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Contribution to the testing of wood based board material
1982 - IRG/WP 2176
R G Lea


A Preliminary Report on the Properties of Engineered Wood Composite Panels Treated with Copper Naphthenate
2005 - IRG/WP 05-40294
This paper reports on our preliminary investigation of the properties of randomly oriented strandboard which had waterborne or powdered copper naphthenate (CuN) incorporated into the board during manufacture. When compared to zinc borate-treated controls (ZnB), the mechanical properties of strandboard (MOR, MOE, work-to-maximum load, internal bond strength) were not adversely affected by treatment with either form of copper naphthenate. In general, values for mechanical properties followed the trend untreated controls > waterborne CuN = powdered CuN > ZnB. Water absorption and dimensional properties followed a similar trend. This preliminary study suggests that CuN is a viable alternative treatment for engineered wood composites.
J W Kirkpatrick, H M Barnes


Worldwide in-ground stake test of acetylated composite boards
1997 - IRG/WP 97-40088
Acetylated wood composite stakes are being tested in ground contact (graveyard test) in seven fields around the world. Three types of acetylated wood composites were prepared: spruce fiberboard in Sweden, aspen fiberboard in Madison and rubber wood particle board in Indonesia. Two levels of acetylation were used, a high level of ~20% acetyl content and a low level of 10% acetyl content. Control boards of unmodified wood fiber/particle were also included. Stakes for the in-ground testing were taken from the boards and the size of each stake was 5x30x1.25 cm3. The stakes were put out in four continents: one test field in USA, one in New Zealand, two in Indonesia and three in Sweden. After three years of testing, results show that acetylation of wood provides excellent protection against fungal attack and minimizes swelling.
R M Rowell, B S Dawson, Y S Hadi, D D Nicholas, T Nilsson, D V Plackett, R Simonson, M Westin


Durability of Wood Plastic Composites Relative to Natural Weathering and Preservative Treatment With Zinc Borate
2005 - IRG/WP 05-40316
Wood-Plastic Composites (WPCs) used for decking have experienced dramatic increases in North America, averaging 25% growth per annum since 1998. A key factor contributing to this growth has been the successfully communicated message that they are "virtually maintenance free". The common perception being that the wood fiber is completely encapsulated by the thermoplastic resin, minimizing the potential for moisture absorption and inhibiting attack by wood destroying organisms. Recent publications, however, have raised concerns about the durability of WPCs. These studies showed that wood particles close to the surface of WPC products can attain moisture levels high enough to facilitate the onset of decay. Other experiments have shown that preconditioning this material through accelerated laboratory weathering (QUV) or natural exterior exposure to the elements, yielded significant increases in moisture uptake relative to the unexposed samples. The ability of these materials to absorb moisture has been identified as a significant factor in evaluating decay susceptibility in these laboratory tests. We examined moisture uptake in large sized (low surface to volume ratio) and smaller cut (high surface to volume ratio) WPC samples and found a much greater and rapid water uptake in the smaller samples. A soil block decay test with commercially produced unweathered WPC’s resulted in weight losses of between 10-20% (20-40% wood component) in as little as four months time. Effects of exterior weathering on moisture uptake showed increased moisture in samples taken from WPC boards in the field at various locations for 1 to 2 years. A soil block decay test with unweathered and naturally weathered WPCs showed significantly high weight loses in samples that had been in an outdoor exposure in Valencia, Ca for 2 years. Samples from the same exposure test that had been treated with 1.0 or 2.0 % zinc borate showed almost no weight loss.
M E Mankowski, F M Ascherl, M J Manning


Utilization of plasma treatments in the field of wood protection
2021 - IRG/WP 21-40912
Plasma treatments have been used for modification of surfaces of wood and wood-based materials for some decades and solutions were developed to apply it for wood protection. This contribution aims to present the background, introduce the available plasma technology, and to give an overview on the typical applications and benefits.
S Dahle, H Militz


