Patent Application: US-82863401-A

Abstract:
this invention relates to novel composites comprising plastic and plant material derived from members of parthenium spp . and , in particular , parthenium argentatum , parthenium tomentosum or parthenium incanum . the invention is also directed to composites that possess insect , fungal , and microbial resistance . products made from composites of the instant invention are useful to make numerous items , particularly those used for construction such as lumber , plywood , particleboard , fiberboard , poles , railroad crossties , or the like .

Description:
before the composites comprising plant material derived from the genus parthenium and plastic are disclosed and described , it is to be understood that this invention is not limited to the specific plastics or varieties of parthenium spp . described below , or to methods of making , as they may vary . it is also to be understood that the terminology used herein is for the purpose of describing particular embodiments , and is not intended to be limiting . unless defined otherwise , all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs . although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention , the preferred methods and materials are now described . all publications and patents mentioned herein are incorporated herein by reference in their entirety to disclose and describe the methods and / or materials in connection with which they are cited . the scope of the present invention is not limited to the uses discussed above or to the specific examples described below . parthenium species include parthenium argentatum , parthenium tomentosum , and parthenium incanum . other parthenium species are listed in hammond , b . l . and polhamus , l . g . 1965 . research on guayule ( parthenium argentatum ): 1942 - 1959 . usda tech . bulletin no . 1327 . 157 pp . and rodriguez , e . 1975 . parthenium argentatum , commonly known as guayule , is the plant from which latex and rubber is extracted . the term parthenium spp . plant material refers to material derived from one or more species of plants of the genus parthenium , including but not limited to whole plants ; plant parts , for example , stems , branches , leaves , roots , bark ; bagasse ; and combinations thereof . plant material derived from parthenium spp . may be combined with plant material from one or more plants of other than the genus parthenium to make the composites of the invention . naturally occurring resin extracted from parthenium spp . may be combined with plant material from parthenium spp . to make the composites of the invention . the parthenium spp . plant material is processed in any manner known in the art of wood processing , including , for example , by mechanical or chemical reduction . examples of mechanical reduction include grinding , chopping , milling , chipping , flaking , refining , and the like . processed parthenium spp . plant material includes but is not limited to fibers , fiber bundles , particles , flour , chips , flakes , fines , sawdust , pellets , strands , wafers , and combinations thereof an example of chemical reduction is chemical pulping . bagasse is the parthenium spp . plant residue after a component , e . g . latex , is removed . fibers are slender , threadlike elements of a plant which are comparatively long , between 40 to 300 mm , narrow , and tapering . particles , flour , chips , flakes , fines , sawdust , strands , and wafers are distinct fractions of plant material produced mechanically . natural plant resins are any of various solid or semisolid , viscous , usually clear or translucent , yellowish or brownish , organic substances naturally produced from various plants and trees ; these resins are insoluble in water , but are soluble in polar organic solvents such as ketones , ethers , alcohols , etc . and are used commercially in varnishes and lacquers , and as modifiers in synthetic plastics . natural plant resin is found in whole parthenium spp . plant in the range of about 10 to 15 % and in similar concentration in parthenium spp . bagasse after latex extraction . because latex extraction is done by a water - based process , little of the plant resin is removed . the percent resin is a w / w measure of oven - dried plant material at about 100 ± 2 ° c . guayule resins are compounds in the guayule plant extractable by polar organic solvents , the more traditional being acetone or methanol . other solvents , such as xylene can be used , but they will also remove the rubber with the resin fraction . latex is a stable emulsion consisting of small rubber particles suspended in a water solution . in the hevea plant , the latex is contained in ducts , exudes from a wound , and the exudant is collected . in contrast , in the guayule plant , the latex is contained in the plant cells and must be removed by maceration in the presence of organic solvents or water . for obtaining latex from the guayule plant , the plant material must be ground in the presence of a water - based extractant . an emulsion is obtained that is stabilized with an antioxidant and ammonium hydroxide for ph adjustment ( greater than 9 . 