A natural flavonoid treatment of wood: artificial weathering and decay resistance
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ORIGINAL
A natural flavonoid treatment of wood: artificial weathering and decay resistance Eylem D. Tomak1 · Mahmut A. Ermeydan1 Received: 14 January 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this study, a natural flavonoid, chrysin, was used as a wood impregnation agent and evaluated in terms of artificial weathering and decay resistance of wood. For this purpose, Scots pine samples were impregnated with chrysin after tosylation pre-treatment and, then, exposed to artificial weathering for 672 h. Color, surface roughness, contact angle and macroscopic changes were recorded during the test period. Furthermore, surface chemical components and morphological changes were evaluated with ATR-FTIR and SEM, respectively. Decay resistance of samples was assessed using a brown-rot fungus (Coniophora puteana) and a white-rot fungus (Coriolus versicolor) for both leached and un-leached samples. In the results, chrysin impregnation was found efficacious in preventing C. puteana attack. However, a proper protection was not ensured against C. versicolor attack. Tosylation was effective in resisting decay by both fungi, but it was not effective in decreasing weathering degradation on the wood surface as chrysin impregnation did. Chrysin decreased color changes and surface roughness. In addition, surface hydrophobicity increased, and lignin degradation decreased with chrysin impregnation. Cracks on treated samples seemed to be an important disadvantage after exposure to weathering agents. Results of chrysin impregnation gave some promising results to improve service life of non/low-durable wood species in outdoor use.
1 Introduction Wood is a durable renewable material when properly used and maintained in service. However, it is rapidly decomposed by biotic or abiotic agents alone or in a combination of some environmental conditions. Fungi and insects can degrade or destroy wood components. Wood is also dimensionally unstable at moisture content below fiber saturation point, and swells and shrinks as it wets and dries, respectively. Besides, exposure to atmospheric agents and sunlight may cause physico-chemical damage on the wood surface, known as weathering. Wood surface gradually develops a grey color and roughened texture under weathering conditions. Wetting and drying cycles of the weathered wood surface lead to surface checking, warping and cracking, and Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00107-020-01578-x) contains supplementary material, which is available to authorized users. * Eylem D. Tomak [email protected]; [email protected] 1
Department of Forest Industrial Engineering, Faculty of Forestry, Bursa Technical University, 16310 Bursa, Turkey
mechanical failures. The major changes by weathering are photo-chemical damage of wood components especially lignin and extractives, oxidation of breakdown products, leaching of soluble products and mechanical damage of surface components (Zabel and Morell 1992). Th
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