In: Maloney, T.M., ed. Proceedings of the 25th International
particleboard/composite materials symposium; 1991 April 9-11;
Pullman, WA. Pullman, WA: Washington State University; 1991:
COMPOSITES FROM RECYCLED MATERIALS
ROGER M. ROWELL JOHN A. YOUNGQUIST DOBBIN MCNATT
Forest Products Laboratory Forest Products Laboratory Forest Products Laboratory
Madison, WI Madison. WI Madison. WI
ABSTRACT Research and development needs for maximiz-
ing the benefits of using recovered waste mate-
A reduction is urgently needed in the quan- rials for composite products are discussed.
tities of industrial and municipal solid waste
materials that are being landfilled currently.
Major components of municipal solid waste INTRODUCTION
include waste wood, paper. plastics. fly ash.
gypsum. and other biomass fibers -- materials The word “waste” projects a vision of a
that offer great opportunities as recycled ingre- material with no value or useful purpose. How-
dients in wood composites. This paper dis- ever, technology is evolving that holds promise
cusses possibilities for manufacturing selected for using waste or recycled wood and, in some
composites from these materials. Methods for cases. even plastics to make an array of high-
producing the composites and the resultant prod- performance composite products that are in
uct properties and attributes are described. themselves potentially recyclable.
When fibers. resins. and other materials are posite waste. The use of resources that coexist
used as raw materials for products such as with wood-based resources is also considered,
paper. they require extensive cleaning and re- including a variety of plastics and other re-
finement. When recovered fibers. resins. and sources that “contaminate” the wood-based re-
other materials are used for the manufacture of source.
composites. these materials do not require ex-
tensive preparation. This greatly reduces the A comprehensive waste management pro-
potential cost of manufacturing. gram must rely on the aggregate impact of
several courses of action: waste reduction,
A case-in-point is the making of compos- recycling. waste-to-energy schemes. and land-
ites from recycled paper. In the United States. fill (Kovacs 1988). The greatest impact that is
nearly 80 million tons of 6,000 different paper likely to result from further research is in the
and paperboard products are produced and over area of recycling. Increased use of recycled
70 million tons are discarded each year. Few of biobased resources will allow the markets for
the paper products found in the municipal solid fiber composites to grow without increasing the
waste (MSW) stream are produced solely from use of virgin timber. Therefore. forest products
fiber and water. Each product consists of a fiber industries will benefit from such research be-
matrix to which some mineral or chemical com- cause less expensive raw materials will be avail-
pound is added to enhance the utility of the able for producing high quality composites.
product. Thus, many forms of wastepaper con-
tain contaminants (extraneous materials). The purpose of this paper is to describe the
Whether they are adhesives, inks, dyes, metal potential for producing selected composites from
foils, plastics, or ordinary household wastes, waste wood, paper. plastics, fly ash, gypsum.
these contaminants may need to be separated and other forms of waste biomass. First, the
from the wastepaper before the fiber can be availability of waste materials from the MSW
recycled into another useful paper product. This stream and the desirability of developing ways
is not the case with wood-based composites. In to recycle these materials into useful, high-
many uses, wood fiber composites of varying performing, value-added composites is dis-
types are opaque, colored. painted. or overlaid. cussed. Then methods for making selected
Consequently. recovered fibers, resins. or other composites are described briefly and product
materials used for composites do not require properties and attributes are discussed. Next,
extensive cleaning and refinement. Thus. com- composites made from combinations of wood
posites provide an unusually favorable option with other biobased fibers are reviewed. Fi-
for the recycling of several highly visible and nally, research and development needs for
troublesome classes of MSW – paper of vari- maximizing the benefits of using recovered
ous types, waste wood. plastic bottles, fly ash. waste materials for composite products are out-
gypsum, and other biobased fibers. lined.
This paper focuses on wood-based re-
sources that either presently enter or could enter MUNICIPAL SOLID WASTE AS
the recycling stream, both commercially and SOURCE OF MATERIALS
residentially. This includes newspaper, pack- FOR COMPOSITES
aging. and other forms of wood-based fiber
products. as well as all forms of industrial and A considerable amount of data is related to
residential solid-wood and wood-based com- the inventory of the U.S. MSW stream (Table
1). In 1988, paper and paperboard, wood, and trial production wastes, bark, and sawdust. These
plastics in the MSW stream accounted for ap- latter categories of wood waste also represent
proximately 71.8, 6.5, and 14.4 x 10 ton, potentially valuable sources of raw materials.