0 ). in contrast , when an organic solvent is used , the rubber is not in the emulsion form and instead is dissolved in the solvent . lignocellulosic materials are any of several combinations of lignin , cellulose , and hemicellulose , forming the essential part of woody tissue . plastic is a material that contains as an essential ingredient one or more organic polymeric substances of large molecular weight , is solid in its finished state , and , at some stage in its manufacture or processing into finished articles , can be shaped by flow . more specifically , these are materials formed from synthetic resins through the application of heat , pressure , or both . most starting materials prior to the final fabrication of plastic products exhibit more or less plasticity — hence the term plastic . however , the great majority , but not all , of plastic end products are quite non - plastic , i . e ., they are non - flowing , relatively stable dimensionally , and are hard . plastics that are relevant to this invention fall into two broad categories : 1 ) thermoplastics which can be heated and softened innumerable times without suffering any basic alteration in characteristics ; and 2 ) thermosetting plastic resins which once set at a temperature critical to a given material cannot be re - softened and re - worked . examples of thermoplastics that can be used in this invention include acrylonitrile - butadiene - styrene ( abs ) resins , acetals , nylons ( polyamides ), high and low density ( hdpe and ldpe , respectively ) polyethylenes ( including co - polymers ), polypropylenes ( including co - polymers ), polystyrenes , and vinyls . examples of thermosets that can be used in this invention include alkyds , allylics , the aminos ( melamine and urea ), epoxies , phenolics , polyesters , silicones , and urethanes . composite is a product made up of plant materials and a thermoplastic or a thermoset resin such that the product is bonded together and performs as a single unit . processes for making composites include melt - blending , air - laying , and compression molding . adhesive is a plastic substance capable of holding materials together by surface attachment . bond is the union of materials by an adhesive , or to unite materials by means of an adhesive . melt - blending is the process of combining a thermoplastic resin and a processed plant material using heat and shear forces to facilitate intimate mixing of the two components . when melt - blending technology is used , it is preferred that the thermoplastic material have a melting point below the decomposition temperature of the plant material . air - laying is the process of using high volumes of air to form an intimate and well - mixed layer of thermoplastic fibers and processed plant material that can subsequently be compression molded into a final product using a platen press and heat and pressure . this process can also be used with processed plant material and thermoset resins . compression molding is the process of pressing a mixture of either thermoplastics or thermosets and processed plant material into a final product configuration using heat and pressure and a platen press . compounding is the feeding and dispersing of the processed plant material component in a molten thermoplastic to produce a homogeneous material . astm ( american standards for testing materials ) standards establish in great detail how a particular test is to be conducted . astm standards are set to insure that test results are comparable from one test location to another test location . ansi ( american national standards institute ) standards state that in laboratory tests , specimens show certain minimally acceptable physical and mechanical properties , identified by numerical values . the test values give some indication of product quality . the fiber - plastic composites of the present invention were tested according to these standards against known particle and fiber products . the american national standards institute product standards for both particleboard and medium density fiberboard are sponsored by the composite panel association in gaithersburg , md . 1 . processing the parthenium spp . plant material to the desired form , for example by mechanical or chemical reduction . 2 . drying the processed parthenium spp . plant material to a selected moisture content . 3 . combining or blending the processed , dried parthenium spp . plant material and plastic to achieve substantially uniform mix . 4 . treating the mixture to form a composite , for example , by melt - blending , air - laying or compression molding . in general , the moisture content of the plant and plastic materials used to fabricate the composites of the invention should be below about 1 % when used in the melt - blending process , and below about 20 % when used in the air - laid or compression molding processes . selection of a moisture content of the starting materials is determined by procedures known in the art of composite manufacture . parthenium spp .