Natural durability of wood species is variable. Chemical wood preservatives, such as biocides are necessary for extension of their service life. Many methods have been developed to increase the resistance of wood and wood products against wood-destroying organisms during the last years. The most frequently used methods are chemical and thermal modification of wood. In wood modification the basic chemistry of the cell wall polymers is altered, which can change important properties of wood, such as durability, dimensional stability, hardness and UV-stability. Controlling of the moisture content in wood is a very effective way to protect wood against wood-destroying fungi. Polyacrylates have been known from the field of conservation of damaged wood. They are able to decrease the equilibrium moisture content of treated wood and to increase mechanical properties, such as hardness, compression strength and static bending strength. However, the dimensional stability is improved slightly. Our experiments have demonstrated that polyacrylates are not able to increase the resistance of beech and spruce wood against the brown-rot fungi Coniophora puteana and Gloeophyllum trabeum. For wood modification we used toluene solution of the polyacrylate Paraloid B-72 (copolymer of methylacrylate and ethylmethacrylate) in the concentrations of 2 % and 10 %. The mass losses of modified wood samples after the mycological test (according to the standard EN 113 during 16 weeks) were similar as of the untreated ones. The fungi were able to penetrate the polyacrylate film on the inner surface of wood cell walls and to decay the wood. The average mass losses of modified samples after rot by Coniophora puteana were 26.9 % (at using of 2 % Paraloid B-72) or 21.7 % (at using of 10 % Paraloid B-72) for beech wood and 27.0 % or 29.7 % for spruce wood. The average mass losses of modified samples after rot by Gloeophyllum trabeum were 37.7 % or 36.1 % for beech wood and 27.1 % or 26.5 % for spruce wood. The better results have been achieved if polyacrylate was combined with TCMTB fungicide (2-tiocyanomethyltiobenztiazol). TCMTB fungicide was applied into wood either before the polyacrylate (double impregnation) or together with polyacrylate (impregnation with mixture). For double impregnation technique, the mass losses of modified beech and spruce woods were close to zero. On the other hand, in the case of mixture impregnation we noticed relatively worse effect of the TCMTB fungicide against fungi. In this situation a durability of the modified wood was lower, probably due to blocking of the fungicide molecules with the larger polyacrylate macromolecules.

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