respectively. By the year 2000, these figures are
expected to increase to 96.1, 8.4, and 21.1 x 10 Many problems are associated with the use
ton annually (Environmental Protection Agency of waste materials, including collection, analy-
1990). In addition to the wood fiber in the MSW sis, separation, clean up, uniformity, form, and
stream, vast quantities of low-grade wood, wood costs. Assuming that these problems can be
residues, and industry-generated wood waste in overcome on a cost-effective basis, some of the
the form of sawdust, planer shavings, and chips resultant reclaimed materials should be useful
are now being burned or otherwise disposed of. ingredients for a range of valuable composites,
from low-cost, high-volume materials to high-
The data in Table 1 include all the residential cost, low-volume materials for a wide range of
waste products, but not all the industrial waste end uses.
materials. Data are available for the total vol-
ume or weight of certain wood-based products Source separation and recycling not only
in the MSW stream, such as paper, packaging, extends the life of landfills by removing mate-
and pallets, but only incomplete information is rials from the MSW stream, but also makes
available for timber thinnings, leaves, indus- available large volumes of valuable raw materi-
Table l.–Estimated distribution of materials generated in municipal solid waste
stream in 1988
Amount in MSW Stream
Source (%) (x 10 ton)
Paper and paperboard 40.0 71.8
Yard Waste 17.6 31.6
Metals 8.5 15.3
Food waste 7.3 13.2
Glass 7.0 12.5
Plastics 8.0 14.4
Textiles 2.2 3.9
Wood 3.6 6.5
Rubber-leather 2.6 4.6
Miscellaneous inorganics 1.5 2.7
Other 1.7 3.1
(Total) (100.0) (179.6)
Adapted from EPA report (1990).
als for use by industry in place of virgin re- ing and mixing: the mixture is extruded as
sources. Industrial use of such materials re- sheets that are subsequently shaped by
duces both costs for raw materials and the thermoforming into the final product. Limits on
energy it takes to make a finished product (New the melt viscosity of the mixture restrict the
York Legislative Commission 1986). The main amount of fiber or flour (to about 50 weight
requirement is that the recycled ingredients percent) as well as the length of the fibers that
meet the quality and quantity requirements of can be used. Fiber length is also limited by fiber
the consuming production operation. breakage as a result of the high shear forces
during melt mixing.
COMPOSITES FROM WASTEPAPER, In contrast. nonwoven mat technology in-
WOOD FIBER, PLASTICS, AND volves room temperature air mixing of ligno-
INORGANIC MATERIALS cellulosic fibers (or even fiber bundles) with
thermoplastic fibers. The resultant mixture
passes through a needling step that produces a
Wastepaper. wood. plastics, fly ash, gyp- low-density mat in which the fibers are me-
sum, and other biomass fibers can be reclaimed chanically entangled. The mat is then shaped
from industrial and MSW streams and used for and densified by a thermoforming step. With
several kinds of composite products: wood this technology. the amount of lignocellulosic
fiber-plastic composites. dry-formed wood fi- fiber can be greater than 90 weight percent. In
ber-based composites, inorganic bond wood addition. the lignocellulosic fiber can be
composites. and composites that combine wood precoated with a thermosetting resin; for ex-
fibers with other lignocellulosic fibers, metals, ample. phenol-formaldehyde. After
and glass. thermoforming. the product possesses good tem-
perature resistance. Because longer fibers are
required, this product can achieve better me-
Thermoformable Wood-Plastic chanical properties than that obtained with the
Fiber Composites melt-blending process. However. high wood
fiber contents lead to increased moisture sensi-
Thermoformable composites are classified tivity.
into two general types on the basis of the manu-
facturing process. Both processes-melt blend- It is virtually certain that virgin ingredients
ing and nonwoven mat formulation -- allow can be replaced by some recycled ingredients in
and require differences in composition and in melt blending and nonwoven mat formation for
the lignocellulosic component. many applications. For example. the thermo-
plastic polymer might be totally or partially
A typical composition for a melt-blended replaced by high-density polyethylene (HDPE)
composite is 40 to 60 weight percent wood flour from milk bottles. polyethylene terephthalate
or cellulose pulp fiber with a powdered or (PET) from beverage bottles, or even
pelletized thermoplastic such as polypropylene nonsegregated plastic mixtures from MSW.
or polyethylene. In the melt-blending process, Large quantities of a variety of industrial waste
the wood-based fiber or flour is blended with plastics are also available and should be consid-
the melted thermoplastic matrix by shearing or ered. The virgin lignocellulosic component
kneading. Currently, the primary commercial might be replaced by fibers from wastepaper or
process employs twin screw extruders for melt- waste wood. These substitutions offer potential
benefits in reducing both MSW and the cost of examined several types of pulp fiber in compos-
the composite processes. In some cases, the ites made with polypropylene and HDPE.