— plastic composites may be made from mixtures of parthenium spp . plant material and either thermoplastic resins ( virgin , recycled , or a combination of both virgin and recycled plastics ) or thermoset resins . it is also possible to use materials that do not melt ( such as plastic , glass or carbon fibers , for example ), but serve as a reinforcing matrix , along with the thermoplastic or thermoset resins . for thermoplastic resins , the proportions of plastic to processed , dried plant material for this invention may range on a weight / weight basis from 95 % plastic : 5 % plant material to 5 % plastic : 95 % plant material , depending on the technique used . using melt - blending technology , the proportions of plastic to wood may range from about 95 % plastic : 5 % plant material to 25 % plastic : 75 % plant material . using air - laid technology , the proportion of plastic to processed , dried plant material may range on a weight / weight basis from 95 % plastic : 5 % plant material to 5 % plastic : 95 % plant material . for thermoset resins generally used in the compression molding process , the proportions of thermoset resin to processed , dried plant material on a weight / weight basis ranges from 15 % thermoset resin : 85 % plant material to 3 % thermoset resin : 97 % plant material . other ranges of the proportions of plastic to plant material for thermoplastic resins using melt - blending technology are 80 % plastic : 20 % plant material to 30 % plastic : 70 % plant material . using air - laid technology , the proportion of plastic to wood may also range from 80 % plastic : 20 % plant material to 20 % plastic : 80 % plant material or from 60 % plastic : 40 % plant material to 40 % plastic : 60 % plant material . the composites of the invention comprising parthenium spp . plant material and plastic are useful for making insect - and fungal - resistant wood products . in one embodiment , the composite of the invention exhibits at least about 30 % decrease in termite infestation relative to a composite not containing plant material derived from the genus parthenium or 30 % decrease in the number of termites alive after exposure to the composite for one week , preferably at least about 50 % decrease in termite infestation or decrease in the number of termites alive , more preferably at least about 71 % decrease in termite infestation or decrease in the number of termites alive , even more preferably at least about 80 % decrease in termite infestation or decrease in the number of termites alive , even more preferably at least about 93 % or 95 % decrease in termite infestation or decrease in the number of termites alive , and most preferably 100 % decrease in termite infestation or decrease in the number of termites alive . in another embodiment , the composite of the invention exhibits a rating of resistant or highly resistant to gleophyllum trabeum or poria placenta decay fungi as determined by astm standard test d - 2017 . broadly defined , a thermoplastic softens when heated and hardens when cooled . thermoplastics selected for use with the parthenium spp . plant material should generally melt or soften at or below the degradation point of the plant material component , normally 200 ° c . to 220 ° c . ( 392 ° f . to 428 ° f .). these thermoplastics include polypropylene , polystyrene , vinyls , and low - and high - density polyethylenes . wood flour is a readily available resource that can be used as a filler in thermoplastic composites . wood flour is processed commercially , often from post - industrial materials such as planer shavings , chips , and sawdust . several grades are available depending upon wood species and particle size . wood fibers , although more difficult to process compared with wood flour , can lead to superior composite properties and act more as a reinforcement than as a filler . in a similar matter , plant material like parthenium spp . flour or fibers , for example , can be used alone or blended with wood or other plant materials and thermoplastics . other materials can be added to affect processing and product performance of parthenium spp .— thermoplastic composites . these additives can improve bonding between the thermoplastic and plant material component ( for example , coupling agents ), product performance ( impact modifiers , uv stabilizers , flame retardants ), and processability ( lubricants ). several considerations must be kept in mind when processing plant material with thermoplastics . moisture can disrupt many thermoplastic processes , resulting in poor surface quality , voids , and unacceptable parts . materials must either be pre - dried or vented equipment must be used to remove moisture . the low degradation temperature of the plant material must also be considered . as a general rule , melt temperatures should be kept below 200 ° c . ( 392 ° f . ), except for short periods . higher temperatures can result in the release of volatiles , discoloration , odor , and embrittlement of the wood component . there are two main strategies for processing thermoplastics in plant material - composites ( youngquist et al ., 1994 ). in the first , the plant material component serves as a reinforcing agent or filler in a continuous thermoplastic matrix . in the second , the thermoplastic serves as a adhesive to the majority plant material component . the presence or absence of a continuous thermoplastic matrix may also determine the processability of the composite material . in general , if the matrix is continuous , conventional thermoplastic processing equipment may be used to process composites ; however , if the matrix is not continuous , other processes may be required . for the purpose of discussion , we present two examples for composites with high and low thermoplastic content . in composites with high thermoplastic content , the thermoplastic component is in a continuous matrix and the plant material component serves as a reinforcement or filler . in the great majority of reinforced thermoplastic composites available commercially , inorganic materials ( for example , glass , clays , and minerals ) are used as reinforcements or fillers . plant materials offer some advantages over inorganic materials ; they are lighter , much less abrasive , and renewable . as a re - inforcement , plant materials can stiffen and strengthen the thermoplastic and can improve thermal stability of the product compared with that of unfilled material . thermoplastics in pellet form have bulk density in the range of 500 to 600 kg / m 3 ( 31 to 37 lb / ft 3 ). plant materials typically have an uncompacted bulk density of 25 to 250 kg / m 3 ( 1 . 