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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


Fluorine compounds for wood preservation
1971 - IRG/WP 304
Fluoride compounds have gained a considerable importance in wood preservation, especially in Germany and some other countries of Europe. They are used as single compounde or in mixtures of different compounds. In the International Research Group on Wood Preservation which continues the activities of a former OECD-Group, it was moved to prepare a survey on fluorides in wood preservation together with other papers on the present state of knowledge of wood preservatives and methods of application. Monofluorides and silicofluorides have been used in the field of wood preservation for about 60 years and special development and application of hydrogen fluorides have been going on for 30 years. Much scientific work has been carried out on fluorides and much experience in practical use is available. It thus seems to be useful to briefly summarise the information on this group of compounds in wood preservation. Due to the voluminous literature, ie some 270 papers which are cited in the references, only an introduction into the problems and main results but not a detailed review of the publications is possible. The subjects dealt with in the publications are indicated in the references. With some exceptions the brief survey is limited to the compounds and mixtures without chromium which remain leachable in the wood. Questions of toxicity to human beings, animals and plants are not discussed in this paper.
G Becker


Preliminary attempts towards the development of a small scale termite rearing chamber. Progress report
1983 - IRG/WP 1203
The results suggest that there is no evidence that the volume of the rearing chamber plays a part in the settlement of a colony. These rearing chambers present a factor of productivity (final enumeration)/(initial enumeration) of roughly 2 after one year. 90% of the colony survived. This method of breeding can be considered as feasible and cheap.
M Argoud, J C Palla, R Sternalsky


Iron in stone wool - one reason for the increased growth and decay capacity of Serpula lacrymans
1992 - IRG/WP 92-1537
The chemical compositions of stone wool and glass wool were analysed. There was more iron in the stone wool than in the glass wool. It was found that iron present in stone wool was easily dissolved by oxalic acid that Serpula lacrymans is able to produce. The stone wool promoted the decay of pine wood by Serpula lacrymans. The glass wool had no effect on the decay capacity of Serpula Iacrymans. The iron derived from the stone wool may be one reason for the increased growth and decay capacity of Serpula lacrymans. Transition metals (Fe2+, Mn2+, etc.) combined with hydrogen peroxide (H2O2) are believed to be necessary for the oxidative breakdown of polysaccharides.
L Paajanen, A-C Ritschkoff


Longterm monitoring of termite activity on multiple feeding sites: a laboratory method intended for the determination of attractant/repellent properties of wood preservatives and baits
2001 - IRG/WP 01-20225
A method is introduced allowing the continuous monitoring of the activity of a small laboratory termite- colony at 8 different feeding sites simultaneously. The test assembly consists of a small central polycarbonate-tube containing a colonie of Reticulitermes santonensis (de Feytaud) beeing connected with 8 external feeding sites by small glass-capillaries. The termites passing through the glass capillaries to and from the feeding sites are interrupting an infrared light-barrier. Each signal from the light-barriers is conditioned and fed to a PC-based signal-recognition-, monitoring- and storage-system. First results show that a colony of 500 individuals of Reticulitermes santonensis (de Feytaud) will need approx. 2 to 3 weeks for establishing a new, full functional hierarchy. A well established Reticulitermes- colony will show 80 to 100 passings per minute to and from the eight feeding sites. The activity of Reticulitermes santonensis (de Feytaud) shows no circadian activity rhythmic.
M Pallaske, E Graf, H Takiuchi


The use of preservative containing waste wood as substrate for growing greenhouse crops
1993 - IRG/WP 93-50011
In the Netherlands a large amount of waste wood and wood waste is produced every year. An important part of this amount comes from the pallet and packaging industries. One of the possibilities to re-use this relatively clean material is to convert it into substrates for growing crops in glass houses instead of the commonly used materials such as rock wool and glass wool. In this research, the influence of several material parameters such as wood species, texture, density, height, water holding capacity on the growth of cucumbers has been studied and this has been compared with the growth on rock wool, which is applied in approximately 95% of the glasshouses in the Netherlands. Furthermore, the influence has been investigated of anti blue stain preservatives on the growth of the cucumber plants, this kind of preservatives is often used in the dutch industry for protection of pallets. In general it can be concluded that when waste wood is to be used as substrate a few preservatives can be accepted and some others can not. The wood species teture, density, height and water holding capacity of the substrate showed to have only a slight effect on the growth of cucumbers.
W J Homan,H Militz


