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End grain sealants for wood preservation studies
1985 - IRG/WP 3341
The results of tests with possible end grain sealants for wood preservation studies are reported. The epoxy resins used gave satisfactory performance on wet or dry Sitka spruce and have been used with success for diffusion treatment studies.
R J Murphy, N A Summers

Radical changes in the requirements for more safe pressure impregnation in the Nordic countries in 1988
1990 - IRG/WP 3581
After introduction of quality control schemes and standards in the Nordic countries during the seventies, the first radical change of the standards and practice of work took place after pressure from the labor unions and authorities in 1988 and 1989 in Denmark and in Sweden. A new class of preservation with less retention for out of ground contact use was introduced, fixation times were prolonged to 6 and 14 days, and branding became a requirement. At the same time, treating companies replaced CCA with arsenic-free preservatives, and started using processes for accelerated fixation. Drying of treated wood was started to be used widely.
B Moldrup

Effectiveness and synergistic effects between copper and polymer betaine
1996 - IRG/WP 96-30097
Different formulations of "Copper Amine" and Polymer Betaine were studied. During laboratory tests a synergism between both active ingredients against soft rot and dry rot has been found. The efficacy against soft rot according to the "BAM method" and the European Standard ENV 807 depends only on the amount of copper. Long term tests in a fungus cellar for determining the relative protective effectiveness in ground contact show similar results as CCA-treated wood.
H Härtner, V Barth

Fluoride woodpill
1987 - IRG/WP 3431
Decay problems of spruce joinery in the Netherlands in the 1960's and 1970's led to the introduction of preservative treatment. Because of the known penetration difficulties with Spruce, the results of the treatments were not always successful. The fact that the decay was found only in the joints led to development of the philosophy of "local preservation" of the joints in remedial and preventative treatments, like preservative injections or use of rods and capsules containing preservatives. However the diffusion of the preservatives used in most of these systems is often poor in spruce. Because Spruce joinery dip-treated with bifluorides showed good penetration and protection, a pill consisting of a hydrophylic polymer and bifluorides was developed by TNO. Various laboratory tests carried out with this pill have confirmed good penetration of the bifluorides in the wood and activity against decay fungi.
J W P T Van der Drift, K J M Bonsen

Biosynthesis of ß-Glucan microfibrils by cellular fractions from brown-rot fungus Postia placenta (MAD-698 and ME-20) and white-rot fungus Schizophyllum commune (MAD-619)
1993 - IRG/WP 93-10025
In this study, we compared the brown rot fungus Postia placenta (MAD-698 and ME-20) with the white rot fungus Schizophyllum commune (MAD-619) to determine the location and distribution of glucan synthetase. We also measured the soluble protein content in subcellular fractions obtained by differential centrifugation MAD-698 is a degradative isolate, but ME-20 and MAD-619 do not produce significant weight loss in wood. The solubilized enzyme glucan synthetase catalyzes the UDP [U-l4C] glucose to synthesize an insoluble linear 1,3-ß-D-glucan polymer. Glucan is a component of basidiomycete cell walls and hyphal sheath. The wood-degrader MAD-698 showed the most glucan synthetase activity in the mixed membrane fractions, and the nondegradative isolates ME-20 and MAD-619 had the most activity in the cytoplasmic fractions. In fact, glucan synthetase activity was found in different proportions in different particulate fractions of MAD-698, ME-20, and MAD-619. Treatment with a mixture of the detergents octylglucoside and CHAPS ( 3 -[(3-Cholamidopropyl)-dimethylammonio]-1-propane-sulfonate) increased the glucan synthetase activity only in the cell wall fraction.
S C Croan, T L Highley

The Effect of Heat on the Retention of Ammoniacal Copper Quat (ACQ-AB) onto Scots Pine (Pinus Sylvestris L.) Wood
2008 - IRG/WP 08-40390
In this study, the sapwood of Scots pine (Pinus sylvestris L.) were treated with ammonical copper quat type (ACQ-AB), which is one of the environmentally friendly wood preservatives, by using soaking method as a functions of various temperatures and time. The results indicated that the retention behaviour of ACQ onto the wood was considerably affected by temperature of ACQ solution and treatment time.
M Hakki Alma, A Mukremin Kara