6 to 16 lb / ft 3 ). fibers are at the low end of the plant material bulk density continuum and wood flours at the high end . although processing of wood flour in thermoplastics is relatively easy , the low bulk density and difficulty of dispersing fibrous materials make plant fiber - thermoplastic blends more difficult to compound . more intensive mixing and the use of special feeding equipment may be necessary to handle longer natural plant fibers . the manufacture of thermoplastic composites is usually a two - step process . the raw materials are first mixed together , and the composite blend is then formed into a product . the combination of these steps is called in - line processing . in - line processing can be very difficult because of control demands and processing trade - offs . as a result , it is often easier and more economical to separate the processing steps . compounding is the feeding and dispersing of the plant material component ( e . g . parthenium spp . plant material ) in a molten thermoplastic to produce a homogeneous material . various additives are added and moisture is removed during compounding . compounding may be accomplished using either batch mixers ( for example , internal and thermokinetic mixers ) or continuous mixers ( for example , extruders and kneaders ). batch systems allow closer control of residence time , shear , and temperature than do continuous systems . batch systems are also more appropriate for operations consisting of short runs and frequent change of materials . on the other hand , continuous systems are less operator - dependent than are batch systems and have less batch - to - batch differences ( anon . 1997 ). the compounded material can be immediately pressed or shaped into an end product while still in its molten state or pelletized into small , regular pellets for future reheating and forming . the most common types of product - forming methods for fiber - thermoplastic composites involve forcing molten material through a die ( sheet or profile extrusion ) into a cold mold ( injection molding ) or pressing in calenders ( calendering ) or between mold halves ( thermoforming and compression molding ). fiberboard and particleboard - thermoplastic composites can also be made using standard forming techniques ( suchsland , o . and woodson , g ., 1986 . dry - process fiberboard manufacture . fiberboard manufacturing practices in the united states , usda forest service agriculture handbook no . 640 , pp . 136 - 167 ; usda forest service agricultural handbook no . 72 , wood handbook : wood as an engineering material , prepared by the forest product laboratory , forest service usda , pp . 22 - 1 to 22 - 13 ; usda forest service agricultural handbook : wood - based composites and panel products , wood handbook : wood as an engineering material , prepared by the forest products laboratory , forest service usda , general technical report fpl - gtr - 113 , pp . 10 - 1 to 10 - 31 ). properties of plant fiber - plastic composites can vary greatly depending upon such variables as type , form , and weight fractions of constituents , types of additives , and processing history . composites with high thermoplastic content are not without tradeoffs . impact resistance of such composites decreases compared with that of unfilled thermoplastics , and these composites are also more sensitive to moisture than unfilled material or composites filled with inorganic material . from a practical standpoint , however , the thermoplastic component usually makes the temperature sensitivity of the composite more significant than any change in properties brought about by moisture absorption . composites with low thermoplastic content can be made in a variety of ways . in the simplest form , the thermoplastic component acts much the same way as a thermosetting resin ; that is , as an adhesive to the plant material component . an alternative is to use the thermoplastic in the form of a textile fiber . the thermoplastic textile fiber enables a variety of plant materials to be incorporated into a low - density , nonwoven , textile - like mat . the mat may be a product in itself , or it may be consolidated into a high - density product . experimentally , low - thermoplastic - content composites have been made that are very similar to conventional plant material composites in many performance characteristics ( youngquist et al ., 1994 ). in their simplest form , plant particles or fibers can be dry - blended with thermoplastic granules , flakes , or fibers and pressed into panel products . because the thermoplastic component remains molten when hot , different pressing strategies must be used than when thermosetting adhesives are used . two options have been developed to accommodate these types of composites . in the first , the material is placed in the hot press at ambient temperature . the press then closes and consolidates the material , and heat is transferred through conduction to melt the thermoplastic component , which flows around the plant material component . the press is then cooled , “ solidifying ” the thermoplastic so that