properties of the composite will probably be Shiraishi and colleagues showed improvements
improved; for example, by substituting waste- in mechanical properties as a consequence of
paper fibers for wood flour in the melt-blending using high-molecular-weight maleated polypro-
process. pylene instead of normal polypropylene (Kishi
et al. 1988, Takase and Shiraishi 1989). Finally,
Currently, the primary application of Maiti and Hassan (1989) measured the effects
thermoformed composites, both melt and of wood flour on the melt rheology of polypro-
blended and air laid, is for interior door panels pylene.
and trunk liners in automobiles. Additional
large-volume, low-to-moderate cost applica- At the Forest Products Laboratory (FPL) in
tions are expected in areas such as packaging Madison, Wisconsin, and the University of
(trays, cartons), interior building panels, and Wisconsin, Myers and others (in press, in prepa-
door skins. ration) investigated in some detail the influence
of a low-molecular-weight maleated polypro-
The following sections are not intended to pylene (Eastman’s Epolene E-43) on the me-
be a comprehensive review of recent research chanical and physical properties of wood flour
on wood fiber-thermoplastic composites. The and polypropylene-extruded composites. Ex-
effects of some important composition and pro- periments by Kolosik and others (unpublished
cessing variables in the composite processes are data) indicated that the E-43 probably is not
described, including preliminary indications of acting as a true coupling agent, but instead has
the effects of recycled ingredients. some effectiveness as a dispersing agent.
Research on Melt-Blended Publications are beginning to appear on the
Composites effect of recycled ingredients on the behavior of
melt-blended lignocellulosic-polyolefin com-
The 1980s brought a resurgence of re- posites. Selke and colleagues showed that com-
search into various aspects of melt-blended posites from aspen fiber and once-recycled blow-
composites made from wood-based flour or molding HDPE from milk bottles possessed
fiber in virgin thermoplastic matrices. For essentially equivalent strength and modulus
example, Kotka and colleagues published many properties as those of composites made from
papers in this area, emphasizing improvements virgin HDPE; however, impact energy was re-
in the filler-matrix bond throughcoupling agents duced (Selke et al. 1988, Yam et al. 1988).
and grafting of polymers on cellulosic fiber Woodhams and others (1990) found that com-
surfaces (Kotka et al. 1990, Maldas et al. 1988, posites made from polypropylene and pulp fi-
Maldas et al. 1989). Klason and colleagues bers or fiberized old newspaper possessed
carried out extensive investigations on the ef- strength and impact properties very similar, and
fects of several polymer and fiber types and the apparently much superior, to those of compos-
influence of a variety of processing aids and ites made from wood flour-polypropylene sys-
coupling agents (Dalvag et al. 1985, Klason et tems. In preliminary work at the FPL, the
al. 1984). Woodhams and others (1984, 1990) properties of wood flour-polypropylene and
The use of trade or firm names in this paper is for reader information and does not imply endorsement by the U. S.
Department of Agriculture of any product or service.
wood flour-HDPE systems have been com- erts’ patents were assigned to the Weyerhaeuser
pared with the properties of a fiberized old Company.
newspaper-HDPE composite. The differences
between wood flour-polypropylene and wood From 1966 to 1968, a series of patents
flour-HDPE systems were qualitatively consis- (Caron and Allen 1966.1968; Caron and Grove
tent with expectations based on the lower 1966a, b, c; Grove and Caron 1966) were issued
strength and greater flexibility of HDPE rela- and assigned to the Weyerhaeuser Company.
tive to polypropylene. Also. strength was im- These patents cover the use of a wood fiber-
proved by substituting fiberized old newspaper thermoplastic resin system in conjunction with
for wood flour. a thermosetting resin system. In the early 1970s.
Brooks (1990) developed a process that pro-
Research on Nonwoven Web duced a very flexible mat using a thermoplastic
Composites Vinyon fiber in combination with a thermoset-
ting resin system. The mat was fed through an
Numerous articles and technical papers oven to melt and set the Vinyon fiber without
have been written and several patents have been affecting the setting of the thermosetting resin
issued on both the manufacture and use of component. This process was patented in 1984
nonwoven fiber webs containing combinations by Doerer and Karpik and was assigned to the
of textile and cellulosic fibers. This technology Van Dresser Corporation.
is particularly well-known in the consumer prod-
ucts industry. For example. Sciaraffa and oth- Brooks also developed an interesting
ers (1982) were issued a patent for producing a method of recycling waste cellulosic materials
nonwoven web that has both fused spot bonds for the production of medium density fiber-
and patterned embossments for use as a liner board and paper (Brooks 1973). After being
material for disposable diapers. Bither (1980) shredded. sorted from other waste materials like
found that polyolefin pulps can serve as effec- plastic and metal. and steamed. the cellulosic
tive binders in nonwoven products. Many addi- fibers and fiber bundles are abraided under heat
tional references could be cited in this area. and pressure to break down any hydrogen bonds
and to soften any lignin and other resins. The
Brooks (1990) published a review of the resultant cellulose fibers are then mixed with
history of technological development for the resin. formed into a mat. and consolidated under
production and use of moldable wood products pressure to form flat fiberboard and paper prod-
and air-laid. nonwoven. moldable mat processes ucts.