Soil bed studies of the dimensional stability of composite products
1999 - IRG/WP 99-40134
The influence of boron and isocyanate resin on the dimensional stability of high moisture resistant particleboard was assessed after burial in a soil bed for one month. The samples were treated with two levels of a boron compound and coated in isocyanate resin. The samples were randomly placed in a fungal cellar in soils of two different water holding capacities. Weight differences and dimensional changes were measured after one month. The results suggest that there is a significant increase in weight and thickness swelling. Boron treatment prior to resin impregnation also appears to have assisted moisture absorption.
K M Filcock, P Vinden


Laboratory Evaluation of the Formosan Subterranean Termite Resistance of Borate-treated Rubberwood Chipboard
2004 - IRG/WP 04-30359
Both no-choice and two-choice 4-week AWPA laboratory tests were performed to evaluate the resistance of borate-treated rubberwood (Hevea brasiliensis) chipboard prepared from a commercial mill run, against the Formosan subterranean termite Coptotermes formosanus. Boric acid (technical granular) was incorporated into the boards during manufacture to achieve loadings of 1.0% or 1.1% boric acid equivalents (BAE). In the no-choice test, both the untreated chipboard and solid rubberwood controls sustained heavy termite attack (respective mean visual ratings of 4.6 and 2.7 on a 10-point AWPA scale), while the two retentions of borate-treated chipboard showed only light grazing (mean rating 9.2). The two-choice test demonstrated a preference of termites for solid rubberwood (mean rating 2.4) instead of untreated chipboard (rating 8.4), and for untreated (mean rating 8.4 and 8.8) instead of borate-treated (mean ratings 9.8 & 9) chipboards. Complete termite mortality in the presence of borate-treated chipboard in both laboratory tests demonstrates the toxicity of borates to Formosan subterranean termites.
A H H Wong, J K Grace


Applicability of supercritical carbon dioxide to the preservative treatment of wood-based composites
2001 - IRG/WP 01-40199
Treatability of five structural-use wood-based composites (medium density fiberboard, hardwood plywood, softwood plywood, particleboard and oriented strand board) was evaluated when supercritical (SC) carbon dioxide (CO2) was used as a carrier solvent. Treatments were conducted at three temperature 32 levels (25, 35 and 45°C) and two pressure levels [80 kgf/cm2 (7,845 kPa) and 120 kgf/cm2 (11,768 kPa)]. Although small changes in weight and thickness of the wood-based composites were caused by treatments with SC-CO2, all treated materials did not sustain any physical damage. These results suggest that the treatment conditions provided the immediate penetration of SC-CO2 into the wood-based composites without any critical pressure gradient between outer and inner zones. Strength properties of the treated wood-based composites significantly improved after treatments in most cases. In contrast, a remarkable drop in strength properties occurred in oriented strand board specimens. Further studies are underway to determine the optimum treatment conditions using biocides incorporated into the mixing or treating vessel.
M Muin, A Adachi, K Tsunoda


Mobility of zinc borate wood composite preservative
1997 - IRG/WP 97-30153
Zinc borate (ZB) is being used as an antifungal and insecticidal wood preservative for flake/strand-based composites. Data is reported on the laboratory and field leaching behavior of ZB when contained in apen flake composites. In general, the performance results correlate with leaching hazard. Although the boron in ZB is more resistant to depletion than in sodium borates, the ZB boron will deplete over time under severe leaching conditions. In climates and/or exposures with higher leaching hazard, more depletion and corresponding fungal/insect attack is observed. The zinc component of ZB is much more resistant to depletion, but does not contribute as much to the preservative efficacy. Some depletion data indicates that a "reservoir" effect can occur, where boron from regions with a high ZB loading diffuses into regions of the test specimen with low loadings due to depletion. The good level of performance under these test conditions continues to support the use of ZB in protected exterior wood composite applications.
P E Laks, M J Manning