the composite can be removed from the press . alternatively , the material can be first heated in an oven or hot press . the hot material is then transferred to a cool press where it is quickly consolidated and cooled to make a rigid panel . some commercial nonstructural plant material - thermoplastic composites are made in this way . in contrast to high - thermoplastic - content and conventional low - thermoplastic - content composites , nonwoven textile - type composites typically require long fibrous materials for their manufacture . these fibers might be treated natural materials like jute or kenaf , but more typically they are synthetic thermoplastic materials . nonwoven processes allow and tolerate a wider range of plant materials and synthetic fibers , depending on product applications . after the fibers are dry - blended , they are air - laid into a continuous , loosely consolidated mat . the mat is then passed through a secondary operation in which the fibers are mechanically entangled or otherwise bonded together . this low - density mat may be a product in itself , or the mat may be shaped and densified in a thermoforming step ( youngquist et al ., 1994 ). if left at a low density and used without significant modification by post - processing , the mats have a bulk density of 50 to 250 kg / m 3 ( 3 to 16 lb / ft 3 ). these products are particularly well known in the consumer products industry , where nonwoven technology is used to make a variety of absorbent personal care products , wipes , and other disposable items . the products are made from high - quality pulps in conjunction with additives to increase absorptive properties . a much wider variety of plant materials can be used for other applications , as described in the following text . one interesting application for low - density nonwoven mats is for use as insulation . low - density mats can also be used for air or paint filters . the density can be varied , depending on the material being filtered and the volume of material that passes through the mat per unit of time . high - density fiber mats can be defined as composites that are made using the nonwoven mat process and then formed into rigid shapes by heat and pressure . to ensure good bonding , the plant material can be precoated with a thermosetting resin such as phenol - formaldehyde , or it can be blended with synthetic fibers , thermoplastic granules , or any combination of these materials . high - density fiber mats can typically be pressed into products having a specific gravity of 0 . 60 to 1 . 40 . after thermoforming , the products possess good temperature resistance . because longer fibers are used , these products exhibit better mechanical properties than those obtained with high - thermoplastic - content composites ; however , the high plant material content leads to increased moisture sensitivity . guayule , in whole - plant form , bagasse ( after the water - based extraction of latex from the whole plant ), and limbs , for example , can be converted into a fiber or particle form that can then be used to fabricate medium density fiberboard ( mdf ) or particle panels . the plants are reduced to chip form in a hammermill , and then are defibrated , for example , in a sprout bauer 305 mm thermal mechanical single disk refiner . defibration is done in a batch process with each batch limited to a maximum of 4 kg by the capacity of the receiver tank . before refining , the chips are poured into a digester , ahead of the refiner , to soften them to obtain a higher quality fiber . the chips going into the digester are held for 20 minutes under 586 kpa of steam pressure . defibration occurs as the chip passes between the rotating and stationary plates of the refiner . a description of how these panels can be fabricated is presented in the following text . the d2b503 type of sprout - bauer refiner plates with periphery surface dams enclosed are used for the refining process ; the plate gap is 0 . 36 mm . refining each batch takes approximately 4 minutes , generaly running between 3 min , 45 sec to 4 min , 10 sec . the physical characteristics of the fiber can be controlled or modified by varying the chip retention time within the digester , varying the gap between the refiner plates and through the selection of the refiner plate patterns . the thermosetting adhesive used , for example , can be a water - soluble , liquid urea formaldehyde resin obtained from neste resins corporation , north bay , ontario , canada . the resin , ba - 255 , has a solids content of 65 percent , viscosity of 0 . 19 cps at 25 ° c ., ph of 7 . 62 , and specific gravity of 1 . 281 . when defibration is finished , the resultant fibers have an approximate moisture content of 125 percent . the fibers are dried before further processing . the drying process is done in a steam - heated tray dryer at 94 ° c . for 24 hours . the fibers are dried to a final moisture content of 3 to 4 percent . the drying process causes the fibers to clump together due to hydrogen bonding and is not suitable for use without further processing . the oven - dried fibers are processed through a hammermill using a 19 mm screen opening . the purpose of the hammermilling process is to break - up the clumps and not to shorten fiber length . this procedure results in a high quality fiber with few noticeable fines . the urea - formaldehyde adhesive is mixed together using a high - speed laboratory mixer . the adhesive mixture is sprayed onto the natural