and products. The first moldable wood product
using the wet slurry process was developed by Youngquist and Rowell (1989) reviewed
Deutche Fibrit during 1945 to 1946 in Krefeld, opportunities for combining wood with
West Germany (Brooks 1990). A moldable nonwood materials. This review included a
cellulose composition containing pine wood discussion of the materials and properties of
resin was patented by Roberts (1955) as well as composites consisting of wood fibers and bio-
a process for producing molded products from mass. metal. plastic, glass, or synthetic fibers.
this composition (Roberts 1956). The compo- In a recently published paper. Youngquist and
sition consisted of a mixture of comminuted others (1990) reported on the mechanical and
cellulose material and at least 10 percent of a physical properties of wood-plastic fiber com-
thermoplastic pine wood resin derived from the posites made with air-formed dry-process tech-
solvent refining of crude rosin. Both of Rob- nology. This paper reported the effect of spe-
cies, wood flour to polypropylene ratio, and nation with wood and polyester homopolymer
type of plastic fiber or plastic fiber-thermoset- fibers, formed a composite with greatly im-
ting resin blends on mechanical and dimen- proved mechanical properties compared to that
sional stability properties of pressed panels hav- of the other two composite formulations tested.
ing a density of 1 g/cm . Kryzysik and
Youngquist (in press) reported on the bonding Wood-Plastic Fiber Mat
of air-formed wood-polypropylene as a cou- Composites
pling agent between the hydrophilic wood and
the hydrophobic polyolefin materials. Wood and plastic fibers can be formed into
a web using nonwoven web technology. The
A number of preliminary trials were con- fibers are introduced into a turbulent air stream,
ducted at the FPL using recycled office waste- transferred via this air stream to a moving sup-
paper. shredded old newspapers. dry fiberized port bed. and subsequently formed into a con-
old newspaper, and fiberized demolition waste tinuous mat with low or high density. This mat
wood. The raw paper materials, which did not of intertwined fibers is then passed through a
have the ink removed, were reduced to a suit- needling operation where fish-hook-type needles
able form using several reduction methods. further intertwine and strengthen the fibers.
The ratio of wood to plastic in this matrix can be
The demolition waste was first sorted me- in the 95/5 weight percent range. The plastic
chanically and then manually to remove material (5%) can also be replaced with a long
nonwood materials, washed. and fiberized us- wood fiber-like jute or kenaf.
ing a pressurized refiner. The recycled wood-
based fibers were then air mixed with virgin One interesting application for low-den-
polyester or polypropylene. transferred by an sity fibermats is for mulch around newly planted
air stream to a moving support bed, needled, and seedlings. The mats provide the benefits of
subsequently formed into a continuous. low- natural mulch: in addition. controlled-release
density mat of intertwined fibers. fertilizers, repellents. insecticides, and herbi-
cides can be added to the mats as needed.
When polyester fibers were used, the wood Research results on the combination of mulch
fibers were sprayed with a liquid phenolic resin and pesticides in agronomic crops have been
prior to web formation. The use of a thermo- promising (Crutchfield et al. 1985). The addi-
plastic polyolefin-like polypropylene greatly tion of such chemicals could be based on silvi-
improved the dimensional stability of the com- cultural prescriptions to ensure seedling sur-
posite compared to that of the polyester copoly- vival and early development on planting sites
mer-containing composite. These results can where severe nutritional deficiencies, animal
probably be explained by the fact that the damage. insect attack, and weed problems are
polypropylene melts and. to some extent, par- anticipated. The Forest Service is conducting
tially encapsulates the wood fibers. In all cases, preliminary research on using fiber mats to
the ability of the polyester copolymer-contain- improve the survival of loblolly pine seedlings
ing composite to absorb impact energy was in southern Louisiana.