Preservative treatment of wood-based composites with a mixture formulation of IPBC-silafluofen using supercritical carbon dioxide as a carrier gas
2003 - IRG/WP 03-40251
Wood-based composites treated with a mixture formulation of a fungicide, 3-iodo-2-propynyl butylcarbamate (IPBC) and a termiticide, silafluofen using supercritical carbon dioxide (SC-CO2) as a carrier solvent were tested for their resistance to decay and termite attack in the laboratory. The treatment solution was prepared by mixing both biocides (IPBC 10 + silafluofen 1) with a co-solvent, ethanol to have an identical ratio of each constituent in the commercial formulation for superficial treatment of wood. SC-CO2 treatments were conducted at 35oC/7.85 MPa, 35oC/9.81 MPa and 55oC/11.77 MPa with a direct introduction of the biocidal solution into the treatment vessel where specimens (210 x 30 mm x thickness) of medium density fiberboard, hardwood plywood, softwood plywood, particleboard and oriented strand board were placed. Laboratory tests were conducted with the treated materials according to Japanese standard methods. Results of laboratory tests indicated that the current treatment conditions significantly enhanced the resistance of the treated wood-based composites against fungal and termite attacks. Comparison with the results obtained for wood-based composites treated with an individual biocide showed that treatment with a mixture would not cause any negative effect to the efficacy of each biocide, although the amount of each constituent in a mixture formulation must be carefully decided to provide wood-based composites with a satisfactory performance against any biological degradation when SC-CO2 is used as a carrier solvent.
K Tsunoda, M Muin


Biological resistance of wood-based composites under protected, aboveground conditions
2005 - IRG/WP 05-20312
Five kinds of wood-based composites (density fiberboard=MDF, hardwood plywood=HP, softwood plywood =SP, particleboard=PB and aspen oriented strand board=OSB) were tested for their resistance against subterranean termites and decay under protected aboveground conditions. The exposure method was previously developed for evaluating performance of sill plates (dodai) in Japanese homes. Ten replicates (10 cm square x board thickness) were prepared from each wood-based composite, allocated into 5 groups so that two each were placed on a concrete block and covered with a PVC box to protect specimens from weather and to minimize site effect. Each specimen was placed on a 19 cm high concrete block with pine sapwood feeder stakes in the hollows of the concrete block. Annual visual inspection had been conducted and the degree of decay and termite attack was rated according to the AWPA standard (10: sound=no attack, 9: trace to slight attack, 7: moderate attack, 4:heavy attack, and 0: failure=no more available for further testing) since the specimens were installed in Kagoshima Prefecture, a southern part of Japan on June 22, 1999. As expected, biological attacks developed with time, although there was no sign of decay on any MDF, HP and PB specimen after 5 years’ exposure. Termites started attacking earlier and higher in terms of severity of damage than decay fungi. This was quite common to all wood-based composites tested. A few specimens showed unforeseen low or high resistance to biodeterioration: 4 SP and one OSB specimens rated 0 due to heavy termite attack. Performance of MDF was ranked first, and followed by HP, PB SP and OSB. These results suggest the necessity of protective treatment to ensure a longer service life of wood-based composites even for an aboveground use, as far as use conditions are considered to be conducive to biodeterioration.
K Tsunoda


Preliminary investigation on the natural durability of Guayule (Parthenium argentatum)-based wood products
2000 - IRG/WP 00-40154
Conventional preservatives used to protect wood from insect and microbial damages are presently of major concern to human health and the environment. Finding alternative and economical preservatives has not been successful. Previous studies have shown that the resinous material extracted from the guayule plant (Parthenium argentatum, Gray) has both insect- and microbial-resistant properties. Unfortunately, it has not been accepted commercially because of the lack of an adequate supply of the raw material. However, the potential domestication of the guayule plant to produce hypoallergenic rubber latex will result in the production of large amounts of waste wood material. This should provide opportunity to use this natural source of the biologically resistant resinous chemicals. The objective of this preliminary study was to determine the effects of the rubber latex-removed wood residues or bagasse and the resinous extracts on termite- and decay-resistant properties. Two types of test materials were used in the study. One was wood impregnated with organic-solvent extracted resinous material from the plant. The other was composite wood fabricated using the residue or whole plant and plastic binder, which was used to improve the physical properties of the composite. Accelerated laboratory tests were conducted to determine the resistance of the wood products against the Eastern subterranean termite and wood fungi (brown-rot). The wood and stem of the guayule plant, wood treated with the resinous extract, and particle and composite wood made from ground guayule exhibited termite and wood fungal resistance.
F S Nakayama, P Chow, D S Bajwa, J A Youngquist, J H Muehl, A M Krzysik