The effect of a chelator mediated fenton system on activation of TMP fibres and decolorization of synthesized dyes
2004 - IRG/WP 04-50223
The purpose of this work is to improve our current knowledge of the non-enzymatic mechanisms involved in the brown rot degradation of wood, but also to study the potential applications of a chelator-mediated Fenton system in activation of wood fibers and decolorization of synthesized dyes. In this work, Electron Spin Resonance (ESR) spin-trapping techniques were used to study the generation of hydroxyl radicals in a mediated Fenton system. The activation of Thermal Mechanical Pulp (TMP) fibers was also evaluated by ESR measurement of free phenoxy radical generation on solid fibers. The results indicate that low molecular weight chelators can improve Fenton reactions, thus in turn stimulating the free radical activation of TMP fibers. However, the data also show that excessive and prolonged free radical treatment may cause the destruction of fiber phenoxy radicals. A mediated Fenton system was evaluated for decolorization of several types of synthesized dyes as well. The results show that, compared to a neat Fenton process, the mediated Fenton process increased the production of .OH species to increase the decolorization efficiency. The color of a dilute liquid dyes (Carta Yellow RW, Carta Yellow G, or Cartasol Red 2GF) was effectively reduced to a colorless level after 90 minutes of treatment at room temperature by a mediated Fenton process. In conclusion, this study demonstrates the potential for application, but also the complexity of free radical chemistry in biological materials, especially with regard to the chelation of transition metals and the interaction between free radicals. The complexity of the dyes is similar to that of some organic wood preservatives and may provide a means for remediation of preservative contaminants in soils.
Yuhui Qian, B Goodell, J Jellison


Glass splinters as physical termite barriers: Optimized material properties in use with and without insecticidal pretreatment minimizes environmental contaminations
1991 - IRG/WP 1476
The major advantage of physically acting barriers against termites using sand or cinder is to be impenetrable for a number of termite species by showing environmental compatibility in a high degree. The major disadvantage of these barriers is the ability of termites to build galleries over them. Glass or glass-like materials are showing optimum material properties: crushed to a particle size from 0.5 to 1.5 mm very thin layers (10 to 20 mm thickness) reliably prevent termite penetration of Reticulitermes santonensis (de Feytaud) and Heterotermes indicola (Wasman) in laboratory studies as well as the penetration of Coptotermes formosanus (Shiraki) in Japanese field tests. On the other hand, the extremely high affinity of pyrethroids to this type of material makes it highly suitable for a stationary pyrethroid-carrier. Gallery-building by termites is completly suppressed after superficial treatment of glass splinters with pyrethroids. The high affinity of pyrethroids to glass surfaces causes high contact insecticidal properties by minimizing leaching and biodegradation-effects at the same time.
M Pallaske, A Igarashi


Micromorphology of Bamboo Fibers Degraded by Brown-Rot Fungus Gloeophyllum trabeum
2006 - IRG/WP 06-10576
The decay pattern of bamboo by brown-rot fungus was examined. In addition, the influence of polylaminate structures in bamboo fibers on the restriction of fungal decay was also investigated. The weight loss of bamboo Phyllostachys puberscens by the brown-rot fungus Gloeophyllum trabeum after 16 week incubation was about 25%. Parenchyma cells were severely degraded. Microscopical studies showed that G. trabeum removed the inner part of multi layers while the last layer in the polylaminate secondary walls, corresponding to S3 layer in the tracheids, remained essentially intact. Bamboo fiber walls were degraded at a considerable distance from fungal hyphae. Main decomposition of bamboo fiber cell wall by G. trabeum was similar to other brown-rot fungi in terms of preferential removal of inner part of secondary walls, remaining the last layer in polylaminate layer intact. Cytochemical work showed the production of hydrogen peroxide by the brown-rot fungus G. trabeum and the diffusion into the bamboo fiber walls. The effect of polylaminate structures and lignin levels at the narrow layers on restriction on fungal decay to bamboo fibers was also discussed.
Kwang Ho Lee, Chang Hyun Cho, Yoon Soo Kim


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


Effect of fiber type and content on the natural durability of wood flour/high density polyethylene composites against rainbow fungus (Coriolus versicolor)
2007 - IRG/WP 07-40387
In order to evaluate the effect of fiber type and content on the natural durability of wood flour/high density polyethylene (HDPE) composites against Coriolus versicolor, samples containing 25% and 50% by weight of various natural fibers and HDPE were selected. Natural fibers included in the study were wood flour, rice hulls, hemp fibers and newsprint. Samples containing 25% and 50% natural fiber had 1% and 2% compatibilizer (Maleic anhydride polyethylene (MAPE), respectively. Physical and mechanical properties of all specimens including water absorption, flexural modulus, flexural strength, impact strength and hardness were determined prior to and after incubation with the fungus for 14 weeks at 25 0C and 75% relative humidity. Weight losses of the specimens were also determined after incubation. Results indicated that samples containing 50% natural fiber were more susceptible to fungal decay as compared with those with 25% fiber. Rice hulls proved to be the most vulnerable natural fibers as nearly all mechanical properties of rice hulls composites significantly declined after contamination by the fungus.
A Karimi, M Tajvidi, S Pourabbasi