superior to that of the polypropylene-contain-
ing composite. This can be attributed to the fact Low-density fiber mats can also be used to
that the polyester maintains a fibrous matrix replace dirt or sod for grass seedling around new
whereas the polypropylene fibers melt and flow homesites or along highway embankments. The
under heat pressure. Phenolic resin, in combi- grass seed can be incorporated in a wood or jute
fiber mat. Fiber mats promote seed germination There is a great opportunity to produce
and good moisture retention. High-density fi- fiber-based composites of varying densities from
ber mats can be used for air filters or other types recycled wood fibers. One family of products,
of filters. The density of the mats can be varied, called Homasote, was first produced in 1916
depending on the material being filtered and the and is made from old newspapers and other
volume of material that passes through the mat groundwood paper (Post 1990). Other fiber-
per unit of time. The FPL is conducting prelimi- board-type products now on the market also use
nary work on developing wood fiber mats for all or partly recycled wood fiber as the raw
filters. All of the applications discussed for material base stock. Uses for these types of
wood fiber mats can provide excellent outlets products include insulating acoustical board;
for recycled wood fiber. carpet board: wall. ceiling. and floor acoustical
insulation panels; nail baseboard; and floor and
Dry-Formed Wood-Fiber- roof insulation boards. It is anticipated that
many other uses for wood fiber-based products
Wood fiber-based composites are made will be developed as collection, separation, and
clean-up processes are further refined and de-
from reconstituted wood: the wood is first
reduced to fibers or fiber bundles and then put veloped.
back together by special manufacturing pro-
cesses into panels of relatively large size and Research is now being conducted at FPL to
determine the dimensional stability, moisture
moderate thickness. In final form, the panel
materials retain some properties of the original resistance, stiffness, and strength properties of
dry-process hardboards. The hardboards are
wood, but because of the manufacturing meth-
made from varying blends of virgin wood fiber
ods, the materials also gain some different prop-
erties. Because these products are manufac- and old newsprint fiber.
tured, they can be and are tailored to satisfy a
particular end-use or group of end-uses.
Inorganic-Bonded Wood Composites
Essentially, wood fiber-based composites
are made by breaking down wood to fibers Wood particles or fibers held together with
through thermal-mechanical or mechanical pro- an inorganic matrix, such as Portland cement or
cesses. The fibers are interfelted in the reconsti- gypsum, form a composite that can be used in a
tution process and are characterized by a bond variety of structural and industrial applications
produced by the interfelting. The composites (Moslemi 1990). These composites have an
are frequently classified as fibrous-felted board unique advantage over some conventional build-
products. At certain densities under controlled ing materials because they combine the charac-
conditions of hot pressing, rebonding of the teristics of both the wood fiber and mineral
lignin effects a further bond in the resultant matrix. Some of these composites are water
panel product. Binding agents and other mate- resistant and can withstand the rigors of outdoor
rials may be added during manufacture to in- applications, and almost all are either fireproof
crease strength or resistance to fire, moisture, or or highly fire-resistant and are very resistant to
decay. These materials include rosin, alum, attack by decay fungi.
asphalt. paraffin, synthetic and natural resins,
preservative and fire-resistant chemicals, and These types of composites, which provide
drying oils. Wax sizing is commonly added to another major future recycling opportunity to
improve water resistance. utilize waste wood and other postconsumer
wastes, are made by blending proportionate to be recycled will somewhat dictate the type of
amounts of the wastes with inorganic materials. size-reduction or comminution equipment se-
The most apparent and widely used example is lected to process the waste wood. The type of
cement. Portland cement, when combined with equipment, in turn, will determine the final size
water, immediately begins to react in a process and character of the resulting aggregate. For
called hydration to eventually solidify into a example, certain types of size-reduction equip-
solid stonelike mass. When fine sand and ment (shredders, pulverizers, hammermills,
coarse stone, the traditional aggregates, are augers) might be best suited to convert waste
blended with the cement and water paste, the wooden pallets, wood reels, stumps, and hous-
materials are bound together to form concrete. ing demolition material into shredded fiber
The strong bond between the paste and the bundles for use as concrete aggregate. On the
aggregate occurs as each cement particle estab- other hand. a completely different kind of ma-
lishes a type of surface growth that spreads by chine (wood chipper or chunker) might be pre-
linking with other cement particles and the ferred for reducing unmerchantable trees and
aggregate. tree trimmings into chips or chunks.
A special category of concrete is structural Besides wood waste, other postconsumer
lightweight concrete. Because lightweight con- wastes such as glass and plastic can also be used
crete is made entirely or partially with light- as concrete aggregate. Depending on the type
weight aggregates, such as burnt clay, pumice, or types of aggregate used and the proportionate
expanded blast furnace slag, and expanded ver- blend of materials in the resulting concrete, the
miculite, its principal unique property is its end properties may differ somewhat, but gener-
lower density compared to normal-weight con- ally, the product would be classified as low- to
crete. This makes lightweight concrete attrac- medium-strength concrete, for which there are
tive for reducing dead loads in structures with many potential applications.