Effect of remediation on the release of copper, chromium, and arsenic from particleboard made from CCA treated wood
2001 - IRG/WP 01-50170
This study sought to determine the effect of remediation with oxalic acid (OA) extraction and Bacillus licheniformis fermentation on the release of copper, chromium, and arsenic from particleboard made from remediated wood particles and also investigates durability of the particleboard against white and brown- rot fungi. Particleboard samples were manufactured using untreated, CCA-treated, OA-extracted, and bioremediated southern yellow pine particles. Results shows that oxalic acid extraction and bioremediation by B. licheniformis significantly increased removal of elements from CCA-treated wood particles. The particleboards containing OA-extracted and bioremediated particles showed generally high leaching losses of remaining elements. Exposure of particleboard samples to decay fungi indicated that Gloeophyllum trabeum caused greater weight losses in all samples than Postia placenta. In general, leached samples from all particleboard types had greater weight losses than unleached samples. CCA particleboard samples were the most resistant to fungal degradation.
S N Kartal, C A Clausen


The effect of oil-borne preservative treatments on the shear strength of FRP/wood composite adhesive bonds
2003 - IRG/WP 03-40265
Reinforcement of structural wood components with Fiber Reinforced Polymer (FRP) will enhance the beam’s strength, but actual data on long-term durability is sparse, not well documented or not readily accessible. In this study, bond properties of FRP-wood composite materials were investigated following treatment with creosote or copper naphthenate preservatives. The properties investigated included stress and the percentage of wood failure experienced in shear (ASTM 1998). When tested in a wet condition (following a vacuum/pressure soak), creosote-treatment adversely affected the wood failure values associated with specimens fabricated with a pultruded FRP composite sheet (E-glass fiber, bonded with urethane). When these tests were conducted with samples under ambient conditions, the shear strength of this material was also adversely affected by creosote. In addition, both creosote- and copper napthenate-treatment adversely affected the shear strength of a SCRIMP™ fabricated FRP material (carbon fiber, vinyl ester matrix).
B Herzog, B Goodell, R Lopez-Anido


A new process for in situ polymerization of vinyl monomers in wood to delay boron leaching
1998 - IRG/WP 98-40110
Efforts were accelerated on effective use of boron compounds in wood preservation owing to their environmentally safe characteristics and relatively low costs in addition to their well-known high bioactivity and fire resistant properties. Although having these unique favorable properties, they are readily leachable from treated wood at humid conditions. Therefore, they had limited market for exterior applications. A supplementary combination treatment with vinyl monomers; styrene (ST) and methylmetacrylate (MMA) was studied in order to extend the service life of boron treated wood. Sapwood specimens of Japanese cedar (Cryptomeria japonica D. Don) first treated with boric acid (BA) at 1.00% aqueous solution concentration. Vinyl monomers were impregnated after air-drying of BA-treated wood at ambient temperatures. Polymerization was performed during compression of monomer impregnated wood to a 50 to 70% dry set of radial dimension under a hot-press heated to the polymerization temperatures of 60 and 90°C required by the selected catalysts VAZO (a, a' - Azobis-isobutyronitrile) and benzoyl peroxide, respectively. Wood acquired a perfect dimensional stability and remarkably high moisture exclusion efficiency with the minimum water holding capacity with the compressed-wood polymer composite (CWPC) process that was approved by submerging of the test specimens in tap water, boiling water exposure to a 10 cycles accelerated severe weathering. As a result, boron leaching rate from CWPC pretreated with BA was considerably slower than that from ordinary WPC. Scanning electron microscope (SEM) observations were found explanatory for controlled-but-continuous boron leaching determined analytically. An effective bulking was found necessary to accompany to polymerization in cell wall with an even distribution of monomer in wood. Grafting to cell wall components can be tried further to achieve an envelop polymerization of boron deposited sites in WPC for better boron immobility.
M K Yalinkilic, W Dwianto, Y Imamura, M Takahashi