Performance of sintered glass screening as a potential physical barrier against subterranean termites in the laboratory and after 4 years of field test
2008 - IRG/WP 08-10646
This paper describes the performance of sintered glass screenings as a potential physical barrier against the subterranean termites, Coptotermes acinaciformis and Mastotermes darwiniensis in the laboratory and after four years of field testing in active above-ground mound colonies of Coptotermes lacteus. The laboratory results suggest that sintered glass is a viable control option against Coptotermes species in Australia, particularly against the subterranean termites C. acinaciformis and C. lacteus. There was a marked difference between the C. acinaciformis and M. darwiniensis termites’ ability to tunnel the sintered glass physical barriers in the laboratory bioassays. After 8 weeks of laboratory bioassay, the result suggested that C. acinaciformis was not able to tunnel through the sintered glass physical barrier, while M. darwiniensis tunnelled through the barrier within less than 48 hours. These laboratory and field results indicated that the sintered glass physical barrier can protect structural timbers from attack and damage by subterranean termites.
J R J French, B M Ahmed (Shiday)


Preparation and characterization of activated carbon fibers prepared from liquefied wood
2013 - IRG/WP 13-40636
Activated carbon fibers were prepared from liquefied wood through stream activation. The effects of activation temperature and time on the microstructure and surface functional groups of the liquefied wood activated carbon fibers (LWACFs) were studied using analysis of burning behavior, X-ray diffraction, nitrogen adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and SEM. The results showed that the burn-off value of the LWACFs increased gradually with the increase in temperature or time. All the LWACFs were far from being structurally graphitized, and in general, as temperature or time increased, the degree of graphitization and thickness of crystal structure increased. In addition, the LWACFs possessed rich micropores, and their specific surface area, pore volume, micropore size, and mesopore quantity were directly related to the activation temperature or time. The maximum specific surface area was found to be2641 m2/g. The fractal dimension values of all samples were close to 3, indicating that their surfaces were very rough. Furthermore, with an increase in temperature or time, the elemental content of carbon increased, while that or oxygen decreased. Meanwhile, as the temperature or time increased, the relative content of graphitic carbon decreased, whereas that of carbon bonded to oxygen-containing functions increased. The surface of samples prepared at higher temperature or with longer time formed a considerable amount of holes.
Wenjing Liu, Guangjie Zhao


Hybrid green composites manufactured with glass fiber and jute fabric skin by VARTM process: Fungal, mold, and termite resistance tests
2017 - IRG/WP 17-40780
Hybrid green composites are increasingly used in building applications due to the development of new production approaches. Biological performance of such composites is needed when they are employed in extreme conditions. Hybrid composite panels were manufactured by wood furnish, glass fiber, and jute fabric skin by the vacuum assisted resin transfer molding (VARTM). Petri dish test method was followed to evaluate fungal resistance of produced composite specimens by employing Fomitopsis palustris, Trametes versicolor and Serpula lacyrmans. The specimens were also subjected to mold resistance tests. Test specimens were then bio-assayed against the termites in laboratory conditions. The specimens were highly resistant to fungi tested and termites; however, mold fungal growth was observed on the surfaces of the specimens with glass fiber at 10, 15, and 20% loading levels (without jute fabric) and the specimens with 5, 10, and 15% glass fiber and with jute fabric. Results suggest that the hybrid composite panels can be used as an alternative product to conventional commercial composites in severe degradation conditions.
S N Kartal, E Terzi, M Muin, A H Hassanin, T Hamuoda, A Kilic, Z Candan


