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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


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


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 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


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


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)


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


Surface Protection of Wood with Metal Acetylacetonates
2017 - IRG/WP 17-40802
Metal acetylacetonates are coordination complexes of metal ions and the acetylacetonate anion. They have diverse uses as catalysts, cross-linking and curing agents and adhesion promotors. Some metal acetylacetonates can photostabilise polymers whereas others are photocatalysts. We hypothesise that the ability of metal acetylacetonates to photostabilise wood will vary depending on the metal in the coordination complex. We treated yellow cedar veneers with different acetylacetonates (Co, Cr, Fe, Mn, Ni, and Ti) and exposed the veneers to natural weathering in Australia for 20 days. The weight losses, erosion, tensile strength, colour, surface microstructure and chemistry of the treated veneers after weathering were compared with those of the controls (untreated and treated with DMF). Nickel, manganese, titanium and iron acetylacetonates were more effective than cobalt acetylacetonate at photostabilising wood, based on the different measures we used to assess the degradation of weathered veneers. Iron and nickel acetylacetonate were more effective at photostabilising lignin in weathered veneers than the other metal acetylacetonates possibly because they were able to complex lignin. Further research is needed to test this hypothesis. Our findings support our hypothesis and accord with a previous study that showed that titanium acetylacetonate could photostabilise radiata pine veneers.
Yuner Zhu, P D Evans


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