chrom..ttgraphy
in conjunction with the mass spectrometer led to the identification of
benzene, toluene, cyclohexane, l-methyl-2-ethyicyclopentane, n-butyl
benzene, l-methyl-2,3-dihydroindene. Several additional compounds have
not been definitely identified but most had a peak at mass 31 which is
116
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indicative of the presence of a primary alcohol -r-ouping. Upon examining
the identified compounds one can see that there s a possibility these all
came from rearrangement and breakdown of the THN. It is suggested that
any further work with this material should include a treatment of THN
without any waste being present.
Table III. E. 2. gives the weight of residue per weight of cellulose,
the weight of water per weight of cellulose, the weight of the oil produced,
and the percentage of oil found in various boiling ranges. The products
from run W6-70-28 were very similar to those from the reaction with hydrogen
without catalyst present, including the percentages of oil found in each
boiling range.
The oils from the carbon monoxide (CO)-water reaction, the hydrogen
only run, the water only run, and the HI run were all similar in qualitative
composition. Although the quantitative analysis has not been completed,
the preliminary work indicates similarities in several of these oils.
The amount of carbon monoxide and carbon dioxide found in the gas,
when methyl iodide was used as a catalyst, was greatly reduced but the
amount of oil was not appreciably increased.
The oil samples were run either on the Varian 1520 or on a Varisn
1200 gas chromatograph which can be used in conjunction with the mass
spectrometer. The mass spectrometer is a V;i; 'an M.A.T. CH7.
The columns used were each 20 feet long by 1/8 inch outside diameter
aluminum tubing. One column was packed with 8% SE 30 silicone rubber on
Chromasorb W 60/80 mesh. The other column vas packed with 10% carbowax
20M on Chromasorb W 60/80 mesh.
The temperature was programmed according to the liquid phase and the
boiling range of the oil. The crude oil was run on the SE-30 packed
column, and the temperature was programmed from 50 to 200°C at 4° per minute.'
Material The material balance was examined for several of the runs,
Balance Table III. E. 4. If one looks at the oxygen balance, that
is oxygen in versus oxygen out, one finds an oxygen loss for all hydrogenations
except W6-70-23 and W6-70-27. Since the oxygen balance was primarily
determined for the head gas and water, we must assume that the remainder
(loss) is to be found in the oil. This is substantiated by the finding of
aldehydes, ketones and phenols in the oils.
Run W6-70-23 is difficult to explain because of the large apparent
gain in carbon. The carbon balance was determined by gas analysis and
by calculating the oil to be totally composed of hydrocarbons. Any oxygen
in the oil would therefore appear as an apparent gain in carbon in the
oil. It becomes apparent that a full material balance is impossible
unless the oil is quantitated for C, H, N, S, and 0.
117
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It does appear that the oil produced in run W6-70-27, hydrogenated ii
the presence of hydriodic acid, contains little oxygen. The 5.4% loss
of carbon in the carboi, balance may well fall within the limits of experin
error for the handling techniques. The variations in carbon balance in
runs W6-70-24, W6-70-26, W6-70-29, and W6-70-30 would indicate about
5% error was probable.
118
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54. Johanson, E. S., S- C. Schuman, H. Stotler, and R. H. Wolk, "Coal is
Catalytically Hydrocracked", Chemical Abstracts, 73_:57818j
(1970).
55. Kasehagen, L., "Hydrojjenolysis of Reducible Sugars *o Obtain a High
Percentage of Glycerol", U.S. Patent 3,396,199 (06 August
1968). Chemical Abstracts. 69j786C9z (1968).
56. Kilzer, F. J., and A. Broido, "The Nature of Cellulose Pyrolysis",
Pyrodynamics, 2(2-3) , 151-163 (1965) Chemical Abstracts,
63:8599a (1965).
122
-------
57. Knight, H. S. and S. Groennings, "Fluorescent Indicator Adsorption
Method for Hydrocarbon Type Analyses. Application To Traces
and Heavier Distillates", Analytical Chemistry, 28, 1949-1954
(1956).
58. Krichko, A. A., "Catalytic Hydrogenation of Coal", Chemical -Abstracts,
72;123747t (1970).
59. Kurihari, K., and A. Yoshioka, Society of The Chemical Industry
of Japan. 44_, 250 (1941).
60. Layng, E. T., and K. C. Hellwig, "Liquid Fuels From Coal by The
H-Coal Process", Mining Congress Journal, 55_, 62-67 (1969).
61. Lee, A. L., H. L. Feldkirchner, F. C. Schora, and J. J. Henry, "Heat
of Reaction of Hydrogen and Coal", Industrial and Engineering
Chemistry, Process Design and Development, l_t 244-249 (1968)7
62. Lindsly, R. R., "Review of U.S. Oil and Gas Production - 1965",
Journal of_ Petroleum Technology, 18, 947-949 (1966).
63. Matsukura, M., and A. Sukakibara, "Hydrogenolysis of Protolignin. IV."
Chemical Abstracts. 73_:26796w (1970).
64. Mullineaux, R. D., and J. D. Raley, "High Temperature Reactions of
Iodine and Hydrocarbons. II. Aroinatization", Journal of The
American Chemical Society, 85, 3178-3180 (1963).
65. Ohta, M., and A. Sakakibara, "H' drogenolysis of Protolignin. III."
Chemical Abstracts. 73_: 267.1? (1970).
66. Orpjiey, R. d., and R. I. Jerman, "Gas Chromatographic Analysis of
Liquid Condensates from The Pyrolysis of Solid Municipal Waste",
Journal of_ Chromatographic Science, £, 672-674 (1970).
67. Pepper, J. M., and Y. W. Lee, "Lignin and Related compounds. I. A
Comparative Study of Catalysts for Lignin Hydrogenolysis",
Canadian Journal of_ Chemistry, 4_7, 723-727 (1969).
68. Peterson, Wm. E., "Hydrogenation ar.a Hydrogenolysis Products From
Bark Phenolic Acids", Master of Science Thesis, Oregon State
University, Corvalli,s Oregon 1964.
69. "Plowshare Closer to Commercialization", Chemical and Engineering News,
£7_, 38-39 (1969).
70. "Project Gasoline in Final Development Stage", Chemical and Engineering
News, 45_, 96-98+ (1967).
71. "Project Rulison; more Hope for Success", Chemical and Engineering
News, 47_, 10-12 (1969).
72. "Pyrolytic Decomposition of Solid Wastes", Public Works. 99(8),
82-83 and 160 (1968).
123
-------
73. Quader, S. A., and G. R. Hill, "Catalytic Hydrocracking; Hydrocracking
of Low Temperature Coal Tar", Industrial and Engineering Chemistry,
Process Design and Development, £, 450-455 (1969) •
74. Quader, S. A., and G. R. Hill, "Catalytic Hydrocracking, Mechanism
of Hydrocracking Low Temperature Tar", Industrial and Engineering
Chemistry, Process Design and Development, 8_, 456-461 (1969)
75. Raley, J. H., R. D. Mullineaux, and C. W. Bittner, "High Temperature
Reactions of Iodine with Hydrocarbons. I. Dehydrogenation",
Journal of_ The American Chemical Society, 85, 3174-3178 (1963).
76. Rieche, A., L. Redinger and K. Lindenhayn, "Hydrogenation of Lignin",
Brenstoffe Chemie, 47 (U), 326-330 (1966).
77. Schlinger, W. G., and D. R. Jessie, "Hydrotorting Oil Shale",
Industrial and Engineering Chemistry, Process Design and
Development. 7_, 275-277 (1968).
78, Schultz, E. B. Jr., and H. R. Linden, "From. Oil Shale to Production
of Pipeline Gas by Hydrogenolysis", Industrial and Engineering
Chemistry, Sl_, 573-576 (1956).
79. Slaugh, L. H., R. D. Mullineaux, and J. H. Raley, "High Temperature
Reactions of Iodine with Hydrocarbons. III. Rearrangement of
Aliphatic Free Radicals", Journal of_ The American Chemical
Society, 85_, 3180-3183 (19637!
80. Storch, H. H., N. Golumbic, and R. B. Anderson. The Fischer-Tropsch
and Related Synthesis, John Wiley and Sons, Inc., New York (1951).
t
81. Struck, R. T., W. E. Clark, C. W. Zielke, and E. Gorin, "Kinetics of
Hydrocracking of Coal Extract Wtih Molten Zinc Chloride Catalyst
in Batch and Continuous Systems", Industrial and Engineering
Chemistry, Process Design and Development, 8_, 546-551 (It/69).
82. Szucs, M., "Hydrogenation of Hungarian Coals in Oil Suspension",
Chemical Abstracts, 50_:6019d (1956).
83. Texaco Development Corporation, "Purification of Hydrogen for Recycle",
French Patent 1,562,026. Chemical Abstracts, 73_:27360m (1970).
84. "U.S. Moves Toward Fuel Crisis", U.S. News, 69_, 26-28 (1970).
