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The decay resistance of chemically modified aspen composites to the white rot fungus Coriolus versicolor (L.) Quelet
1998 - IRG/WP 98-40122
Chemical modification of Aspen wood (Populus tremula L.) in the form of solid wood, veneers and sawdust was undertaken by a two step procedure consisting of esterification with maleic anhydride (MA) and subsequent oligoesterification with MA and glycidyl methacrylate (GMA) or allyl glycidyl ether (AGE). Modified wood was thermoplastic and was thermally formed by hot-pressing to produce veneer or solid wood samples with smooth glossy surfaces, while plastic-like wafers were obtained by hotpressing modified sawdust. Chemical modification alone was shown to enhance the biological resistance of Aspen to decay by Coriolus versicolor. In addition, hot-pressing enhanced decay resistance of both unmodified wood and esterified wood veneer samples, although no improvement was found by hot pressing oligoesterified wood. The most effective treatment for the improvement of decay resistance was chemical modification of the sawdust in conjunction with hot-pressing. A microscopic examination of chemically modified and control samples following exposure to the fungus showed more extensive colonisation and decay in untreated, unpressed samples.
M C Timar, A J Pitman, M D Mihai

Gaseous treatment of timber with allyl isothiocyanate. Fungicidal and insecticidal effects
1996 - IRG/WP 96-30108
Gaseous treatment with allyl isothiocyanate (AIT) was tested for its effects on the growth of microorganisms on the wood substrate and the mortality of subterranean termites and powder-post beetles. Toxic limits of AIT were determined as concentrations in the air when an AIT-treated filter paper was placed in a sealed container with fungus-inoculated wood specimens. Those were <3.8 ppm for Aureobasidium pullulans, 7.5-15 ppm for Aspergillus niger, 30-59 ppm for Gliocladium virens, 59-118 ppm for Penicillium funiculosum and >118 ppm for Rhizopus stolonifer. LD 50 values were determined for insects. Twenty workers of Coptotermes formosanus or 10 adults of Lyctus brunneus were placed in an air-circulated glass bottle, and the mortality of the test insects was recorded after 24 hours. LD 50/24h were 10-13 ppm and approximately 80 ppm in the air for Coptotermes formosanus and Lyctus brunneus, respectively.
K Tsunoda, T Yoshimura

Development of beech wood thermo-chemical modification treatments based on different vinylic derivatives of glycerol and polyglycerol
2019 - IRG/WP 19-40855
In this study, a combination between chemical and thermal wood modification has been investigated. Seven types of a low concentration of 10% aqueous additive solution of vinylicglycerol [glycerol-maleic anhydride (Gly-MA), glycidyl methacrylate (GM), and Glycerol methacrylate-maleic anhydride (GM/MA(2eq))], vinylicpolyglycerol [polyglycerol-maleic anhydride (PG-MA), polyglycerol methacrylate (PGM), and polyglycerol methacrylate-maleic anhydride (PGM/MA(3eq))], and maleic anhydride (MA) were impregnated into European beech wood (Fagus sylvatica), known for its low dimensional stability and poor natural durability. Varied with different curing temperatures at 103, 150, 200, and 220oC under inert condition, the modified wood and control were then characterized for their physical, mechanical, decay, and termite resistance properties. We found that, at the same initial weight percent gain (WPG) value (8 – 11%), mass changes (∆m) after thermal treatment, bulking (B), weight loss due to leaching (WLL), swelling (S), wettability, modulus of elasticity (MOE), and modulus of rupture (MOR) values of the additive-treated wood decreased as the curing temperature increased. In contrast, anti-swelling efficiency (ASE), decay resistance against Coriolus versicolor, and termite resistance against Reticulitermes flavipes values of additive-treated wood increased considerably for some treatments as the curing temperature increased, with better results at 200 and 220oC. In other words, the study has disclosed that the addition of some selected additives combined with thermal treatment can improve wood decay resistance and termite resistance better than untreated wood or wood with only thermally modified treatment.
M Mubarok, S Dumarcay, H Militz, K Candelier, M-F Thevenon, P Gerardin