Overview of European discussions on Standardisation and list of proposed standards for WPC performance qualification
2006 - IRG/WP 06-20345
The standardisation is a driving force to promote the development of Wood Polymer Composites (WPC) by giving confidence to users and consumers. In Europe, the high interest of WPC require at this time a diffusion of information concerning the performances of WPC products. The WPC performances must be assessed according relevant standards in order to qualify the intrinsic properties of WPC (mechanical properties, physical properties, durability, …). WPC processing and environmental aspects must be taken in account. A CEN/TC 249 WG 13 "Wood Plastics Composites (WPC)" have been created in 2005. In France, a French Standardisation committee BNPP/BNBA T54 W has been created in France in 2004, jointly by the BNPP (Bureau de Normalisation des Plastiques et de la Plasturgie) and the BNBA (Bureau de Normalisation du Bois et de l'Ameublement). A high interest of French companies from the two sectors have been observed. An overview of European discussions on Standardisation and list of proposed standards for WPC performance qualification are discussed. Following discussions in very at European level will be to define a list of suggested standards elaborated to qualify plastics and wood-based products and to propose relevant standards to qualify WPC. Current discussions are on going at this time in CEN/TC 249 WG13 and in French standadisation committee T54W to select and to propose change of the standards (ISO standards, EN standards and other document) in order to purpose test methods for characterisation of WPC material and products. Future works will be done in 2006 to validate these documents and to purpose standards.
G Labat, M Vernois, T Gay


Wood-Plastic Composites and the Durability Dilemma: Observations from the Field
2006 - IRG/WP 06-40351
Wood-Plastic Composites (WPCs) used for decking, window & door moldings have experienced dramatic growth in North America over the last several years, with annual production increasing at rates greater than 20% per annum since 1998. A key factor contributing to this growth has been the successfully communicated message that they are "virtually maintenance free". The common perception being that the wood fiber is encapsulated by the thermoplastic resin, minimizing the potential for moisture absorption and inhibiting attack by wood destroying organisms. A number of recent publications have raised concerns about the long-term durability of WPCs – in particular, when used in unprotected, above-ground applications. The fundamental question is whether or not the % Moisture Content (%MC) of the wood component can achieve the minimum level necessary to support fungal decay. Laboratory tests utilized by the WPC industry suggest this is not the case and yield values less than 10%MC - well below the accepted minimum threshold of 25% necessary to initiate and support fungal decay. This paper will describe work which evaluates the %MC of the wood component in WPC samples exposed in various field sites with different climatic Scheffer indices. These field results yield a dramatically different picture and show that the outer portion of the WPC surface can achieve %MC levels in the wood component which are in excess of the 25% threshold. Both macro and microscopic evaluations of untreated WPC material revealed evidence of fungal decay. The use of a preservative treatment such as zinc borate to protect against fungal decay will also be discussed.
M J Manning, F M Ascherl, M E Mankowski


Biological Protection of Composite Panel from Moulds and Decay
2007 - IRG/WP 07-10612
Composite panels, such as oriented strand board (OSB), are widely used in house construction in North America. These structural panels are normally made of non-durable wood species and are susceptible to moulds and decay when exposed to wet conditions. Building envelope failures due to moulds, decay or poor construction practices can negatively impact the image of wood. To ensure durability of composite panels, the most important consideration is the use of mould- and decay-resistant wood species to prevent fungal attack. Using low environmental impact technology to improve the durability of composite products could have market-related advantages over using chemical protection products. This research aimed to explore various potential biological treatments to protect composite panels from biodegradation, and to increase durability of panels for better resistance to mould and decay infection in service.
Dian-Qing Yang, Xiang-Ming Wang, Hui Wan


Performance of wood-based composites in a protected aboveground test in southern Japan
2008 - IRG/WP 08-40391
Five kinds of untreated wood-based composites (medium density fiberboard, hardwood plywood=HP, softwood plywood, particleboard and aspen oriented strand board, hereinafter abbreviated as MDF, HP, SP, PB and OSB, respectively) were exposed to subterranean termites and microbial (decay) attack under protected aboveground conditions in a southern part of Japan (Kagoshima Prefecture) for six years. Annual visual inspection was conducted and the degree of biological attacks was rated according to the AWPA standard since installation. As expected, both biological attacks generally developed with time. However, none of MDF, HP and PB specimens sustained decay attack even after six years’ exposure. Termites started attacking wood-based composites earlier and the severity of attack was higher than decay fungi. This was common to all tested wood-based composites in the current field evaluation. A few specimens showed low resistance to subterranean termites. The first failure was noticed on one of OSB and two SP samples after three years’ exposure due to delamination and/or destruction caused by termites. MDF performed best, and followed by HP, PB SP and OSB, although they were unexceptionally attacked by termites. These results suggest the necessity of protective treatment to ensure a longer service life of wood-based composites even for an aboveground use when it is supposed to be conducive to biodeterioration.
K Tsunoda