85. Van Ling, C., and J. C. Vlungter, "Catalytic Hydrogenation of Saccharides.
II. Formation of Glycerol", Journal of Applied Chemistry, 19, 43-45
(1969).
86. Weinberg, A. M., "Uranium and Coal; Rivals or Partners'1, Mining Engineer,
19, 46-49 (1967).
124
-------
87. Weinberg, A. M., "Uranium, Coal - Rivals or Partners", Mechanical
Engineer, 89, 34-35 (1967).
88. V.'illstatter, R., and L. Kalb, "Uber die Reduktion von Lignin und von
Kohlenhydraten tnit Jodwasserstoffesaure und Phosphor",
Chemische Berichtc, 55_, 2637-2653 (1922).
89. Wolk, R. H., and E. S. Johanson, "Catalytic Fluidized Bed Coal
Hydrogenation", Chemical Abstracts, 73_:37233m (1970).
90. "World Deamnd to Reach 100 Million Barrels Per Day by 1990", World
Oil, 170 61 (1970).
91. "Process Converts Animal Wastes to Oil", Chemical and Engineering
News. 49(33). 43 (1971).
125
-------
"iF^
O\
7
Figiire III. E. 1. Gas Train for Analysis of the Head Gas from the High Pressure Reaction Apparatus.
-------
H
Figure III. E. 2. Carbon Monoxide Analysis System.
Figure III. E. 3. Gas Chromatographic - Mass Spectrometric Analysis System.
127
-------
Table III. E. 1. Reaction Conditions and Products of Hydrogenations
Hydrogenation Statstics
Gaseous Products (Moles/Mole of Cellulose)
Is)
co
Run
23
24
25
26
27
28
29
30
31
'3
o
*3
•— *
*«4
O
100
107.7
92.7
93.7
94.9
93.4
116.2
93.1
93.5
in
tn
rt
1000 H2
950 H2
None
950 H2
850 H2
1000 CO
None
None
None
t— <
in
X
rt
rt
None
25 CH3I
None
None
25 HI
25 1% H2CO.
25 HI
50 H20
None
u
o
1
01
£2
4»
E-
370
355
395
375
350
j 350
370
365
400
4>
oa
o
ti
•o
X
I
1.32
0.085
0.001
2.98
1.41
0.522
0.158
0.0
bon Monoxide
t->
at
CJ
2.42
0.663
0.001
0.332
0.175
1.45
0.219
0.171
bon Dioxide
t->
0)
U
0.398
0.405
0.955
0.750
1.02
0.560
0.595
rocarbons
^O
X
0.208
0.995
1.46
0.526
0.512
0.039
0.329
0.254
-------
Table III. E. 2. Showing the Amounts, in Grains, of Solid
Residue, Oil and Water Produced per Gram of Cellulose Hydrogenated
Run Residue Water Oil
23
24
26
27
28
29
30
0.347
0.341
0.316
0.179
0.318
0.585
0.392
0.157
0.236
0.175
0.374
-
0.069
0.107
'
0.013
0.066
0.135
0.079
0.008
0.016
129
-------
Table III. E. 3. Information Received from Standard Oil
Company Concerning A Sample of Oil
From The Hydrogenation of Waste.
PROPERTIES VOLUME PERCENT
Gravity, "API 31.3
Specific Gravity, 60°F 0.8692
Pounds per Gallon 7.24
Mixed Aniline Point, °F 90
Distillation, D-86, °F
Initial Boiling Point 128 *F
5% Recovered 170
10% " 208
20% " 263
30% " 300
40% " 326
50% " 354
60% " 380
70% " 405
80% " 430
90% " 465
95% "
Dry Point
130
-------
Table III. E. 4. Showing the Crudely Determined
; Material Balance of The Hydrogenation Reactions.
Material Balance
Run
23
25
26
27
28
29
30
c
•H
e
o
rt
U
<4H
0
in
V
_o
3.70
.438
3.46
3.51
, 6.29
4.30
3.44
3
o
e
0
(4
rt
U
•4-t
O
V)
O
1
4.81
.441
3.201
3.32
4.45
4.47
3.67
•H
C
0>
00
s
•a
S
<44
O
%
5.91
3.92
4.66
6.66
4.26
5.36
5.65
o
c
«
t>o
2
•a
X
<«
o
in
V
o
4.19
3.07
6.55
1.71
1.94
3.84
c
•H
c
0
60
fr
0
SH
O
M
V
1
3.08
3.3?
2.8f
4.17
7.11
4.83
5.65
^
0
e:
>j«
o
*w
o
tn
V
1
3.00
2.021
2.201
4.20
2.853
2.26
4.01
131
-------
Etherification
Methyl, ethyl, benzyl, and other ethers of cellulose are important
in the production of textiles, cosmetics, medicines, films, and various
plastic objects. For the product to be technically useful as a p - stic
item, it must regain a certain degree of hardness after being formed by
fluid or plastic flow. Forming depends on applying the right conditions
of temperature and pressure to the cellulose ether, which must have been
formulated to give the desired properties to the product.
Some cellulose ethers may be considered to be, in a sense, internally
plastici'ed by their constituents. The degree of internal plasticizing
appears to be proportional to the size of the substituent group, and is
quite pronounced in the case of the benzyl ether of cellulose. The higher
alkyl ethers appear to have an increasing degree of softness and yet
they exhibit an increasing tensile strength with the increased size of
the substituent group.
The most common of the alkyl ethers of cellulose are ethyl and methyl
cellulose. They are found in plastics, lacquers, sheeting, melts, varnishes,
adhesives, therapeutic eye drops, and cosmetics. As plastics, they are
useful as both soft and rigid plastics because they are tough. They find
uses in both molded and cast objects. Some of the properties of methyl and
ethyl cellulose are shown in Table III. F. 1. While varying degrees of
substitution change the solubility pattern of these compounds, they can
be made insoluble by crosslinking with bifunctional compounds such as:
citric acid, glyoxal, and dimethyl urea.
Chemistry; According to Ni! *in's interpretation (3:328-9) of the
work of several authors. The mono-benzyl ether of cellulose is formed by
treating cellulose with 15-25% sodium hydroxide solution and heating at
1CO°C with benzyl chloride. The use of 40-50% sodium hydroxide will form
the disubstituted product if the reaction is started in a less concentrated
base. This reaction is completed in less than eight hours at 100°C.
At 130°C the reaction takes 2-3 hours.
The benzyl cellulose has a softening point between 145 and 170°C
(293-338°F) depending en the properties of the product. Benzyl cellulose
with a degree of substitution of 2.3 is used for the plastics industry (3:330),
The methyl ether can be made by treating soda cellulose with methyl
chloride or dimethyl sulfate (4). The ethyl ether is made by essentially
the same method (4). For both ethyl chloride, b.p. 12.2°C, and methyl
chloride, b.p. -24°C, an autoclave is necessary to carry out the reaction
without loss of the halide.
Mixed ethers have been prepared (1) by treating soda cellulose with
mixtures of benzyl chloride and diethyl sulfate. The product is suitable
for making filaments and films.
132
-------
Cyanoalkyl cellulose is prepared by treating soda cellulose with
acrylonitrile (2).
Carboxy ethers have been prepared (5) by treatment of soda cellulose
with chloroacetic acid.
Hydroxy alkyl ethers have been prepared (6) from soda cellulose and
ethylene oxide or chlorohydrin. These compounds are used in coatings,
extrusions, and binders for pigments.
Experimental Results: Several samples of the benz>•* ether of cellulose
were prepared by treating soda cellulose with benzyl chloride under
reflux (TM20°C). The soda cellulose was prepared by soaking the cellulose
in 30% sodium hydroxide aqueous solution for 1 hour. Soda cellulose made
from Whatman #40 filter paper was treated with benzyl chloride for 2 hours
to yield an orange product. This orange material was pressed at 300°F,
2000 Ibs/in^ for 4 minutes to form a hard disk without any indication of
extrusion from the mold. A second experiment was conducted with the reaction
time increased to 6 hours. Again the product was orange with an odor of
aromatic compounds. On pressing, this mate-rial formed a yellow-brown
translucent disk.
Straw was treated to form the benzyl ether by the same method. The
reaction time was four hours. The product was pressed at 32SCF for 4
minutes at 2000 Ibs/in2 to form a hard fibrous disk. From 10 grams of straw
only 6 grams of product were recovered. The product from a second run
using straw, when pressed at 325°F for 2 minutes at 1000 Ibs/in^, tended
to extrude from the mold. Straw fibers were visible in this plastic.
A sample of sulfuric acid lignin was treated with sodium hydroxide
followed by benzyl chloride in the same manner as noted earlier. When
pressed, the product was bonded but did not flow. Fibrous particles were
seen in this material also.
A sample of glucose was treated in the same manner. The product was
a yellow liquid which would not crystallize.
Discussion; Several cellulose ethers are used commercially at present.
If these are used for plastic molding or casting purposes there is reason
'to believe that the purity of the cellulose source does not have to be
exceedingly high for many of these products.