Understanding of the effect of ancestral and natural saltwater treatment on durability, fibers densification and chemical modification of palm wood
2018 - IRG/WP 18-10921
The palm-tree sector plays a very important role on both the socioeconomic and ecological levels, in Tunisia. There are three million trees in Tunisian palm plantations, ensuring a potential significant wood production, mainly in the craft and furniture industries. In the past, Date Palm wood (Phoenix dactylifera L.,) was also used as structural material. Its low natural durability and its low mechanical properties were improved by an ancestral preservative method consisting in the immersion of the trunk of the palm tree trunk freshly slaughtered for a period ranging from 1 to 2 years (depending on the species) in the salt waters of the Lake of Chot Djerid. This ancestral practice was disappeared, and it is always difficult to find more information on the different parameters involved in this kind of process. The objective of this work was to assess the main technological qualities of palm wood preserved by salting while trying to retrace the steps of this natural and eco-friendly preservation process. Two Common date palm cultivars woods (Kentichi and Deglet Noor) with ages ranging from 40- to 50-years, native and preserved by salting in the Chot Djérid were used for the experiments. Each wood samples were collected at the Regional Center of Research on Oasis Agriculture - Degache - Southern Tunisia. Densities (air-dried, water saturated, basic), mechanical properties, decay and termites resistances tests were performed on native and salt water - treated palm woods. The first results showed a significant increase of the air-dried density of palm wood samples which increases after their wood salt water immersion. Salt water treatment allows improving greatly the palm wood MOR in bending and paralleling to the fibers. Termite’s resistance tests highlighted that native and treated palm wood had a similar degradation level after termite exposure, but the termite mortality rate was higher for the treated wood than that of native palm wood. Extractives, lignin and cellulose contents are slightly more abundant in the control samples except for the hemicelluloses which are more abundant in the treated palm wood sample. Additional analyses conducted with an ICP-AES 700 Agilent device, evaluating the mineral compositions between native and salt-treated palm woods, give us some explanation ways about the performance improvement of wood after such a natural preservation process.
M T Elaieb, A Namsi, M Tella, M-F Thévenon, K Chandelier


Limiting Polysaccharide Motion Protects Wood From Decay
2020 - IRG/WP 20-40890
It is well known that chemical modifications to improve decay resistance also reduce the equilibrium moisture content (EMC) of wood. The mechanism of this action, however, has been the subject of much debate. Several groups have suggested that decay resistance is a result of lower diffusion rates of fungal degradation agents through the wood cell wall. A recent paper explained the fundamental principles governing diffusion through the wood cell wall. This current paper summarizes the findings in that paper with respect to decay resistance of modified wood. In short, large scale motions of the amorphous polysaccharides of the wood cell wall are necessary for diffusion of degradation agents during incipient decay. Many wood modifications are likely preventing decay by preventing these motions. Water promotes large scale motions of cell wall polysaccharides by increasing free volume, increasing the distance between polymer chains, and reducing the number of hydrogen bonds between polymer chains.
C G Hunt, S L Zelinka, J E Jakes


Silicate coatings for wood substrates
2020 - IRG/WP 20-40906
Silicate coatings are surface finishing products containing alkali metal silicates or ethyl silicates as main binders. They are traditionally designed and well established for mineral substrates or corrosion protection of steel. The interest for these coatings in wood field is growing because of the benefits they could provide such as high durability, weathering resistance and fireproofing and sustainability. Contrary to conventional substrates (concrete, stones, steel), wood is organic, a highly dimensionally instable material. So, a durable coating for wood must meet a compromise between adhesion, liquid water and water vapour permeability and its flexibility. This is essential to accommodate surface strains developed, when wood swells and shrinks, to avoid cracking and debonding. Appropriate formulation combining painstakingly inorganic and organic components with eventually surface pre-treatments could overcome the adhesion and flexibility drawbacks related to wood finishing and weathering. Few silicate-based products for wood are already in the markets, but scientific literature in the field remains not significant and inaccurate. This poster paper presents an ongoing research project financially supported by The Slovenian National Research Agency (ARSS) under the frame of EU Marie Curie “Seal of excellence” and the University of Ljubljana. The project will provide outstanding basic-knowledge correlating formulations-coating properties–weathering and potential improvements for development of new products and application processes.
A M Cheumani Yona, M Pavlič, M Petrič


Application of suberin fatty acids extracted from birch bark for wood coating
2021 - IRG/WP 21-40914
It is well known that chemical modifications to improve decay resistance also reduce the equilibrium moisture content (EMC) of wood. The mechanism of this action, however, has been the subject of much debate. Several groups have suggested that decay resistance is a result of lower diffusion rates of fungal degradation agents through the wood cell wall. A recent paper explained the fundamental principles governing diffusion through the wood cell wall. This current paper summarizes the findings in that paper with respect to decay resistance of modified wood. In short, large scale motions of the amorphous polysaccharides of the wood cell wall are necessary for diffusion of degradation agents during incipient decay. Many wood modifications are likely preventing decay by preventing these motions. Water promotes large scale motions of cell wall polysaccharides by increasing free volume, increasing the distance between polymer chains, and reducing the number of hydrogen bonds between polymer chains.
A Kumar, Risto Korpinen, Veikko Möttönen