Wood plastic composites from modified wood. Part 3. Durability of WPCs with bioderived matrix
2008 - IRG/WP 08-40423
The decay resistance of fully bio-derived wood plastic composites, WPCs, was tested in both laboratory and field tests. The laboratory tests were performed according to modified versions of AWPA E10 (soil-block test) and ENV 807 (tests in three un-sterile soils) and the field tests according to EN 252 (stakes in ground) and EN 275 (resistance to marine borers). The WPC materials for laboratory tests were injection molded test specimens with 50% modified wood particles and 50% cellulose ester (CAP) or poly-lactic acid (PLA) content. The field test specimens were taken from larger extruded decking board profiles with 60% wood content and 40% CAP. 60/40-mix (wt/wt) for CAP corresponds to the same volumetric composition as 70/30-mix (wt/wt) with polypropylene as matrix that was presented in Part 1 and 2. In all laboratory tests the control WPCs performed much better than the pine sapwood control blocks. The WPCs from modified wood performed better than the control WPC and WPCs from acetylated wood performed best with no detectable decay whatsoever. In the field stake test, the WPC from unmodified wood were slightly decayed whereas the WPCs from modified wood were sound. In the marine field test the WPC from unmodified wood were severely attacked by shipworm (Teredo navalis), whereas the WPCs from modified wood were sound.
M Westin, P Larsson Brelid, B K Segerholm, M Van den Oever


Eco-Friendly Composites from Bagasse and Soy-based Resin
2009 - IRG/WP 09-40462
In this study, bagasse and soy-based resin were used for producing composite materials. The objective of this study was evaluation of some physical and mechanical properties of boards made of various ratios (100:0, 60:40, 40:60 and 0:100) of bagasse to wood fiber mixtures (wt: wt) with addition of Soy/PF resin at three levels (4, 8 and 10%) and 1.5% wax. All properties were tested according to ASTM D-1037 and all data were analyzed statistically. The results showed that by increasing bagasse fibers all properties of boards were deteriorated but by addition of 10% soy/PF resin all of them were improved significantly. Boards made of 40:60 ratio of bagasse to wood fiber mixtures and 10% Soy/PF resin content have acceptable bending strength and those are made of 100% bagasse and 10% Soy/PF resin content meet the requirements set for internal bond strength of the ANSI 208.2-1994 for interior uses.
G Rassam, B Jamnani


Progress in Fire-Retardant Research on Wood and Wood-Based Composites: a China Perspective
2009 - IRG/WP 09-40476
The fire retardant research on wood and wood-based composites, which was carried out in China in the past two decades, was reviewed with 55 references. While many kinds of fire retardants for wood and wood-based composites have been studied, the mainstream is still the compound or the mixture containing phosphorus, nitrogen and boron elements, which can be used in the form of water solution in the impregnation of solid wood. The fire-retardant treatment methods for wood panels are either pretreatment of veneers, fibres, particles and strands before hot pressing, or the impregnation of waterproof panels by fire-retardant solution. Though attempts have been done in lab to mix fire retardants with the glue, it has proved to be very difficult to spray glue with effective amount of fire retardants smoothly in the real manufacturing of fire-retardant panels. Fire retarding mechanism of phosphorus-nitrogen-boron fire retardants have been investigated systematically. The results indicated that for a proper fire-retardant formulation phosphorus-nitrogen compounds and boron compound are highly synergistic, that the catalytic charring effect of a fire retardant on wood is a key factor to its fire-retardant efficiency, and that a chemical fire-retardant mechanism for boric acid was proposed. The fire-retardant research on wood plastic composites has attracted more attention in recent years, however, most results are basically preliminary because of the difficulty for choosing or setting up a suitable fire retardant system that is effective to both of wood and plastics. Research on smoke suppression of wood was also discussed which was even more preliminary and innovative efforts are needed.
Wang Qingwen, Wang Fengqiang, Hu Yunchu, Li Jian