Pure cellulose, in the form of filter paper, appears to give a product
in which the plastic properties can be controlled more easily than with
the impure straw. The benzyl ethers of sugars in the straw are thought to be
the cause of the increased plasticity and flow properties of the second run.
When glucose was treated, the benzyl ether was recovered as a yellow
oily substance which would not readily crystallize. Such a material could
easily act as a plasticizer.
133
-------
References
1. Dreyfus, H., "Benzyl-ethyl Cellulose Ethers," Chemical Abstracts,
17:2505' (1923).
2. Hutchinson, W. M., "Carboxycellulose Ethers," Chemical Abstracts,
4£:10319a (1950).
3, Nikitin, N. I., The Chemistry of Cellulose and Wood, Isreal Program
for Scientific Translations, Jerusalem 1966.
4. Ott, E., H. M. Spurlin, and M. W. GraffHn, "Cellulose and Cellulose
Derivatives", Volume 5, Hi^h Polymer Series, 2nd edition,
Interscience Publishers, Inc., New York 1954.
5. Waldeck, W. F., "Carboxymethyl Cellulose", Chemical Abstracts,
44_:7538f (1950).
6. Ward, K., Jr., A. J. Morak, R. H. Giliespie, and M. H. Voelker,
"Hydroxyethylation of Linters Pulps. II. Effect of Alkali
Concentration," The Journal of The Technical Association of
The Pulp and Paper IndustrieVTTappi)", 51(5), 2T8-Hi (19687.
134
-------
Table III. F. 1. Some Properties of the Methyl
and Ethyl Ethers of Cellulose.
Ethyl
Degree of substitution Property
2.60-2.8 Soluble in hydrocarbons
2.20-2.58 Thermoplastic; soluble in common
organic solvents
.8-1.7 H20 soluble; difficult to control
Methyl
2.4-2.8 soluble in polar organic solvents
1.6-2.0 soluble in cold H20
.1- .9 soluble in 4-10% of NaOH
Made insoluble with crosslink by bifunctional compounds.
135
-------
Oxidation of_ Cellulose
Because of the similarity, in respect to chemistry, between dialdehyde
cellulose (DAC) and dialdehyde starch (DAS), derivitives of dialdehyde
starch have been included in this report. One finds upon examination of
the literature that most of the derivitive preparation has been done with
DAS, but structural examinations through infrared spectroscopy have been
carried out on DAC. DAC and DAS seem to undergo all of the reactions
typical of aldehydes. DAS is commercially prepared by The Miles Chemical
Works using an electrolytic production of periodate.
Several reactions of dialdehyde polysaccharides (DAP) with nitrogen
compounds have been studied. Kuznetsova et al. (23) reacted DAC in aqueous
solutions at room temperature during 24 hours, or at the boiling point of
the mixture in 4 minutes, to give a series of amino compounds. Thermal
stability varied, but generally decreased in the following order:
m - p - 0;2N)2C6H4 > N2H4 > o - (NHp2 C^
The stricture of the products was determined to be
tyHR
C
X°\c_0/
CH2OH
la
Roqovin et al. (35) reacted DAC with aromatic amines to synthesize Schiff-Type
bases (Ic above) which were useful in preparation of chemically colored
cellulose fibers from various diazo compounds. A patent (39) exists
for the condensation of o-aminophenol with a dialdehyde. This type of
compound is useful as tuberculostats and intermediates for the preparation of
medicines and dyes.
Patents exist on the reactions of DAP with melamine and other triazines.
The uses so far have been in papermaking. These reactions impart wet
strength and dimensional stability to paper.
Honeyman end Holker (18) reacted DAC with several amines and hydrazine
derivatives, but reported the reaction to be incomplete in all cases.
The products remained alkali sensitive making them of no value to the textile
industry. Material treated with urea was wrinkle and flame resistant, while
the thiosemicarbazide is resistant to attack by most fungi.
DAC undergoes reaccion with the hydrazides. With phenylhydrazine a
phenylformazan, He, is formed showing that the DAC reacted to give one
of the two possible hemi acetals, Ha and lib, (28).
136
-------
Q'2
A°\
/ o V ^ _ ^
J / ^ ^
C-J HC •
OH 0 / •
OH ° ' 0 OH OH N-NHph
Ha lib He
Hemi-acetal forms formazan
DAS has been left standing in liquid ammonia to produce a compound
containing two nitrogen atoms per dialdehyde unit (40) . The product decomposed
on standing, because of the unstable nature of the a-amino alcohol, Ilia,
formed. It is possible for the reaction
RCH(OH)NH2 "H2°fc.. R - CH = Nil
Ilia Illb
to occur. From I lib one can obtain I He.
Illb
3R - CH = NH
The dioxime of DAC is readily formed. Reduction of the dioxime gives
the aiaine, while dehydration gives the nitrile. A literature search has
not revealed the formation of the nitrile from DAC using the cyanide ion.
Rogovin (36) states that the diamino derivatives, from the reduction
of the oxime, can be used to initiate grafting of monomers, particularly of
the cyclic type.
DAP acetals have been produced and are used in coating and laminating
applications. DAP-phenol derivatives (29) are used in resins and adhesives.
Several patents (2, 3, S, 22) cover the production of dialdehyde polysaccharide-
urea resin. These products have applications as adhesives, wet strength
agents for paper, and textile finishing agents. The resin formed is
a thermo-setting resin. A casein-DAS resin has been prepared and tested
for use as a plywood bonding agent (42).
137
-------
A general reaction of aldehydes with epoxides (40) might be found to
be useful, since a patent covering aldehyde-epoxide copolymers formation •> '
using poly(hydrocarbyl aluminum) catalyst does e
-------
The C02 yield and increased weight loss noted with increasing
degree of oxidation are considerably greater for periodic acid than for
metaperiodate oxidations (7). Periods of a week or more are necessary
for production of a high degree of oxidation in cellulose. Acid
hydrolysis does not play an important part in the oxidation of cellulose
by periodic acid. The possibility of acid attack during the metaperiodate
oxidation is ruled out by the low hydrogen ion concentration in the
raetaperiodate solutions.
The properties of dialdehyde cellulose are markedly different from
those of cellulose, for instance the strength of the dialdehyde cellulose
is slightly lower than that of cellulose. Periodic acid oxidized
cellulose shows an increased hygroscopicity over that found in cellulose.
Treatment of cellulose sheets with periodic acid results in pronounced
shrinkage in area, but increased thickness. The introduction of two
aldehyde groups into the anhydroglucose unit of cellulose produces
considerable decrease in stability of the glucosidic bond to the action
of alkali. All of these differences are brought about because the
periodate ion can penetrate the ordered as well as the disordered areas
of cellulose to produce the dialdehyde cellulose. The production of
periodate oxidized cellulose can be found in references 14, 15 and 43.
Preparation of metaperiodate solution is accomplished by adding
sodium hydroxide to periodic acid in the proportion of one mole of
base to one mole of acid, or by dissolving recrystallazed salt in
distilled water. The final solution used in the oxidation of cellulose
to dialdehyde cellulose is usually 0.1 Molar in metaperiodate.
Lead Lead tetraacetate in glacial acetic acid oxidized glycols
Tetraacetate to pairs of carbonyl groups at rates which were greater
for cis than trans configurations and were dependant upon the particular
glycol.
Detrick (9) made a thorough study of the oxidation of wood pulps
by Pb(OAc)4 and found that there was a selective oxidation of mannose
units. In addition, a smaller but significant removal of xylose units
occurs. In his oxidation of pulp, Detrick treated dry pulp with acetic
acid at 50°C to activate the pulp. Preheated lead tetraacetate in
glacial acetic acid was then added and the reaction allowed to proceed.
Ten hours was found to be about the minimum reaction time. The reaction
was quenched using a solution of potassium iodide, and sodiun acetate
in distilled water. Quenching can also be accomplished using oxalic acid.
The type of pulp used, affects the length of time needed to reach a
certain level of oxidation. A minimum of about seven hours is required to
reach 0.2 atoms of oxygen consumed per anhydroglucose unit.
Abdel-Akher (1) oxidized various polysaccharides using a lead tetraacetate
and sodium acetate solution. The reaction Mixture was kept in the dark
at 25°C for 15 - 45 days with an occasional shaking and addition of
lead acetate. The insoluble residue was removed by centrifugation,
Vashed with acetic acid, water, ethanol, acetone, and ethyl ether, then
139
-------
dried in vacu to give 88 - 95% partially oxidized polysaccharide. With
cellulose he achieved 17.21% dialdehyde units.
Vargha (41) states that red lead, Pb304, can be used in many cases
to replace lead tetraacetate.
Peroxydisulfate Heidt (16), in a review article of the oxidation
of cellulose to dialdehyde cellulose, indicates four possible oxidants:
periodate, lead tetraacetate, peroxydisulfate, and perbismuthate. At
the time of the article (1945) no work had been reported using peroxy-
disulfate. A review of the literature by Menghani (27) in 1969 indicated
that the oxidation of diols by persulfate had not been reported. A
literature search has not turned up any reported work since that time.