Low polymer levels containing bioactive monomer polymerized in situ provide resistance to Gloeophyllum trabeum
1995 - IRG/WP 95-30066
Wood preservation based on in situ polymerization of potentially bioactive monomers has been studied. Tributyltin oxide acrylate (TBTOA) and pentachlorophenol acrylate (PCPA) were synthesized. Wood samples were treated at 2, 5, 10, 15 and 20% by weight solutions with varying amounts of crosslinker (trimethylolpropane trimethacrylate, TMPTM) and polymerized in situ in wood samples (2.54 x 2.54 x 0.635 cm³). Methyl methacrylate (MMA) also was run at the same concentrations as a non-bioactive monomer comparison. Soil block testing was performed on acetone leached samples using Gloeophyllum trabeum in a standard ASTM test for 12 weeks. TBTOA was effective at all levels except when using greater than or equal to 10% crosslinker concentrations. PCPA showed some efficacy with 0% crosslinker present, but otherwise it gave no more protection than the MMA controls alone. This is probably due to the stable ester linkage formed in the polymer. Further investigation is underway to synthesize and biologically evaluate new bioactive monomers at low polymer levels for wood protection.
R E Ibach, R M Rowell

Quality of timber impregnated with preservatives of class AB after three years in service
2002 - IRG/WP 02-20241
Quality of impregnated timber is most often expressed by penetration and retention of the preservative used. Relatively less information is available about the performance of the final product, e.g. decks, panels etc. regarding product’s surface checks, deformations and overall appearance. Together with the timber durability, the above mention features are of esthetical importance in the above ground performance of timber. A comprehensive Nordic project dealing with pre-treatment, impregnation, durability and performance of Scots pine timber impregnated with copper-based preservatives for above ground use (class AB) was recently finished. The results from an above ground trail concerning the quality of timber are presented. The timber was dried in a conventional progressive, batch and high temperature kiln prior to impregnation. A significantly better quality regarding checks, deformations and deviation of the final moisture content, was achieved after conventional batch and high temperature dryings. Three preservatives (Kemwood ACQ 1900, Tanalith E and Wolmanit CX-8) were impregnated. The high temperature drying ensured the best penetration of all preservatives, but the retention was lower compared to conventional progressive and batch kiln dried timber. A part of the planks were conventionally kiln dried after the impregnation, the second part was air dried. Two decks with planks covering the variations in primary drying and preservative used were exposed; the former deck was in the open, the later one was under a shelter. After three years in service the planks were assessed regarding checks, deformations and moisture content. All three preservatives showed satisfactory appearance and no indication of decay was found. The deformations were comparable to those measured directly after final drying; the type of exposure had effect on the checks and moisture content of timber.
N Terziev

Physical and mechanical properties of wood-polymer composites prepared from alder wood (Alnus glutinosa (l.) gaertn. subsp. barbata (c.a.mey.) yalt)
2001 - IRG/WP 01-40201
In this study, the physical mechanical properties of wood-polymer composites prepared from alder (Alnus glutinosa (L.) Gaertn. subsp. barbata (C.A.Mey.) Yalt) wood were investigated. Three different monomers styrene, methyl methacrylate and styrene/methyl methacrylate (70/30) mixtures and two loading levels were used in preparation of wood-polymer composites. Of physical properties, the oven-dry specific gravity, the ratio of water uptake, the water repellent effectiveness and from mechanical properties; the compression strength parallel to the grain were determined. Full loading applications gave the best results for all monomer. The oven dry specific gravity, the water repellent effectiveness and, the compression strength parallel to the grain were found between 0.710-0.950 gr/cm3, 39.45-85.78% and 338.78-645.13 kp/cm2 respectively.
A Temiz, Ü C Yildiz, E D Gezer

On the resistance of consolidated ancient wood against Serpula lacrymans (Wulfen: Fr.) Schroeter
2000 - IRG/WP 00-10348
Structural timbers and other wood objects of cultural value in historical buildings and museums are often attacked by wood-destroying fungi. The aim of conservators is to preserve such damaged timbers and prevent further biodeterioration by impregnation with consolidants. There is little knowledge of the resistance of consolidated timber and art objects to a new attack by wood-destroying fungi. Brown-rotted wood consolidated with acrylic resins, PVA (poly(vinyl acetate)), epoxy resins, shellac, linseed oil, animal glue and a beeswax/paraffin mixture were tested against the brown-rot fungus, Serpula lacrymans. Specimens impregnated with linseed oil and the epoxy resins Araldit BY and Araldit DY did not show noticable mass loss. This was attributed to a high mass gain and even distribution of the consolidants. In contrast, specimens prepared with the acrylic resins Plexigum P-28 and Paraloid B-72 showed approximately 25% mass loss at a mass gain up to 40% because of uneven distribution in the wood. Decreases in mass loss were not proportional to increasing polymer loadings.
W Unger, A Unger, U Schiessl