concrete floor or roof fills. Generally, light-
weight concrete also has superior insulating Other inorganic waste materials that can be
properties. Concrete made with waste wood added to the concrete mix or used indepen-
will be lightweight and have high insulating dently to produce a different kind of composite
value. material are fly ash and flue gas gypsum. The
extremely finely grained fly ash, which is pro-
As an aggregate for concrete, wood can be duced during the combustion process and espe-
used in many forms. The wood aggregate may cially during the incineration of coal fuels, is
be a gradation of wood chunks, wood chips collected by mechanical or electrostatic pre-
(typical of the chips used by the pulp and paper cipitators. Flue gas gypsum, now being pro-
industry), shredded fiber bundles, sawdust, and duced in very large quantities because of Clean
even individual wood fibers (such as in a pulp Air Act regulations, is the result of introducing
slurry or that produced from recycled wastepa- lime into the combustion process to reduce
per). For example, the North Central Forest sulphur dioxide emissions. By 1995, more than
Experiment Station of the USDA Forest Ser- 100 power plants throughout the United States
vice in Houghton, Michigan, is developing a will be producing gypsum. Flue gas gypsum
product called Chunkrete, which uses wood can be used in lieu of mined gypsum.
chunks, particles, or fibers to substitute for or
partially replace gravel or stone aggregate. The Gypsum-bonded wood-fiber panels are
type or character of bulky wood waste material used as replacements for gypsum wallboard and
are reported to have strong nail- and screw- produce composites for various applications–
holding properties: high moisture and fire resis- from furniture to structural wall panels.
tance; and improved impact. mold, and mildew
resistance (Donnell 1990). Other reported ad-
vantages include improved anti-sag properties RESEARCH AND
(for ceiling boards), better sound insulation, DEVELOPMENT NEEDS
and easy installation (‘joints do not require tap-
ing). The USDA Forest Service. by virtue of its
role as steward of the National Forests, its
The combination of wood fibers with inor- research mission, and its longstanding expertise
ganic binders provides an unique opportunity to in wood-based composites and recycling re-
utilize recycled, waste, and low-grade wood search at the FPL, is actively engaged in a high-
fiber. Research has indicated clearly that inor- priority research program on alternative uses
ganic-bonded wood composites can meet struc- for recovered materials from the MSW stream.
tural and industrial needs. The FPL research program is focusing on devel-
oping value-added composites from waste ma-
terials, including wood-plastic fiber compos-
Wood-Biomass Fiber Composites ites, dry-formed wood fiber-based composites,
and composites fabricated with inorganic bind-
Wood is only one biobased resource in the ers. For each of these program areas, we are:
waste stream. Other biobased resources include
yard waste, water plants, and agricultural resi- 1. Developing methods for converting
dues. Yard waste is a major co-mingled source recovered fibers into forms suitable
of biobased fiber that is now considered only for for subsequent processing into altema-
composting. This is a vast resource that could tive end-use applications.
be combined with the wood-based resource to
produce composites of many different types. 2. Optimizing laboratory methods for
Many lakes and waterways suffer from an over- making prototype products.
production of water plants. These unwanted
plants create another large waste stream that 3. Developing a performance data base,
could also be considered as a valuable source of including determining mechanical and
industrial fiber if they could be collected and physical properties of wood-based
processed economically and combined with the products and conducting analytical
wood-based resource to produce composites. tests.
Because most recycling plans call for the
composting or burning of this portion of the 4. Determining the potential for recy-
waste stream. very little thought has been given cling composites with minimal loss of
to using yard waste and water plants for com- properties.
5. Studying product applications and
Agricultural residues, such as straw, rice economic viability of alternative end-
hulls, bagasse, and corn stalks, also represent a use applications.
vast resource that can be used to make compos-
ites of many different types. In some parts of the In each of these research areas, economic
world, these products are already being used to and laboratory studies are being conducted on
an iterative basis as a means of setting rs-search ber recycling program. As part of this effort. the
priorities and guiding process development. FPL has formed a multidisciplinary team of
The research will focus on the components of government. university. and industry special-
successful recycling systems through determin- ists to prepare a detailed problem analysis to
ing the supply and availability of waste wood focus research on composite from recycled
fiber. analyzing the economic efficiency of pro- materials. Some material in this problem analy-
cessing concepts. and studying the market po- sis was used in the preparation of this paper. We
tential for products made from recovered fiber. wish to acknowledge the following individuals
Studies will examine the effect of new tech- who are participating in this effort.