Rusznak, Kantouch, and Khalil (38) studied the oxidation of
cellulose with sodium persulfate at 50-70°C, pH 4 - 10, and with solutions
of persulfate ranging in strength from 0.05 - 0.3 N. The oxygen consumed
(determined by titration with acidic ferrous sulfate) in the oxidation
increased with increasing time, pH, temperature, and persulfate concentration.
At pH 8 and 70°C, oxygen was released faster than the rate of oxidation
of cellulose with a subsequent evolution of oxygen.
Work done by Menghani (27) indicates that in the oxidation of
ethanediol using persulfate with silver ion as catalyst, the rate of
persulfate disappearance depends on both the persulfate and silver ion
concentrations.
Oxygen causes an inhibition period with peroxydisulfate which is
dependant on the amount of dissolved oxygen present.
Perbismuthate Perbismuthate is a rapid acting oxidizing agent, but there
is a drawback to its use with cellulose: Perbismuthate is a relatively
insoluble brown powder, whose reduced form Bi(OH)3 is also poorly
soluble. These properties render perbismuthate cf little value for use
in oxidizing cellulose or other insoluble substances (16).
Chromic Acid and The early stages of the oxidation of cellulose by
Chromic Anhydride chromic acid produces dialdehyde cellulose.
Cotton oxidized by chromic acid falls into a powder when the oxygen
consumption reaches about 0.4 atoms per anhydroglucose unit (8). Chromic
acid oxidation does not lead to marked swelling as does the periodate
oxidation. Chromic acid confines its attack to the disordered regions of
the cellulose fiber. It also leads to an increase in hygroscopic ity
which is not as high as in the periodic acid oxidations. Both chromic
acid oxidized and periodate oxidized cellulose show a decrease in tensile
strength, but in the latter stages of oxidation the chromic oxidized
cellulose has a much lower tensile strength (32).
140
-------
Feher (10) proposed an industrial application of electrolytic
oxidation with chromic acid of starch using the method of Mehltratter
and Wise (26), but found the method inconvenient. He then proposed
the use of potassium dichromate in strongly acid medium. The product
contained 60% dialdehyde and only 4-5% -COOH groups.
Gladding and Purves (13) did an extensive study on the use of
chromic anhydride dissolved in acetic acid-acetic anhydride, and in
sulfuric acid, on cellulose. The acetic acid solvent was found to be
more efficient in producing carbonyls and about 10 times faster than sulfuric
acid solution.
t-Butyl Oxycelluloses containing aldehyde groups in the C-6
Chrpmate position are prepared from cellulose or partially
substituted cellulose, at 20 - 70°C, in an acetic anhydride solution of
of t-butyl chromate (37). The fibrous products are white and stable
when stored in the absence of light and oxygen. They are useful for
surface coatings and finishes on textiles through cross-linking reactions.
Hypobromite Oxidation of cotton by hypobromite in concentrated alkaline
hypobromite solutions is non-selective and approaches wet conbustion (11).
Hypochlorite In alkaline solutions, where the effective oxidant is the
hypochlorite ion, the reaction is very slow and gives rise to an acidic
oxycellulose with little reducing power (43). In mildly acidic solution,
pH 3 - 5, in which the effective oxidant is undissociated hypochlorous
acid, the reaction is again slow but gives rise to a highly reducing
oxycellulose containing fe* acidic groups. In neutral solutions the
rate of reaction is at its maximum, and oxycelluloses with both acidic
and reducing properties are produced.
Hydrogen Oxidation by hydrogen peroxide is essentially the same
Peroxide as hypochlorite, but during the oxidation of cellulose
the glycol grouping at C-2 and C-3 are attacked simultaneously, resulting
in the formation of two aldehyde groups (43).
Nitrogen Nitrogen dioxide is a more or less specific reagent which
Dioxide oxidizes primary hydroxyl groups in cellulose to carboxyl
groups (31). Cellulose may be oxidized by gaseous nitrogen dioxide,
by the liquid tetroxide, or by solutions of nitrogen tetroxide in inert
solvents.
Chlorine Chlorine dioxide, in acid medium, does not react with
Dioxide cellulose (31), however in any other media it leads to
oxidation of aldehyde groups to carboxyl groups. This oxidation involves
both the terminal hemiacetal groups and aldehyde groups formed by the
oxidation of cellulose by other oxidizing agents.
Experiment. •.esults: There are several oxidative materials that
may be used to },.oduce dialdehyde cellulose. For several reasons, we
elected to work with periodate, chromic acid, and persulfate oxidations
first. Periodate oxidations are well documented and there is little
doubt that it is fairly specific for vicinal hydroxyl cleavages. Nikitin
141
-------
(31) does note however, that about 10% of the primary (C-6) hydroxyls
are oxidized during the reaction.
Basically, there are two ways of determining the degree of oxidation
of the sample: by measuring the fall in the concentration of the oxidative
material, or by reacting the carbonyl units in the product with a reagent
that is specific for such groups. Neither method appears ;o be
exceedingly accurate. The decrease in oxidative agent does not mean
that only the aldehyde is formed nor are many aldehyde specific reagents
completely reacted because of the stereochemistry of the cellulose.
Hydrolysis of the cellulose to glucose units would obviously lead to
higher yields of oxime because of additional aldehyde units available.
Chromic acid oxidation is not as selective as the periodate method,
but a comparison was run using the method of Whistlor (43).
A comparison of our kinetics and those of Whistler was made.
Whistlers method was modified by buffering to pH = 5 by the addition of
acetic acid and sodium acetate for use with samples 1 and 2. A large
discrepancy was found between the oxygen consumption and the amount of
carbonyl present by oxime formation for samples 1 and 2, Table III. G. 1.
An interesting phenomenon is the apparent increase in periodate concentration
in the first two days. This work was not repeated to confirm this observation.
The large amount of hydroxylamine consumed in oxime format vn ?or
samples 1 and 2 indicates oxidation of the C-6 carbon probably took place.
Table III. G. 2. contains the results of the persulfate oxidation
experiments. Ammonium persulfate was used as the oxidizing agent, and
the reaction times ranged from 15 minutes to two days using various catalysts.
The most noticable change was the loss of weight of the cellulose.
Oxime analysis indicates few carbonyl groups were formed. The pH was
maintained at 2 except when a buffer was added. At a pH of 2 one
would expect hydrolysis of the cellulose to glucose which probably
accounts for some of the weight loss.
The chromic acid hydrolysis was carried out using the method of
Whistler (43). Figure III. G. 1. shows the oxygen consumption versus
the reaction time. Table III. G. 3. gives the data from this work,
comparing the titrametric (oxygen consumption) analysis with the analysis
by oxime formation. One can readily see that the data indicates carboxy
unit formation rather than carbonyl formation.
Alkaline degradation of the oxidized cellulose was observed
when the pH was allowed to become too high during oxime formation.
Discussion: There are a number of oxidizing agents capable of
converting cellulose to dialdehyde cellulose (DAC) or carboxyl cellulose.
At present there are not enough uses known for this substance to justify
spending much time examining this process.
142
-------
The conversion of cellulose to DAC has many interesting possibilities
if the reaction rate could be increased to make the process economically
feasible. DAC, made from waste paper, could possibly be used as the
basis for resins for water purification, for resins to be used by the
plastics industry, paint industry, and many other applications.
Because of the long periods of time needed for the formation of
DAC, this material was only briefly examined in this laboratory.
Cellulose peroxides were not examined, but hold a special interest
because of their potential use as initiators for graft polymerization.
In general the formation of DAC was found to be better with the
periodates, as the literature suggested, than with other oxidizing agents.
However at present this does not look like an economically feasible
method for handling the large quantities of wastes necessary for the
solution of the problems of pollution in this country.
143
-------
References
1. Abdel-Akher, M., "Oxidation of Polysaccharides with Lead Tetraacetate",
Journal of Chemistry UAR, 6(1), 107-118 (1963). Chemical Abstracts,
63_:7090g (1965).
2. Borchert, P. J., "Preparation of Urea-Dialdehyde Starch Derivatives",
U.S. Patent 3,001,979 (September 26, 1961) (Miles Laboratories).
Institute of Paper Chemistry Abstract Bulletin, 32_:41S5 (1962).
3. Borchert, P. J., "Dialdehyde Polysaccharide-Urea Resin Dispersions",
Canadian Patent 691,461 (July 28, 1962) (Miles Laboratories).
Institute of_ Paper Chemistry Abstract Bulletin, 35;. 3801 (1965).
4. Borchert, P. J., "Dialdehyde Polysaccharide-Acrylamide Derivatives",
U.S. Patent 3,100,203 (August 6, 1963) (Miles Laboratories).
Institute of_ Paper Chemistry Abstract Bulletin, 34:9112 (1964).
5. Borchert, P. J., ''Dialdehyde Polysaccharide-Urea Derivatives",
U.S. Patent 3,177,250 (April 6, 1965) (Miles Laboratories).
Institute of Paper Chemistry Abstract Bulletin, 36_:1971 (1965).