plant fiber at 25 ° c . as it rotates in a drum type blender . all of the blended adhesive coated natural fibers are then hammermilled again . the purpose of the hammermilling process in this case is to break up balls of fiber formed by the resin spraying step . the same 19 mm hammermill screen opening is used with this process . mats are hand - formed in a 508 mm by 508 mm deckle box , which is attached to a vacuum . the adhesive coated natural plant fiber is forced through a 6 mm screen on the top of the box . this is done by hand using a brushing motion . this allows individual fibers and fiber bundles to pass through the top screen and collect at the bottom of the box . when all the fiber has been put into the deckle box , the mats are manually pre - compressed . depending on the target thickness of the board , the average height of the formed mat is 203 mm to 356 mm . in order to reduce the mat height and to increase its density it , the mat is then cold pressed . this procedure reduced the mat height to about 127 mm to 152 mm , which allows for easy insertion into the hot press . particleboard panel products typically are made from small plant particles and flakes that are bonded together with a synthetic adhesive under heat and pressure . the procedures for forming particle and flake mats are similar to those described above for making fiberboard mats . for both types of boards , all panels are consolidated using a manually controlled , steam - heated press . the press temperature is either 170 or 190 ° c . maximum panel pressure during closing is in the range of 3 . 05 to 6 . 10 mpa and reduced to 0 . 11 mpa after reaching the target thickness . all panels are made with a thermocouple inserted into the center of the formed mat to insure that the core temperature reached optimum levels for proper resin cure . for the 6 mm panels , a press temperature of 190 ° c . is used to bring the mat core temperature to 110 ° c . as quickly as possible . when 110 ° c . is reached , a brief de - gas cycle is used to reduce the steam pressure in the panel . total press time is 5 minutes . the press temperature may be reduced to 170 ° c ., and the total pressing time may be reduced from 5 to 4 minutes for the 13 mm panels . the de - gas cycle maybe eliminated by very careful opening of the press at the end of the pressing cycle . various pressing protocols may be used depending upon the panel thickness being produced . mechanical and physical property tests are conducted on specimens cut from the selected experimental panels . for all thicknesses , each panel is weighed , measured and the specific gravity is calculated . panels , from which the test specimens come , are selected on the basis of which ones are closest to the target specific gravity of 0 . 77 ± 0 . 05 and the target thickness . this method of the panel selection allows for narrowing the variability in specific gravity between individual experimental panels . prior to mechanical and physical property testing , the specimens are conditioned at 50 percent relative humidity and 20 ° c . three - point static bending modulus of rupture ( mor ) and modulus of elasticity ( moe ), and internal bond strength ( ib ) tests are performed in conformance with astm d1037 standards ( 1999 a ) using an instron testing machine . thickness swell and water absorption measurements are made by immersing specimens in water in a horizontal position for 24 hours at ambient temperature . this test is performed in conformance with astm d1037 . linear expansion tests are conducted on length measurements made at equilibrium conditions at 50 and 90 percent relative humidity , and at 27 ° c . the linear expansion test was done in conformance with astm d1037 . guayule ( parthenium argentatum ) is only one of the many species comprising the entire genus of parthenium . the outstanding feature of the p . argentatum species , which includes guayule , is that guayule is the only one that synthesizes high molecular weight rubber molecules . the guayule latex is hypoallergenic and has been used to make medical products , i . e ., gloves , balloons , catheters , etc . in addition to rubber , guayule also makes resinous materials . the resin has been reported to exhibit anti - termitic and anti - fungal properties ( bultman et al ., 1991 ; gutierrez et al ., 1999 ). other parthenium species also synthesize resin material similar to that of guayule ( rodriguez , e . 1975 . the chemistry and distribution of sesquiterpene lactones and flavonoids in parthenium ( compositae ): systematic and ecological implications . unpublished phd . thesis . umi , ann arbor , mich .). studies to test resins from other species for their biocontrol properties is lacking . guayule is the species of choice to work with for the resinous material because the plant has the potential to be cultivated for its latex . large amounts of waste material will result following the extraction of latex . only about 3 to 5 % ( w / w ) of the plant is generally used for making latex . the rest must be disposed . conversely , guayule may be cultivated for its resin with the latex then being considered the by - product . there are approximately 30 varieties or lines of guayule are in the usda collection ( hammond , b . l . and polhamus , l . g . 1965 . research on guayule ( parthenium argentatum )): 1942 - 1959 . usda tech . bulletin no . 1327 . 