The efficacy of polymer/preservative treatments in soil-bed exposure
1992 - IRG/WP 92-3729
Southern pine was treated with CCA, CCB, sodium borax/boric acid, or disodiumoctaborate, alone or in combination with an acrylic polymer system containing a water repellent. Treated samples were subjected to an unsterile soil burial test. The addition of polymer reduced the weight loss in borontreated samples at the lower retentions but not at the higher retention. Results with borates indicate that polymers may improve performance in above-ground applications. Polymer treatments improved the performance of CCA and CCB at retentions below threshold, indicating the potential for modifying CCA/CCB formulations.
R J Murphy, H M Barnes, S M Gray

New principles for the protection of wood: Impregnation with waterborne resins
1995 - IRG/WP 95-40047
The environmental impact of classical wood preservatives as well as the use of tropical wood species with high natural durability is regarded increasingly critically in the public. Therefore other partially new principles for the protection of wood, like chemical modification, or treatment with resins were examined especially in USA, Japan and in Europe with promising results predominantly in the lab scale. The work to be presented is focused on the feasibility to upgrade wood by a wide spectrum of water-borne resins under practical conditions of processing. The chemicals examined range from purely physically effective resins by hydrophobation and mechanical blockage up to such promising a chemical modification by their reactive groups. The behaviour of the resin solutions in a pressure process as well as the penetration parallel and orthogonal to the grain were investigated. Further, resin-uptake, improvement of hardness, and dimension stability, were examined. SEM studies are intended to show penetration pathways and linkage of the resins to the cell wall. Running tests on the investigation of the resistance against basidiomycetes and softrot fungi are not yet completed.
A O Rapp, R-D Peek

The effects of preservative treatment and exposure to wood degrading fungi on fiber reinforced polymer (FRP) materials used for structural wood reinforcement
2001 - IRG/WP 01-40204
Glass fiber reinforced phenolic (GFRP) composite materials are becoming increasingly accepted for use in the construction industry because they combine advantages of both wood and advanced polymeric materials. Addition of only 1-3% FRP in the tension zone, for example, can typically improve the strength of the hybrid system by 200%. As more applications are found for wood/FRP hybrids, (e.g. laminated wood for bridge applications, waterfront piers) their use in exterior and high-decay-hazard environments would be expected to grow. Since FRPs were designed to be used with wood material for use in exterior exposures, they will be exposed wood preservative chemicals, and to wood decay fungi as well. Therefore, currently developed glass-fiber reinforced phenolic polymer materials for wood reinforcement were examined to determine the effects of wood preservative chemicals and exposure to wood degrading fungi. Several common wood preservative chemicals (oil-and water-borne) were used for treatment of FRP materials. While chemically "fixing" preservatives resulted in significant strength loss, oil-borne preservatives systems did not affect the mechanical properties of the FRP material. When the common brown and white rot fungi (Gloeophyllum trabeum and Trametes versicolor) were used for fungal exposure studies, after 24 weeks of exposure G. trabeum exposed FRP coupons showed reduction in interlaminar shear strength. Scanning electron microscopy (SEM) and fluorescent photomicrograph 58 analysis supported the mechanical test results, indicating that fungal growth and possible consumption of organic sizing material on the wood/fiber interface had occurred. Further studies are underway with different organisms to provide a more detailed explanation of biodegradation mechanisms of FRP composites for wood reinforcement.
C Tascioglu, B Goodell

Effect of aqueous polymer treatments on wood properties. Part 2: Mechanical properties
1990 - IRG/WP 3611
Partially air-dried sapwood of sweetgum (Liquidambar styraciflua) and southern pine (Pinus spp.) was treated with either aqueous polyacrylate or aqueous dimethyloldihydroxyethyleneurea (DMDHEU) solutions. Tests for static bending, toughness, and hardness were conducted on matched treated and untreated pieces according to ASTM Standards. Properties of pine were not affected by treatment with the polyacrylate. With sweetgum, the modulus of rupture and modulus of elasticity were reduced, while hardness was improved. For the DMDHEU treatment, reduction in property values for both species was related to curing temperature.
Z Ashaari, H M Barnes, D E Lyon, R C Vasishth, D D Nicholas