Lignin blocking effects on weathering process of wood plastic composites
2010 - IRG/WP 10-40529
The weathering of wood–plastic composites (WPC) causes discoloration which affects their aesthetic aspects. It has been proved that these discolorations are due to lignin degradation. Effects of blocking the susceptible structure of lignin assessed by chemical treatment such as acetylation and methylation are reported in this study. Surface chemical change of wood plastic composite (WPC) formulations based on high density polyethylene (HDPE) were monitored by means of ATR FT-IR spectroscopy and colorimetry. According to the standard ASTM 2565, samples were placed in Atlas Xenon apparatus for 250 hrs and 2000 hrs. The results have shown that methylation and acetylation can photostabilize lignin in short period of times. ATR FT-IR spectra shown that, in long term, none of the treatments could protect lignin degradation, within wood flour. Methylation limited the depth of penetration of weathering and these samples have more lignin content compared to control samples.
P Darabi, A Naghi karimi, S Ahmade Mirshokraie, M-F Thévenon


Optimization of oxalic acid production for bioleaching of metal components from CCA-treated wood by an unknown Polyporales sp. KUC8959
2010 - IRG/WP 10-50266
A brown-rot fungus, an unknown Polyporales sp. KUC8959, has recently been identified and proven as a prominent fungal species for bioremediation of CCA-treated wood wastes in our Lab. The fungus produced a larger amount of oxalic acid than other fungi tested, and removed 90 % or more of chromium, copper and arsenic from CCA-treated wood sawdust through bioleaching process. The bioleaching process was consisted of two steps comprising fermentation of the fungus for oxalic acid production and then extraction of metals by oxalic acid produced by the fungus. In order to maximize bioleaching efficiency, optimal fermentation conditions for oxalic acid production by the fungus is required. The objective of this study was to optimize oxalic acid production by unknown Polyporales sp. KUC8959. We used a 20-run central composite design (CCD) using response surface methodology (RSM) with three variables, that is, nutrient concentration, fungal biomass, and fermentation period. From the pre-cultured liquid fermentation broth, fungal hyphae were removed by filtering and then washed thoroughly with sterile deionized water. In accordance with the experimental design, fungal biomass (6.99, 18.32, 34.93, 51.55, or 62.88 mg) was inoculated in a flask containing 100 mL of malt extract solution (0.5, 1.11, 2, 2.89, or 3.5 %). Thereafter, the flask was agitated at 150 rpm on a rotary shaker at 27 °C for 48, 96.66, 168, 239.34, or 288 hours. From the fermentation broth, the amount of oxalic acid produced was determined by high performance liquid chromatography. The fitted RSM model investigated showed high regression coefficient between the variables and the response (R2=0.960) indicating that the model can be highly accurate in predicting the oxalic acid production at various conditions. The model suggested that optimum nutrient concentration, fungal biomass, and fermentation period were 2.40 %, 47.84 mg and 228.96 hours, respectively, to produce 4.11 g/L of oxalic acid. This fitted model will further be used for bioleaching of metals from CCA-treated wood.
Yong-Seok Choi, Min-Ji Kim, Jae-Jin Kim, Gyu-Hyeok Kim


Investigating extraction of bifenthrin from composite wood products
2011 - IRG/WP 11-20467
Bifenthrin is added to resin prior to lay-up of plywood and laminated veneer lumber to provide termite protection. Analysis of this chemical in resins can be challenging. The potential for using ground wood in place of sawn material to recover bifenthrin was investigated using laminated veneer lumber composed of Douglas-fir veneers analyzed by three laboratories. Although the results differed among the laboratories, bifenthrin recoveries were almost always higher from ground wood. The results suggest that this method could be modified to allow the use of ground wood if the target retentions were also increased. Other modifications to the standard that could improve bifenthrin recovery and the reproducibility of the method are also suggested.
J J Morrell, L Bell, J Norton, C Shaw


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