Viscoelastic thermal compressed (VTC) wood has due to the high wood density and thus improved mechanical properties great potential in the development of high-quality wood products. Its wider utilization is limited by set recovery of compressive deformation, which occurs when VTC wood is exposed to environment of increased humidity. Thermal modification is one of the process which can improve the dimensional stability of wood and resistance to fungal decay. In this thesis the problem of set recovery of compressive deformation was studied. Samples of spruce and beech wood, which were previously densified by the VTC process, were thermally modified with a thermal modification process at different temperatures (190 °C, 200 °C, 210 °C, and 220 °C). Set recovery of compressive deformation was examined after 5 water soaking cycles. It was found that set recovery of compressive deformation depended on the temperature of thermal modification and wood species. It was determined that stability of compression deformations of the VTC wood depends on the level of thermal modification. Thermal modification at temperature 220 °C caused significant mass loss, better stability, and reduced set recovery of compressive deformation, and thus improved the properties of VTC wood.
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