The durability of wood polymer composites against fungi and insects
2000 - IRG/WP 00-40161
New materials such as wood polymer composites are used more in France. These materials are obtained by mixing wood and thermoplastics in different ratios. These kind of material must be considered as new materials and some characteristics such as durability must be evaluated for outdoor applications. On the other hand, some recycled fibers from wood waste could be used as raw materials. Some woodpolymers have been made in order to prepare some profiles by extrusion process. The wood species used as reinforced materials are beech, spruce, jaboty and limba. The thermoplastics used are recycled polyvinylchloride, polyvinylchloride and polypropylene. The mechanical and physico-chemical properties of some profiles have been characterised. The durability of these wood polymer composites has been evaluated. Significant results on durability against wood-decaying fungi and insects as termites are presented.
G Labat, I Le Bayon, J Gerard, F Amin

End grain sealing by polymer impregnation
1992 - IRG/WP 92-3708
The solution and dispersion characteristics of several hydrophobic derivatives of cellulose have been studied and the abilities of these polymers to afford effective end grain sealing of Corsican pine have been examined. Both solution and dispersion treatments with ethyl cellulose imparted good water repellency and end grain sealing to wood samples, however, the disperse systems possessed lower viscosities. Scanning Electron Microscopy (SEM) of treated samples and polymer radiolabelling/autoradiography studies indicated pit-membrane pore filtration of polymer particles close to the end grain. A range of esters (C2-C18 side chains) of Hydroxypropyl Cellulose have been prepared and characterised (FTIR, NMR). The acetyl, propyl and butyl esters formed coherent, flexible films. The C6, C9, C10 and C11 esters were essentially gums. However, the C18 (stearoyl) ester was found to form strong, wax like films, due to pronounced ester side-chain interactions. A number of the polymers were applied to Corsican pine test samples. Water repellent ability was found to strongly parallel the ability of the derivatives to form coherent polymer films. The C18 (stearoyl) ester exhibited impressive end grain sealing; outperforming all other systems tested at equivalent application levels. This work indicates that hydrophobic polymers that readily form strong films from solution or dispersion afford enhanced end grain sealing as compared to materials that simply produce a hydrophobic effect.
J M Lawther, W B Banks, D G Anderson, J A Cornfield

Evaluation of wood preservatives for Nordic wood preservation class AB
2002 - IRG/WP 02-30297
In the Nordic countries there are restrictions in the use of wood preservatives based on chromium and arsenic. For above ground use, class AB according to the Nordic system, only copper based preservatives are allowed in Sweden. Thus several new preservatives, copper based or metal free are now used. They have been approved by the Nordic Wood Preservation Council after passing laboratory tests against pure cultures of basidiomycetes. Their long term effectiveness in practice is still in many cases unknown. To increase the knowledge about these new “class AB” preservatives a field trial was started in 1996 at SP Swedish National Testing and Research Institute and another one in 1998 at The Swedish University of Agricultural Sciences. Durability against wood destroying fungi, leaching of preservatives during exposure and loss off effect against basidiomycetes in pure cultures of brown rot fungi after exposure were tested. As references untreated Pinus sylvestris and CCA-treated wood were used. For the preservatives tested the leaching after 5 years was between 15 and 100 % of the original retention while the leaching from CCA was less than 15 % for copper, chromium and arsenic. The durability in ground exposure was very low for wood treated with metal free preservatives. The amount of copper in copper based preservatives has a great influence on the durability in field. In general, with a higher retention of copper, the better was the performance. Test of durability in pure cultures showed a dramatic loss of effect when samples have been exposed outdoor above ground for two years compared to samples maintained in a dark conditioning room.
M-L Edlund, J Jermer

Three-year field trials of polymeric formulations which provide a new basis for the invention and design of non-toxic wide-spectrum wood preservatives
1994 - IRG/WP 94-40029
Three types of non-toxic polymeric formulations invented using a new approach to wood preservation were challenged with termites and fungi in three-year ground-contact field trials in the sub-tropical climate of Natal. These formulations were copper soaps of carboxylic acid groups of unsaturated fatty acids of waxes and edible vegetable oils; of resin acids of rosin, and, of synthetic unsaturated polyester resins. The formulations self-polymerise within lumena of wood elements after pressure-impregnation and also co-react with carbon-carbon double bonds and aromatic nuclei of lignin. The biocidal mechanism is based on the release of copper by hydrolysis under humid conditions and on the reformation of the same bond on redrying of the treated timber in service. All formulations tested were effective and durable. Rosin formulations at retentions of 0.91 kg/m³ and polyester formulations at retentions as low as 0.4 kg/m³ each out-performed creosote at 37.5 kg/m³.
A A W Baecker, A Pizzi