6. Cremonesi, P., and L. D'Angiuro, "Graft Copolymerization of Methyl
Methacrylate on Cellulose Initiated by Catalytic Decomposition
of Cellulose Peroxides", Cellulose Chemistry ami Technology,
3(6). 599-611 (1969). Institute of Paper Chemistry Abstract
Bulletin, 4Jjl933 (1970).
7. Davidson, G. F., "The Progressive Oxidation of Cotton Cellulose by
Periodic Acid and Metaperiodate Over a Wide Range of Oxygen
Consumption", Journal of The Textile Institute, 32, T109-T131
(1941).
8. Davidson, G. F., "The Progressive Oxidation of Cotton Cellulose by
Chromic Acid Over a Wide Range of Oxygen Consumption",
Journal of_ The Textile Institute, 32_, T132-T148 (1941).
9. Detrick R. W., "The Oxidation of ICCA Pulps With Lead Tetraacetate",
The Journal of_ The Technical Association of The Pulp and Paper
ImTustrTlTappi), 45(7), 654-638 (1960).
10. Feher, I., "Oxidation of Starch to Dialdehyde Starch", Bor-es
Cipotech, 11(21. 33-36 (1961). Chemical Abstracts, 55_:25305a
(1961).
11. Fossen, P. V., and E. Pacsu, "Cellulose Studies. III. Hyperoxidation
of Cellulose with Concentrated Sodium Hypobromite Solutions.
A Simple Method for The Determination of Hypobromite and Bromate
Ions in The Presence of Each Other", Textile Research Journal,
16, 163-170 (1946).
144
-------
12. Frostick, F. C. Jr., and B. Phillips, "Resins From 1,2:5,6
Diepoxycyclooctane", U.S. Patent 3,065,209 (November 20, 1962).
Chemical Abstracts, 5£:P10357b (1963).
13. Gladding, E. K., and C. B. Purves, "Estimation of Carbonyl Groups
in Chromic Anhydride Oxystarch and Oxycellulose by Means of
Hydroxylami-ne", Paper Traded Journal, 116(4), 26-31 (1943).
14. Guthrie, R. D., "The Dialdehyde from Periodate Oxidation of Carbohydrates",
Volume 16, pp. 105-157, Advances in Carbohydrate Chemistry,
Academic Press, New York, 1961.
15. Head, F. S. H., "Effect of Light on The Reaction Between Periodates
and a-glycols", Nature, 165, 236-237 (1950).
16. Heidt, L. J., E. K.Gladding, and C. B. Purves, "Oxidants That Promote
The Dialdehyde Cleavage of Glycols, Starch, and Cellulose",
Paper Trade Journal, 121(9), 35-43 (1945).
17. Hobart, S. R., C. H. Mack, and C. P. Wade, "The Wrinkle Recovery
Properties cf Acethyhrazide Disulfide Crosslinked Dialdehyde
and Dialcohol Cottons", Textile Research Journal, 36(1),
30-27 (1966).
18. Honeyman, J., and J. R. Holker, "Some Derivatives of Periodate
Oxycellulose", Textile Rundshau, 16, 561-570 (1961).
Chemical Abstracts, S6_:5000h (1962).
19. Ide, F., and M. Nakatsukak, "Graft Copolymerization of Dialdehyde
Starch", Chemistry of Hi.gh^ Polymers (Tokyo) (Kobunshi Kagaku),
21(225), 49-56 (19647. Institute of_ Paper Chemistry^AbstracY
Bulletin, 3S_:1800 (1964).
20. Imperial Chemical Industries Ltd., "Bis(amidinohydrazones)",
British Patent 819,587 (September 9, 1959). Chemical
Abstracts, S4_:P3513c (1960).
21. Imperial Chemical Indsutries, Ltd., "Cellulose Derivatives",
British Patent 1,081,732 (August 31, 1967). Chemical
Abstracts, 67;P110241v (1967).
22. Kuznetsova, N. Y., G. A. Timokhiva, and V. I. Ivanov, "Amino
Derivatives of Cellulose", U.S.S.R. Patent 203,665 (October 9,
1967). Chemical Abstracts, 68_:96946r (1968).
23. Kuznetsova-Lenshiva, N., G. A. Timokhiva, N. Zhavoronkov, and V. I.
Ivanov, "Synthesis and Structure of Some Nitrogen Containing
Derivatives of Dialdehyde Cellulose", Chemical Abstracts,
70:5300c (1969).
24. Livshits, R. M., and I. A. Rogovin, "Synthesis of Graft Copolymers
Using Pentavalent Vanadium", Institute of Paper Chemistry
Abstract Bulletin, 33:1801 (196271
145
-------
25. Marvel, C. S., and II. W. Hill, Jr., "Polyazines", Journal of The
American Chemical Society, 72_, 4819-4820 (1950).
26. Mehltratter, C. L., and C- S. Wise, "An Electrolytic Process for
Making Sodium Periodate", Industrial and Engineering Chemistry,
5JU 511-514 (1959).
27. Mehghani, G. D., and G. V. Bakore, "Kinetics of Oxidation of Ethanediol
by Peroxydisulfate Catalyzed by Silver Ions", Zeitschrift fur
Physikalische Chemie, 241(3-4), 153-159, (1969).
28. Mester, L., "The Formazan Reaction in Proving The Structure of Periodate
Oxidized Polysaccharides", Journal of_ The American Chemical
Society, 7T/.5452-5455 (1955).
29. Miles Laboratories Inc., "Dialdehyde Polysaccharide-Phenol Derivatives",
British Patent 932,657 (July 31, 1963) Institute of Paper
Chemistry Abstract Bulletin, 34_: 7367 (1964).
30. Muratora, U. M., A. Yuldashev, R. V. Perlina, M. I. Ismailova, and
Kh. U. Usmanov, "Reaction of Dialdehyde Cellulose with
Trialkyl Phosphites", Institute of Paper Chemistry Abstract
Bulletin, 4£:8673 (197077^
31. Nikitin, N. I., The Chemistry of Cellulose and Wood, pp. 155-179,
Israel Program for Scientific Translations Ltd., Jerusalem,
1966.
32. Ott, E., and H. M. Spurlin, Volume V, Part 1, pp. 165-167,
Cellulose and Cellulose Derivatives, Interscience Publishers
Inc., New York, 1954.
33. Puzyrev, S. A., E. Ya. Pechko, B. B. Gutman, and A. E. Gushchin,
"Oil and Oil Filters", Chemical Abstracts, 66_:48154t (1967).
34. Roches, P., and G. Edel, "The Action of Semicarbazide and of
Thiosemicarbazide on Cellulose Oxidized With Periodic Acid",
Institute of_ Paper Chemistry Abstract Bulletin, 33:1806 (1962).
35. Rogovin, Z. A., N. A. Yashunskaya, and V. Bcgslovski, "Preparation
of Chemically Dyed Fiber", Chemical Abstracts, 46_:4235g (1952).
36. Rogovin, Z. A., L. S. Galbraikh, and A. I. Polakov, Encyclopedia
of_ Polymer Scicr :o and Technology, 3_, 291-306 (1964).
37. Roth, C. B., "Oxycelluloses", U.S. Patent 2,758,111 (August 7, 1956).
Chemical Abstracts, 51:713g (1957).
146
-------
38. Rusznak, I., A. Kantouch, and M. Khalil, "Reaction of Cellulose
and Peroxydisulfates", Kolpr Ert, 10(1-2), 38-49 (1968).
Chemical Abstracts, 68;96724s (1968).
39. Schafer, W., R. Wegler, and Domagk, "Anils of Dialdehydes",
(Farbenfabriken Bayer Akt-Ges.)> German Patent 1,007,729
(May 9, 1957). Chemical Abstracts, 5£:21812b (1959).
40. Sloan, J. W., B. T. Hofreiter, R. L. Mellies, and I. A. Wolff,
"Properties of Periodate Oxidized Starch", Industrial and
Engineering Chemistry, 48(7), 1165-1172 (1956).
41. Vargha, L., "Red Lead as a Selective Oxidant", Nature, 162,
927-928 (1948).
42. Weakly, F. P., M. L. Ashby, and C. L. Mehltratter, "Casein-
Dialdehyde Starch Adhesives for Wood", Forest Products
Journal, 15(2), 51-55 (1963).
43. Whistler, R. L. (editor) "Cellulose", pp. 164-180, Volume III,
Methods Iii Carbohydrate Chemistry, Academic Press, New York,
1963.
44. Yashungkaya, A. G., N. N. Shorygina, and Z. A. Rogovin, "Preparation
of Dialdehyde Cellulose and Its Esters", Chemical Abstracts,
44_:835i (1950).
45. Zenftman, H., and D. Calder, "Difluoraminated Dialdehyde Cellulose
and Nitric Acid Esters Thereof", U.S. Patent 3,426,013
(February 4, 1969). Institute of_ Paper Chemistry Abstract
Bulletin, 39:9853 (1969).