157 pp .). guayule varieties designated as n565 and 11591 are of particular interest because of their uniformity . bultman et al . ( 1991 ) used the resin extracted from another variety , the gila - 1 ( now designated as az - 101 ), in his studies on anti - termitic and - fungal studies . this variety was obtained from the rubber extraction facility operated by department of defense ( dod ). the az - 101 variety is a cross or hybrid between parthenium tomentosum and p . argentatum , variety 11591 . p . tomentosum has very little rubber , and mostly resin . the dod contractor selected the az - 101 hybrid because of its large biomass and good growth characteristics , even though the rubber content was not as high as other available usda varieties . in contrast , az - 101 had higher resin contents than the usda lines . composites composed of parthenium spp . plant material and plastic were prepared from whole plant or bagasse and high density polyethylene ( hdpe ) or phenol formaldehyde ( pf ) plastic . the experimental composite particleboards were made from ground plant material without any binder . composite boards were made from the ground plant material using commercial thermal - setting liquid phenol formaldehyde ( pf ) synthetic adhesive or a high - density polyethylene ( hdpe ) powder . the ground plant material was mixed thoroughly with the plastic and the composite formed by the melt - blending procedure at approximately 5 . 04 mpa and 177 ° c . the pf content of the composite was 6 %; the hdpe content was 30 %. three species of parthenium , ( a ) argentatum ( commonly called guayule ), ( b ) incanum and ( c ) tomentosum were used . for purposes of comparison to the composites of the invention , natural guayule resin - treated wood was prepared using southern yellow pine ( pinus spp .). the guayule resin was obtained by acetone extraction of guayule material . for the resin treatment , wood blocks were placed into a pressure chamber , and the system evacuated until maximum vacuum was attained . the acetone - guayule resin solution was then introduced at various concentrations to fill the chamber . pressure using nitrogen gas was applied at 700 kpa for 30 min . after the impregnation treatment , the wood was oven - dried at 60 ° c . to remove the volatile acetone solvent . termite resistance tests for the wood materials were run for one week , essentially following astm d - 3345 ( astm 1999b ) using the eastern subterranean termite reticulitermes spp . at an exposure of 7 days . fungal decay resistant tests for the treated wood blocks were run according to astm method d - 2017 ( astm 1999c ). the two common brown - rot fungi : gleophyllum trabeum ( atcc 11539 ) and poria placenta ( fr .) cook ( atcc 11538 ) were used . the samples were exposed to the fungi for 65 to 80 days . measurements of the blocks were made after the samples were dried . duplicates were run for each treatment combination . the guayule composite board with 30 % hdpe controlled 100 % of the termites within a seven - day exposure . only 30 % of the termites were alive with the guayule particle board alone , with no plastic adhesive . parts of the whole plant ( branches ) were also able to control termites . this was not reported before in the literature . the composite board made tip of guayule plant material containing 10 % natural resin was superior to the wood treated to 97 % with the extracted resin ( table 1 ). similarly , guayule particle board had similar anti - termitic properties as the wood impregnated to contain 51 . 8 % extracted resin . thus , fabricating guayule composite would be preferred to making anti - termitic wood instead of by impregnating it with guayule resin . the composite wood made from the three species of parthenium , e . g ., argentatum , tomentosom , and incanum all showed anti - termitic properties ( table 2 ). other species of parthenium could show similar anti - termitic properties when made into composites . composite made from southern pine did not show as much termite control as the partheniums and the pine wood alone had no resistance to termites . the composites of p . argentatum whole plant and bagasse , where the latex has been removed , both show similar anti - termitic properties . because bagasse is the waste plant material from the latex extraction process , it would be a preferred economical source rather than using the whole plant . the anti - fungal property of the guayule composite is demonstrated in table 3 . similarly to the anti - termitic properties , the composite board showed better anti - fungal resistance than the resin - impregnated wood . in this case , the 30 % hdpe - guayule composite had similar resistance as the wood impregnated with 51 . 8 % resin . thus , it is highly advantageous to fabricate composite boards with anti - fungal resistance than make the resin - impregnated wood as demonstrated by bultman et al . ( 1991 ). american society for testing and materials ( astm ). 1999b . standard test method for laboratory evaluation of wood and other cellulosic materials for resistance to termite . d - 3345 - 74 ( re - approved 1992 ). book of astm standard . sect . 4 , vol . 04 . 10 - wood . astm . west conshohocken , pa . american society of testing and materials ( astm ). 1999c . standard test method for accelerated laboratory test of natural decay resistance of woods . d - 2017 - 81 . astm . west conshohocken , pa . bultman , j . d ., gilbertson , r . k ., adaskaveg , j ., amburgey , t . l ., parikh , s . v ., and bailey , c . a . 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