nologies on the environment. such as the pro-
jected impact on the landfill burden and on the
quality of the air. forests, soil. and water. The Government Representatives
studies will also examine the broader economic
impact of these technologies on timber markets Rodger A. Arola
and trade. USDA Forest Service
North Central Forest Experiment Station
Forestry Sciences Laboratory
CONCLUDING REMARKS Forest Hill Road
Houghton, MI 49931
Recycling is a critical element in the long-
term management of renewable resources. A Richard W. Hemingway
successful approach to recycling requires full USDA Forest Service, Southern Station
cooperation between the government and the Alexandria Forestry Center
private sector. Government cannot logically 2500 Shreveport Highway
mandate the increase use of recyclable materi- Pineville, LA 71360
als without the involvement of industry – the
industrial sector has the technical knowledge Henry Spelter
and equipment to separate and process solid USDA Forest Service. Forest Products
waste and to make useful, economically viable Laboratory
products from waste materials. Industry pro- One Gifford Pinchot Drive
vides the market for recycled resources. and it Madison, WI 53705
must be a full partner in all aspects of the
process. It is believed that by using recovered
wood and fiber for wood-based composites University Representatives
tremendous opportunities are presented for
growth. for progress. and for further industry John Simonsen
competitiveness in a world that is rapidly con- USDA Forest Service. Forest Research
suming many nonrenewable resources at an Laboratory
ever increasing rate. Oregon State University
3015 SW Western Avenue
Corvallis, OR 97331
The USDA Forest Service is developing a Michigan State University
comprehensive wastepaper and waste wood fi- Michigan Biotechnology Institute
3900 Collins Road duced by using this mat process. Pro-
P. O. Box 27609 ceedings, 1990 Tappi Nonwovens Con-
Lansing. MI 48909 ference. pp. 87-108.
Don White Caron, Phillip E. and Allen, G. D. 1968. Rein-
University of Arizona forced Moldable Wood Fiber Mat and
College of Engineering and Mines Method of Manufacture. U.S. Patent
Tucson, AR 85721 3,367,820. U. S. Patent Office. Wash-
ington. D. C.
Industry Representatives Caron, Phillip E. and Grove, G. A. 1966a.
Process for Manufacturing Moldable
Phil Davis Fibrous Panels. U.S. Patent 3,230,287.
Environmental Recovery Systems, Inc. U. S. Patent Office. Washington, D.C.
1625 Broadway, Suite 2600
Denver. CO 80210
Caron, Phillip E. and Grove, G. A. 1966b.
Production of Hot-Pressed Three-Di-
mensional Fiber Articles. U. S. Patent
3,261,898. U. S. Patent Office. Wash-
Technical Research Center
ington, D. C.
Tacoma. WA 98477
David Leneke Caron, Phillip E. and Grove, G. A. 1966c.
Wilsey & Ham Pacific Method of Die-Baking Moldable Wood
Solid Waste Projects Group Fiber Parts. U.S. Patent 3,265,791. U.S.
Portland, OR 97201 Patent Office. Washington, D. C.
Crutchfield, D. A.; Wicks, G. A.; and Burnside,
O. C. 1985. Effect of winter wheat
REFERENCES CITED (Triticum aestivum) straw mulch level
on weed control. Weed Sci. 34 (1): 110-
Bither, P. 1980. Polyolefin pulps as nonwoven
binders. Proceedings, Air-Laid and
Advanced Forming Conference. Dalvag, H.; Klason, C.; and Stromvall, H.-E.
November 16-18, 1980. Hilton Head 1985. The efficiency of cellulosic fill-
Island. S.C. ers in common thermoplastics. Part II.
Filling with processing aids in coupling
Brooks, S. Hunter. 1973. Method of Recycling agents. Intern. J. Polym. Mater. 11:9-
Waste Cellusic Materials. U.S. Patent 38.
3,741.863. U.S. Patent Office. Wash-
ington, D.C. Doerer, Richard P. and Karpik, J. T. 1984.
Moldable Fibrous Mat and Product.
Brooks, S. Hunter. 1990. Air lay nonwoven U. S. Patent 4,474,846. U. S. Patent
moldable mat process and products pro- Office. Washington, D. C.
Donnell, Rich. 1990. Highland American Maiti, S. N. and Hassan, M. R. 1989. Melt
starts up only gypsum fiberboard plant rheological properties of polypropylene-
in U. S. Panel World 31(6):5-11. wood flour composites. J. Appl. Polym.
Environmental Protection Agency. 1990. Char-
acterization of Municipal Solid Waste Maldas, D.; Kokta, B. V.; Raj, R. G.; and
in the United States: 1990 Update. Daneault, C. 1988. Improvement of the
ReportEPA/530-SW-90-042. U. S. En- mechanical properties of sawdust wood
vironmental Protection Agency. Wash- fiber-polystyrene composites by chemi-
ington, D. C. cal treatment. Polymer. 29: 1255-1265.