147
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140
in
8 120
1-4
tie
o
o
i
*j
0)
C
oo
g
I
s
oo
100
80
60
40
20
1 2345
Time (days')
Figure III. G. 1. Showing The Oxygen Consumption With Time in The Chromic
Acid Oxidation of Filter Paper.
148
-------
Table III. G. 1. Periodate Oxidation
Sample I lOg filter paper; 1 N NaI04; 1 liter of soln; 2/7/72-2/17/72
20 mis of HOAc-NaOAc buffer pH 4.
Days 123456789 10
Oxygen
Consumption 1.8 6.9 11.1 - - 21.4 - 24.7 25.7
% Conversion
(Oxime) >100%
Sample II 20g paper; 5 N NaK>4; 1 liter of soln; 2/7/72-2/17/72
20 nls of HOAc-NaOAc buffer pH 4.
Days 1 23456789 10
Oxygen
Consumption .9 2.6 - 7.8 - 9.9 10.8
% Conversion
(Oxime) >100%
i
Sample III 20g paper; S N NaI04; 1 liter of soln; 2/8/72-2/21/72
no buffer
Days 1 2 3 4 S 6 7 8 9 10 11 12 13
Oxygen
Consumption 2.9 5.0 6.4 - - 9.2 - 10.6 11.2 13.2
% Conversion
(Oxime) 77%
149
-------
Time (min)
Table III. G. 2. Persulfate Oxidation
pH Catalyst % Conversion Weight Loss (gm)
20
30
60
120
2 days
120 min
120 nin
15
30
2
2
2
2
2
2
2
4
4
Ag
Ag
Ag
Ag
Ag
Fe*
_
Ag+
AE*
0
0
0
6.2
0
0
0
0
0
0
0
.3
.1
.33
0
0
0
Days
Table III. G. 3. Chromic Acid Oxidation
lOg paper: 30gm Na2Cr207 5 11 mis cone. H2S04 per liter; 2/4/72-2/9/72
1234
Oxygen
Consumption
% Conversion
(Oxime)
- 92.6 136.8
15
150
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Pulping of_ Straw
For many years straw was pulped in this country, and in other countries
it is still pulped. Why is straw no longer used for pulp in this country?
Some sources say that the straw pulp mills would not modernize, while this
did not impair the quality of the product, tha cost per unit of product was
forced upward until these mills priced themselves out of existence. Others
say that straw storage is too much of a problem.
With our forests being depleted the time has come to re-evaluate straw
and waste paper as a source of pulp. If this pulp is unsatisfactory for
paper it may still be satisfactory for cardboard cartons, chemical inter-
mediates, or wrapping paper.
The Institute of Paper Chemistry (9) has compiled a bibliography listing
articles and books covering cereal straws as a source of cellulose for paper-
making. The original publication has been supplemented twice (7) i8). These
articles are primarily concerned with papermaking and not with growing,
harvesting, economics, or extraction of the straw.
Straw can be pulped by nearly any pulping process, however, these are not
necessarily economical. The high silica content of straw can cause problems
in boilers, while the low bulk density can reduce equipment capacity.
Straw lignins can be removed from the cellulose by nitric acid pulping
or by the soda process. Laboratory evaluation has shown that both of these
methods are effective in producing pulp from grass seed straws. A third
method, holopulping (5), which is supposed to have less pollution than the
Kraft process has not been investigated yet.
Chemistry: Th- re are several methods available for pulping cellulosic
materials, among these are the sulfite process, the sulfate (Kraft) process,
soda process, nitric acid process and the holocellulose process.
Nitric Acid The nitric acid pulping process (1), (2), (3), (4) consists
Pulping of treating straw with hot nitric acid to oxidize and nitrate
the lignin. The lignin is then dissolved by a dilute sodium hydroxide solu-
tion.
In the laboratory bentgrass and fescue straw treated with 10% nitric acid
at 70°C for 1 hour followed by a 2% sodium hydroxide treatment for 1 hour at
90°C resulted in 29% and 30% pulp respectively. Three similar runs with
annual ryegrass resulted in an average yield of 26%. Because less concen-
trated acid should result in less degradation, a series of runs were made to
determine the effect of nitric acid on the pulp yield. The alpha cellulose
content of the pulp from each run was measured. These results are shown in
Table III. H. 1., and Figure III. H. 1. As expected, the pulp yield increased
with decreased acid concentration.
151
-------
Linear extrapolation to zero nitric acid concentration indicates that
sodium hydroxide alone should result in a 41.5% yield of pulp with 83.5% alpha
cellulose.
Sodium In a series of runs straw was pulped in IN, 3N, and 6N sodium
Hydroxide hydroxide at 70°C for 1 hour. The resulting pulp yields were
Pulping 38.5, 38.2 and 35.7% respectively. Another sample was treated
with IN sodium hydroxide for 2.5 hours at 70°C. The pulp yields for all runs
are shown in Table III. H. 2. The 6N sodium hydroxide treated straw became
gummy and hard to handle.
The Forest Research Laboratory of The School of Forestry at Oregon State
University then did some additional work with straw using the "Soda Process"
(4). They reported yields between 50% and 60% using 16% (4N) chemical. The
tensile, burst, and fold strengths compared favorably with the commercial
soft wood Kraft papers.
Discussion! As stated earlier, pulping can be accomplished by the use
of one of several methods. The "soda process" has been shown to be satisfactory
for making pulp from straw. Because the use of sulfur compounds has been
eliminated there is practically no smell to mills using the soda process.
The holopulping process which was not examined in this laboratory reportedly
(5) is more economical than the Kraft process.
The main drawbacks to using straw are all expressed in economic terms. The
information from pulping of grass seed straws is minimal. More work in this
area, improved techniques for handling and storing straw, and the dwindling
forests may soon bring straw back into the field of pulp production.
152
-------
References
1. Brink, D, L., "Pulping Process Studies. I. Aspects of an Integrated
Nitric Acid Pulping Process," Journal of The Association of
Pulp and Paper Industry, 44(4). 256-262~7l96l") •
2. Brink, D. L.; Vlamis, J.; and Merriman, M. M., "Pulping Process Studies.
II.", Journal of The Association of Pulp and Paper Industry. 44(4)
263-270 (1961)
3. Brink, D. L.; Merriman, M. M.; and Schwerdtfeger, E. J., "Pulping
Process Studies. III." Journal of the Association of Pulp
and Paper Industries, 4Jj](457~315-326~Tl9625
4. Bublitz, W. J., "Pulping Characteristics of Oregon Seed Grass Residues.
I." Journal of The Association of Pulp and Paper Industries, 53(12),
2291-2294 (1970):
5. "Holopulping to Cost Chemicals Market," Chemical and Engineering News,
47(21), 30-32 (May 19, 1969).
6. Kalisch, John H., "Nitric Acid Pulping. A New Rapid-Cycle Process,"
Journal of_ The Association of Pulp and Paper Industry, SO(12),
44A-51A (19675".
7. Roth, L., and Weiner, J. Papermaking Materials, I_. Cereal Straws, The
Institute of Paper Chemistry, Appleton, Wisconsin, Bibliographic
Series, Number 171, Supplement 1 1963.
8. Roth, L. and Weiner, J. Papermaking Materials. I_. Cereal Straws, The
Institute of Paper Chemistry, Appleton, Wisconsin, Bibliographic
Series, Number 171, Supplement II 1968.
9. West, C. J., Papermaking Materials. JL Cereal Straws, The Institute of
Paper Chemistry, Appleton, Wisconsin Bibliographic Series, Number
171 (1949)
153
-------
45
40
4)
•H
(X
r-4
3
35
30
25
4 6
Nitric Acid (%)
10
Figure III. H. 1. Showing The Reduced Yield with Increased Acid
Concentration During Nitric Acid Pulping.
154
-------
Table III. H. 1. NITRIC ACID PULPING OF ANNUAL RYEGRASS STRAW
Run A B C D
Wt. Dry straw, gms.
Concentration HN03, wt. %
Reaction time at 80°C, hrs.
Concentration NaOH, wt. %
Dissolving time at 90°C, hrs.
Wt. Pulp, gms.
Pulp yield, dry basis, %
Alpha cellulose, %
Beta cellulose, %
Alpha cellulose yield, %
Table III. H. 2
NaOH
Run Cone. (N)
1 1
2 3
3 6
4 3
100.0 100
7.5 4
1 1
2.0 2
1 1
31.5 35
31.5 35
85.5 84
10.4 9
26.9 30
Sodium Hydroxide
Cooking
Time (hr.)
1
1
1
2.5
.0 100.0 100.0
.8 3.8 2.9
1 1
.0 2.0 2.0
1 1
.9 36.8 37.3
.9 36.8 37.3
.5 84.7 84.5
.4 7.6 8.1
.3 31.2 31.5
Pulping of Straw
Cellulose
yield (wt. %)
38.5
38.2
35.7
42.5
100.0
1.9
1
2.0
1
39.2
39.2
84.0
8.0
32.9
155
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PILOT PLANT STUDIES
Economic and Engineering Analysis
Each year industry produces thousands of products which are useful in
society, but when they lose their usefulness they become solid waste, which
must be transported to a disposal site. In the the early years of our
•country, when the population was sparce, it was easy to find disposal
sites. Today serious waste disposal problems exist because disposal sites
are no longer readily available and the amount of waste is increasing be-
cause of our increased population and our convenience packaging of consumer
goods. Improper disposal methods have contributed to environmental pollution.
