植物油涂饰处理对热改性落叶松耐候特性的影响

参考芬兰Thermo-Wood~?工艺规程,对落叶松板材分别在160、180和200℃常压过热蒸汽环境下进行高温热改性处理;随后对经过热改性后的板材及常规室干对照板材分别进行了天然植物油涂饰处理,分别使用商品化木蜡油(底油和面油)、自制木油(预聚合大豆油)。在人工模拟高湿环境下测试各类植物油涂饰后的木材相对吸湿率、平衡含水率及橫纹相对变形率等各项技术指标。结果表明,热改性木材经植物油表面涂饰处理后,天然植物油蜡成分有效地浸入木材细胞壁组织,木材表层组织对环境湿度变化的敏感性降低。三种涂饰处理方法中,涂饰商品化木蜡油底油、木蜡油面油的方案最为有效,其木材横纹相对变形率均较未涂饰木材显著降低;随着热改性温度的升高,各类涂饰试件的平衡含水率、相对吸湿率呈现总体下降趋势,加热温度对各类试件的平衡含水率、相对吸湿率存在显著影响。

Impact of Natural Oil Painting on the Weathering Characteristics of Thermally Treated Larch Lumber

Based on the finnish thermo-wood technical procedures, larch lumbers were thermally treated by the atmospheric super-heated steam, with the target temperatures controlled at 160℃, 180 ℃, and 200 ℃, respectively. These thermally modified larch lumbers plus the control untreated ones were then surface painted by the natural plant oil, which included the commercial wood wax oil (priming, sealer) and self-prepared wood oils (prepolymerized soybean oil). Consequently, these thermally treated plus natural oil painted lumbers were further put inside an environmental conditioning chamber, where the temperature was set as constant and the relative humidity was manipulated at a stepwise increase mode, namely, from 30% to 50%, finally reaching 70%. At the end of each equilibrium stage, the weathering resistance variables, including tangential relative deformation rate, equilibrium moisture content and relative adsorption rate, were determined accordingly. As thermally treated lumbers were surface painted by the natural plant oils, these oils and waxes would penetrate further inside the wood cell wall tissues. In consequence of this, the susceptibility of wood surface tissues to the moisture fluctuations would be decreased. Among these oil painting procedures utilized herein, the one with both priming and sealer oils was the preferable option, under which the relative deformation rates decreased significantly in comparison with the control unpainted samples. Under the current test settings, as the thermal treatment temperature increased, the equilibrium moisture content and relative adsorption rate of all groups of samples decreased accordingly. According to statistical analysis, the thermal treatment temperature showed a significant influence over the equilibrium moisture content and relative adsorption rate of these natural oil coated larch lumbers.