Grove, Gene A. and Caron, P. E. 1966. Method
Maldas, D.; Kokta, B.V.; and Daneault, C.
of Making a Moldable Wood Fiber Mat
1989. Influence of coupling agents and
with Metal Insert. U.S. Patent 3,279,048.
treatments on the mechanical proper-
U. S. Patent Office. Washington, D. C.
ties of cellulose fiber-polystyrene com-
posites. J. Appl. Polym Sci. 37-751-
Kishi, H.; Yoshioka. M.; Yamanoi, A.; and
Shiraishi, N. 1988. Composites of wood
and polypropylenes I. Mokuzai
Gakkaishi 34(2):133-139. Moslemi, A. A. 1990. Mineral bonded wood
composites: emerging technologies.
Klason, C.; Kubat, J.; and Stromvall, H.-E. Proceedings, IUFRO XIX World Con-
1984. The efficiency of cellulosic fill- gress. Montreal, Canada. August 5-11.
ers in common thermoplastics. Part I. pp. 299-312.
Filling without processing or coupling
agents. Intern. J. Polym. Mater. 10:159- Myers, G. E.; Chahyadi, I. S.; Coberly, C. A.;
187. and Ermer, D. S. [In press]. Woodflour/
polypropylene composites: Influence
Kokta, B. V.; Maldas, D.; Daneault, C.; and of maleated polypropylene and process
Beland, P. 1990. Composites of poly and composition variables on mechani-
(vinyl chloride) and wood fibers. Part cal properties. Intern. J. Polym. Mater.
II. Effect of chemical treatment. Polym.
Compos. 11(2):84-89. Myers, G. E.; Chahyadi, I. S.; Gonzalez, C.;
Coberly, C. A.; and Ermer, D. S. [In
Kovacs, W. L. 1988. The coming era of conser- preparation]. Composites from wood
vation and industrial utilization of recy- flour and polypropylene or high density
clable materials. Ecology Law Quar- polyethylene: Influence of maleated
terly 15(4):537-625. polypropylene concentration and extru-
sion temperature on properties. Intern.
Krzysik, Andrzej M. and Youngquist, J. A. [In J. Polym. Mater.
press]. Bonding of air-formed wood-
polypropylene fiber composites. In-
tern. J. Adhesion and Adhesives. New York Legislation Commission on Solid
B u t t e r w o r t h - H e i n e m a n n , Ltd. Waste Management. 1986. The eco-
Guildford, Surrey, United Kingdom. nomics of recycling municipal waste.
Post, Howard. 1990. The homosote story. Woodhams. R. T.; Law, S.; and Baltinecz. J. J.
Wood Based Panels Intern. 10(7):23. 1990. Properties and possible applica-
tions of wood fiber-polypropylene com-
Roberts, J. R. 1955. Moldable Cellulose Com- posites. Proceedings, Symposium on
position Containing Pine Wood Resin Wood Adhesives. May 16-18. Madi-
and Molded Product. U. S. Patent son, WI,
2,714,072. U. S. Patent Office. Wash-
ington, D. C. Yam, K.; Kayankai, S.; Selke, S.; andLai, C. C.
1988. Mechanical properties of wood
Roberts, J. R. 1956. Process of Forming Molded fiber/recycled HDPE composites.
Cellulose Products. U. S. Patent ANTEC 1988. pp. 1809-1811.
2,759,837. U. S. Patent Office. Wash-
ington, D. C.
Youngquist, John A. and Rowell, Roger M.
Sciaraffa, M. A.; Thome, D. G.; and Bogt, C. M. 1989. Opportunities for combining
1982. Soft, Bulky, Lightweight Non- wood with nonwood materials. Pro-
woven Web and Method of Producing. ceedings, Twenty-Third Washington
U. S. Patent 4,333,979. U. S. Patent State University International Particle-
Office. Washington, D. C. board/Composite Materials Symposium.
T. M. Maloney, Editor. Washington
Selke, S. E.; Yam. K. L.; Gogoi, B .; and Lai, C. State University. Pullman, WA. pp.
C. 1988. Compounding Wood Fibers 141-157.
and Recycled High Density Polyethyl-
ene Using a Twin-Screw Exturder. Youngquist, John A.; Muehl, J.; Krzysik, A.;
Abstract. Cellulose, Paper and Tex- and Tu Xin. 1990. Mechanical and
tile Div. ACS Meeting. June. physical properties of wood/plastic fi-
ber composites made with air-formed
Takase, S. and Shiraishi, N. 1989. Studies on dry-process technology. Proceedings,
composites from wood and polypro- 1990 Joint International Conference on
pylenes, J. Appl. Polym. Sci. 37:645- Processing and Utilization of Low-
659. Grade Hardwoods and International
Trade of Forest-Related Products, S. Y.
Woodhams, R. T; Thomas, G.; and Rodgers, D.
Wang and R. E Tang, Eds. National
K. 1984. Wood fibers as reinforcing
fillers for polyolefins. Polym. Eng. Sci. Taiwan University. Taiwan. pp. 159-
Printed on recycled paper