It is essential that we develop and utilize acceptable waste management
systems.
One alternative to the present method of burial and burning is
reutilization of our wastes. A large portion of our wastes should be
treated as raw materials for the production of new, usable products. Using
solid wastes as raw materials would conserve our natural resources, and at
the same time reduce the amount of waste that needs disposal.
Although the main economic factors of the reutilization processes
are the Capital Investment and The Total Product Cost, other economic factors
to be considered when waste is involved include: resource conservation,
social resistance to change, industry survival, and environmental pollution.
These factors will be discussed in relation to a process designed to use
waste straw to make a solid particleboard through isocyanate crosslinking.
Crosslinking: Straw, the hollow stalks or stems of some agricultural
crops, is a solid waste of agriculture; more specifically, in Oregon,
straw is a solid waste of the grass seed and cereal industries. When
the grass seed or cereal grains are harvested, the straw is normally
left in the field. When the straw is not subsequently removed, a reduction
in crop yields usually occurs the subsequent year. Straw can be removed
by bailing or by tilling (plowing under) with two exceptions; perennial
crops are not tilled for the life of the stand, and .some heavy clay soils
inhibit the normal degradation processes, (undecomposed straw has been
unearthed after 2 years of burial).
In the mid 1940"s when blind seed fungus (Glocotima temulenta) was
infecting 90% of the perennial ryegrass crop of Western Oregon, open field
burning was recommended as a field sanitation measure (1). Burning proved
to be effective in controlling disease and served as an inexpensive means
of residue disposal. In addition, burning served to kill weed seeds on
the soil surface, reduce fertilization requirements, increase seed yields,
reduce fire danger, partially control insects and rodents, and release
minerals back to the soil. This practice was later adopted for other crops
as well, until in 1970, approximately 300,000 acres were burned.
156
-------
The major disadvantage of open field burning is that it contributes to
air pollution. According to a study by Boubel (1), particulate emissions
average 15,6 Ib/ton of fuel burned. Carbon monoxide, hydrocarbons, and
nitrogen oxides are also produced. Normally, these products would be dis-
persed in the upper atmosphere, but meterological studies have revealed
that the climatic conditions in the Willamette Valley are not always
conducive to smoke dispersion (3:23). During these times, particulate and
gaseous emissions are held near the ground, resulting in decreased visibility
and increased human annoyance.
The increasing acreage and tonnage of crop residue being burned,
coupled with the increase in population and the limitations of natural
atmospheric ventilation in the Willamette Valley, have led to a legis-
lative decision to ban field burning after January 1, 1975. This decision
will necessitate the development of alternative cultural practices for
field sanitation if Oregon is to retain its position as a major world
supplier of grass seeds. In 1968, Oregon produced 41% of all U.S. grass
and legume seeds on 308,000 acres at a sales value of $31 million. Eighty
one percent of this was produced in the Willamette Valley. Virtually all
of the U.S. ryegrass production is from 134,000 acres in the Willamette
Valley. This yield has a value of nearly $13 million (2).
A state supported research program is being conducted at Oregon State
University to develop alternative cultural practices to replace open field
burning. One alternative is the use of a mobile field sanitizer, a machine
capable of burning crop residues with less resultant air pollution, but
the physical removal of some of the straw will probably be required. The
industrial utilization of this straw for the production of useful products
will conserve a natural resource, provide an acceptable disposal method, and
could provide the farmer with an economic return to help defray the added
costs of straw removal. Denmark (4) has studied the production of a straw
particleboard, and since straw particleboard is one product with potential
for industrial utilization in home construction and finishing, furniture,
and decorative articles, this process is being studied at Oregon State
University as part of a research program supported by the Environmental
Protection Agency, State of Oregon, and Oregon Seed Council.
Engineering This analysis is designed to identify the major factors
Factors that contribute to the total product cost. A capacity of
100 tons/year of product has been selected to provide information for a
small pilot plant. This size of plant could be operated by tv/o employees
using readily available equipment and the product could be used to evaluate
physical properties and to determine market potential. Operative information
could be used for scale-up analyses. Since it is anticipated that modifica-
tions will be proposed to reduce both capital investment and total product
cost, this analysis is presented as a starting point for the development-
of a process to utilize .-aste straw.
A schematic design of the process is shown in Figures IV. B. 1. and IV.
B. 2. The plant would be constructed in a 40' x 40' steel building on a
concrete pad. Adequate storage area is available for the year's supply of
straw.
157
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The straw will be removed from the field and stored in 50-pound ha?as,
held with 2 strands of wire or string. The straw will be fed into a nri.l.
The milled straw will be carried by air to a cyclone separator where the
straw will be collected and the air will pass out of the top carrying the
fines. The fines will be collected in a bag.
If drying is required prior to the resin application, the straw will
be fed through a dryer and into a rotary mixer for the resin application.
Scales will be used to determine the resin concentration. Liquid resins
such as polyisocyanates, U. F., and P. F. will be applied by spraying with
compressed air. Solid resins such as acrylics or bakelite will be physically
mixed prior to pressing. The straw/resin mixture will be pressed into a
solid particleboard with a heated platen press. The density and size of
the board will be determined by the quantity of straw used and the pressure.
The board will be cut to finished size with a saw and a finish coat will be
applied if desired. The waste material will be returned to the mill for
recycling. The finished product will be stored for later utilization.
The following equipment is readily available for utilization in the
plant with a capacity of approximately 100 tons of product/year.
A hammermill of the type similar to a Ward's Model 6A hammermill with
a changeable screen is adequate for reducing the straw particle size. It
has an approximate capactiy of 150 pounds/hour. The straw is carried by
air to a cyclone separator where the chopped straw is collected. A cloth
bag can be utilized to filter the dust from the air. Approximate cost,
$260.00.
The dryer may be a rotary drum, fluid bed, or tray dryer, a more
economical way of drying might involve circulating hot air through the
cyclone separator. The heater, fan, and ducts could be fabricated for less
than $50.00. The dryer is left out of this schematic because laboratory
experimentation indicates that for some resins, the presence of water
vapor is not detrimental.
The mixer can be any one of several types of commercially available
ribbon blenders or rota-cone blenders with sprayers which can be used to achieve
a good spray coating of resin on the straw particles. This equipment is
availabJe in both small and large sizes but a suitable size for this plant
would cost approximately $5,000.00. Continuous resin application would
be possible using a Day Centri-Flo mixei© which can process over 600
pounds/hour.
A direct reading scale would be utilized to determine the resin con-
centration. Since batch sizes would be approximately 5 pounds or multiples
thereof and resin concentrations could vary from 5 - 10%, a 10-25 Ib. scale
with 2 ounce markings or 0.1 pound markings would be needed. Only one
scale would be needed with a container for transferring the straw from the
cyclone to the mixer and from the mixer to the press. Approximate cost,
$50.00.
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An automatic hydraulic press with heated platens 24.5 inches square
wouldfFe ideal for producing a 24 inch square board, however, the cost would
be over $8,000.00. Manual presses are not available as a stock item at this
size. Although normally a one-opening press, alterations could be made to
convert it to a multiple opening press in order to increase its capacity.
A small table saw could be used to cut the boards to finished dimension;
approximate cost, $50.00. The waste scraps would be fed back into the process
at the mill. The finished product would be stored for transportation to a
sales center or for utilization in making straw particleborrd products.
The equipment mentioned here would be useful for a manually operated
batch pilot plant. A study of the results of variations in process variables
on the properties of the product could be conducted, and the design
for a larger automated plant could be established. In addition,
a market study could be conducted to determine the market value of the
product.
Economic The industrial utilization of straw would be greatly
Considerations enhanced if a profitable process could be developed.
Profitability depends primarily on the cost of processing and the value
of the product. It is important to identify the contribution that the
various aspects of processing make to the total cost so that efforts can
be made to reduce the total cost of processing. It is also important to
identify the value of the product in its most likely applications. This
may necessitate the production of finished products for retail sales
evaluation.
A sample estimation of fixed capital investment and total product
cost for a 100 ton/year pilot plant using polyisocyanate resin is given
in Table IV. B. 2. and Table IV. B. 3. No additional equipment would be needed to
produce boards with other resins. This plant would be manually operated
by two men. ;
Indirect costs and general expenses are estimated based on the assumption
that this plant would be a part of a larger business enterprise requiring
some supervision and overhead expenses. If, for example, ten such plants
were located near grass seed farms to reduce transportation costs, super-
vision, clerical, sales, and maintenance support could be shared. These •
costs, then are listed at 1/10 of the total estimated cost for the larger
business enterprise.