Effect of aqueous polymer treatments on wood properties. Part 1: Treatability and dimensional stability
1990 - IRG/WP 3610
Partially air-dried sapwood of sweetgum (Liquidambar styraciflua) and southern pine (Pinus spp.) was treated with either aqueous polyacrylate or aqueous dimethyloldihydroxyethyleneurea (DMDHEU) solutions. Tests for dimensional stability were conducted on matched treated and untreated pieces. Measurement of the antishrink efficiency indicated that DMDHEU was a better stabilizer than the polyacrylate system. Stability was related to polymer retention and curing temperature.
Z Ashaari, H M Barnes, R C Vasishth, D D Nicholas, D E Lyon

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

The Development of a novel method to preserve reeds using an environmentally friendly timber preservative and a unique engineering design.
2006 - IRG/WP 06-40335
Reeds are used in the construction of bush lodges in Northern Kwa- Zulu Natal, South Africa. Fungal, insect and ultra-violet damage to these reeds is posing a severe problem. Within a space of two years, the reeds are attacked and have to be subsequently replaced; a time consuming and costly exercise. A novel method has been used to successfully preserve these reeds with an environmentally friendly preservative containing disodium octaborate tetrahydrate in a water-based polymer system. The polymer allows for uninhibited diffusion of boron into the reeds, whilst the polymer cures to form a continuous protective film. By making use of two strategically drilled holes, which are 2 mm in diameter, the preservative is introduced into the reed shafts and nodes. The boron successfully diffuses into the walls of the reeds and is prevented from leaching out of the reeds. The water-based polymer provides sufficient protection against excessive ultra-violet damage. The test site, which is situated in the Hluhluwe Game Reserve in Northern Kwa-Zulu Natal – South Africa, has been monitored for nearly two years and there are no sign of insect or fungal damage to the reeds. Over the two-year period, the reeds were periodically inspected for deterioration in colour and deterioration in structural integrity.
K Govender, K G Moodley

Moisture dynamics of WPC as basis for biological durability
2010 - IRG/WP 10-40520
The largest market for wood-polymer composites (WPCs) is currently decking. Although many products are commercially available, a proper standard for the assessment of the biological durability of WPC does not exist. Recommended standards for testing resistance against basidiomycetes should be completed with a method to bring the specimens in a worst case situation, obtaining a moisture level high enough to initiate and support fungal growth at the beginning of, or early in the test. In this study a simple, but efficient way to increase the moisture level of test specimens of 9 commercialized WPC decking products is presented. The 24 h air-drying period after 4 weeks immersion in warm water strongly reduced the high moisture content (MC) of the wood particles, but the induced thickness swell may allow a quicker re-moistening. Performing a fungal test with these moistened specimens, Coriolus versicolor caused 2 – 15% mass loss (ML) and Coniphora puteana 1 – 12% ML despite of the poor virulence of latter fungus. ML was correlated with the MC after incubation and the thickness swell due to the pre-treatment. The ability of fungal spores to settle on WPC surfaces was investigated as well by placing specimens in a cabinet loaded with mist saturated with fungal spores and an equivalent outdoor test setup. Linking results to the composition or production process is difficult and was not the main goal of this research, but PVC based materials clearly performed the worst: high water absorbing and thickness swell, the highest ML in lab-based fungal testing and the most distinct fungal staining during outdoor exposure.
N Defoirdt, J Van Acker, J Van den Bulcke

Characterization of wood modification prepared by in situ polymerization with pre-polymer and the mechanism of modification
2013 - IRG/WP 13-40633
Chemical modification of wood is a potential way to obtain high quality wood. In this study, the fast-growing poplar was impregnated with modifier using a pulse-dipping machine by in situ polymerization. Fungal decay analysis, mechanical properties and dimension stability of the natural and modified woods were investigated. The wood samples were also characterized by X-ray diffraction (XRD) Thermal stability (TG), fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray analyzer (EDXA) and scanning electron microscopy (SEM). The mechanism of in situ polymerization was presented in graphs. The test results showed that the mechanical properties and dimensional stability of natural wood were improved remarkably. The durability against fungus was examined and weight loss reached 6.16% after modification. XRD test showed that the crystallinity of wood increased after modification. Thermo-gravimetric (TG) analysis resulted that the thermal stability of the modified composites was improved. FTIR analysis suggested that the pre-polymer polymerized with the active groups of wood cell wall. Moreover, CP/MAS 13C NMR analysis revealed that the in situ polymerization between pre-polymer and the hydroxyl in wood structure took place, with the reduction of hydroxyl groups. The XPS analysis indicated that the content of carbon element decreased, while the content of oxygen element increased. Finally, the SEM analysis proved that the good interfacial adhesion of wood modifier between wood fiber and polymer.
Qian Lang, Zeng Bi, Junwen Pu

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