The plant would be operated for 8 hours/day and 250 days/year. Since
capacity is rated at 200,000 pounds of product/year, the average daily
production rate would be 800 pounds or 100 pounds/hour.
The unit production cost is estimated at $0.15/lb product or $4.80
for a 4' x 8' x 1/4" r-heet with a density of 48 lb/ft-3. If the press
could be modified into a multiple opening press with no change in capacity
or operating cost, the cost for a sheet 4' x 8' x 1/8" could be reduced
to $2.40.
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The value of a straw particleboard made with polyisocyanate resin
has not been determined as yet, however, it has general appeal for use as
decorative interior home paneling. The cost of wood paneling ranges from
$2-8 for a 4* x 8' x 1/8" panel depending on quality and finish.
The value of straw particleboard for utilization in lamination or
furniture construction is difficult to estimate without a market survey
using actual samples, however, it is presumed that consumer acceptance will
be sufficient to establish a value higher than the estimated production
cost, even though the margin of profit will be low at this production rate.
The unit production cost could be lowered by automation and by increasing
plant capacity through the use of larger machines since operating labor
accounts for 47% of the total product cost. The use of lower resin concen-
tration or a different, less expensive resin, assuming no change in physical
properties, would make a slight reduction in the production cost since resin
costs account for 15% of the production cost. The cost of the straw accounts
for only 6i of the cost of the product.
*
Resins In the laboratory, six different resins have been received
Examined in order to evaluate the preparation of a solid board from
straw; bakelite, acrylic, transoptic powder, phenol-formaldehyde, urea-
formaldehyde, and isocyanate. The resin cost and the physical properties
of the product will be important factors in developing an industrial process.
Bakelite is a synthetic resin made from formaldehyde and phenol. It
was obtained in solid form and was ground to a powder prior to utilization.
Four colors have been used; black, red, green, and amber. The powdered
resin and milled straw were physically mixed prior to pressing at 350°F.
Acrylic resin was obtained as a ground-up white solid. Physical
mixing and pressing at 350°F produced a solid board. The resin becomes
transparent as it fuses.
Transoptic Powder, a finely ground solid, initially becomes fluid
as it is heated under pressure. Continued heating of a straw/powder
mixture produces a solid board. This resin also becomes transparent upon
fusion.
Phenol-formaldehyde is one of the resins used in wood particleboard
manufacture. It is normally sprayed onto the particles in a water solu-
tion. The water is driven off during the heating and pressing cycle when
the phenolic compound and the formaldehyde polymerize.
Urea-formaldehyde is also used in wood particleboard manufacture.
It is sprayed onto the particles in a water solution. A low pH is needed
to trigger the polymerization reaction and since wood contains acid groups
it is a very effective resin when used with wood. Since straw appears to
be neutral, it may not be as effective without adding an acidic compound.
160
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Polyisocyanate resins are used in conjunction with polyalcohols in the
production of polyurethane plastics. It was initially surmised
that the cellulose of straw could be utilized as the polyalcohol and
that a solid product should result if a polyisocyanate resin were mixed
with straw particles and heated under pressure. The term polyisocyanate
includes both diisocyanates and polyisocyanates in this report.
Since the polyisocyanate resins are liquid at room temperature, they
can be sprayed onto the straw particles. Solvent application is also
possible using DCM, acetone, toluene, or benzene.
A list of the resins obtained for straw particleboard formation is
provided in Table IV. B. 1.
161
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References
1. Boubel, R. W., E. F. Darley, and E. A. Schuch, "Omissions From Burning
Grass Stubble and Straw," Journal of the Air Pollution Control
Association, 19_, 497-500 (1969^.
2. Middlemiss, W. E., and R. 0. Coppedge, "Oregon's Grass and Legume Seed
Industry in Economic Perspective," Cooperative Extension Service,
Oregon State University, Corvallis, Oregon, Special Report 284,
April 1970.
3. "Research Relating to Agricultural Field Burning," Agricultural Experi-
ment Station and Air Resources Center, Oregon State University
Corvallis, Oregon, February 1971.
4. Personal Communication: Finn Rexen, Forskningsinstituttet for Handels-
O.G. Industriplantcr; 6000 Kolding, Holbergsvej 10, Denmark.
162
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Waste
Wire
or
String
i
Baled
Straw
i
1^
i— — 1-
Fines | Resin Water
' Water ! | ^
t i i
Size ) Product
Reduction •*" Drying 7"*" Mixing * Formation *" Finis
;hing
i
Figure IV. B. 1. Block Diagram Showing the Particleboard Process.
-------
Straw Bales
Wire
Waste
Fines
Bag
\ /
\ /
£
Air
I"- t— i
LZ3=TT=
Cyclone I I
Separator I I
Liquid
Resin
wywwwvi
Rotary
Mixer
t ,,, -3
Saw
Mill
Scales
Scales
Press
1
Storage
Figure IV, B. 2. Schematic Diagram of Straw Particleboard Plant.
-------
Table IV. B. 1. Resins Used in The Laboratory Study of Straw Particleboard
Identification Used
In This Report
Chemical Composition
Vendor
Bakelite
Acrylic
Trans-optic powder
PF
UF
TKI
PAPI
Isonate 125M
MR
MRS
Phenol-formaldehyde Buehler
Polyacrylic esters duPont
Buehler
Phenol-formaldehyde Borden
Urea-formaldehyde Borden
Tolylene 2,4 diisocyanate Aldrich
Polymethylene polyphenylisocyanate Upjohn
Diphenylmethane diisocyanate Upjohn
4,4 diphenylmethane diisocyanate Mobay
4,4 diphenylmethane diisocyanate Mobay
(others available)
dianisidine diisocyanate Carwin
tolidine diisocyanate Carwin
Hexamethylene diisocyanate Mobay
m-xylyene diisocyanate Carwin
2,4 tolylene diisocyanate Allied
4,4' diphenylmethane diisocyanate duPont
165
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Table IV. B. 2. ESTIMATION OF FIXED-CAPITAL INVESTMENT COST
Dollars
Plant Description:
Capacity:
Straw Particleboard - Pilot Plant
100 tons/year product
I. Direct Costs
A. Equipment 21,510
1. Purchased Equipment 13,410
a. Mill w/motor 260
b. Cyclone separator 40
c. Dust collector 10
d. Scale 50
e. Mixer w/sprayer 5,000
f. Press 8,000
g. Saw 50
2. Installation (35% P.E.) 4,700
3. Instruments 6 Controls (6% P.E.) 800
4. Piping (10% P.E.) 1,300
5. Electrical (10% P.E.) 1,300
B. Buildings 5,200
1. Steel Building 40' x 40' w/concrete pad 4,000
2. Doors, Windows, etc. 1,200
C. Service Facilities n/a
D. Land 200
II. Indirect Costs
A. Engr. fi Supervision (1/10 of 10% D.C.) 270
B. Const. 5 Contractor Fees (10% D.C.) 2,700
C. Contingency (5% F.C.I.) 1,600
III. Fixed Capital Investment
IV. Working Capital (10% T.C.I.)
V. Total Capital Investment
Peters, Max. S., and Timmerhaus, Klaus D., "Pilot Design and
Economics for Chemical Lngineers", P. 140, McGraw-Hill,
New York, 1968.
26,910
4,570
31,480
3,500
34,980
166
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Table IV. B. 3. ESTIMATION OF TOTAL PRODUCT COST1
Dollars
Plant Description: Straw Particleboard - Pilot Plant
Capacity: 100 tons/year product
I. Manufacturing Cost 27,660
A. Direct Production Costs -.. 23,780
1. Raw Materials 6,240
a. Straw ($15.00/ton) v 1,740
b. Resin ($0.45/lb) 4,500
2. Operating Labor (2 men) 14,000
3. Supervisory § Clerical (10% of O.L.) 1,400 x
4. Utilities 1,400 ,..-•'"'
a. electricity 1,200
b. phone 100
c. water 50
d. waste disposal 50
S. Maint., S Repairs (1/10 of 10% F.C.I.) 310
6. Operating Supplies (0.5% of F.C.I.) ISO
7. Laboratory Charges (1/10 of 20% O.L.) 280
8. Patents § Royalties (assume none)
B. Fixed Charges 2,380
1. Depreciation 1,440
a. equipment (10% P.E.) 1,340
b. buildings (2% value) 100
2. Taxes (2% F.C.I.) 630
3. Insurance (1% F.C.I.) 310
4. Rent (n/a)
C. Plant Overhead (5% T.P.C.) 1,500
II. General Expenses 3,080
A. Administrative Costs (1/10 of 5% T.P.C.) 180
B. Distribution and Selling (1/10 of 10% T.P.C.) 300
C. Research and Development (1/10 of 5% T.P.C.) 150
D. Financing (7% T.C.I.) 2,450
III. Total Product Cost 30,740
Unit Cost $30,740 = $0.15/lb
200,000 Ibs.
Peters, Max S., and Tinunerhaus, Klaus, D., "Plant Design and Economics
for Chemical Engineers", P. 141, McGraw-Hill, New York, 1968.
167
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