非均匀结构花旗松热处理材的制备及性能评价

以花旗松为试材,采用平板加热工艺在温度为180、220℃条件下进行热处理,使试材表层温度达到160℃而芯层温度控制在150℃内,制备一种具有非均匀结构的新型热改性材,并探讨热处理材表芯层吸湿性能及化学组分差异。结果表明:平板加热法可以在木材断面形成层次分明的非均匀结构,试材含水率水平是影响表芯层差异的主要因子,初含水率3.8%木材表芯层温差显著小于初含水率为15.0%试材;动态水蒸气吸附试验表明,处理材表层吸湿性低于芯层,且在高湿条件下两者差异更加显著,试材表面形成了一层低吸湿性外壳;红外光谱分析及X射线光电子能谱分析表明,热处理后表层半纤维素发生降解,木质素质量分数增加,是试材表层吸湿性降低及断面层次结构形成的内在原因。

Preparation and Properties Evaluation of Heat-treated Douglas Fir with Uneven Structure

Douglas fir(Pseudotsuga menziesii)were thermally treated by heating platens at 180℃or 220℃to prepare a new type of heat-treated wood with uneven structure,so that the temperature of the wood surface reached 160℃and the temperature of the core layer was controlled within 150℃,and the hygroscopicity and chemical composition of the surface-core layer of the heat-treated wood were discussed.An uneven structure on the cross section of the samples was formed after platen heating.The moisture content of wood was the main factor affecting the treatment effects.The temperature difference between surface and core of heat-treated wood with initial moisture content of 3.8%was less than that of heat-treated wood with moisture content of 15.0%.Dynamic water vapor sorption tests showed that the moisture sorption of the surface layer was lower than that of the core layer.The difference between the two layers was more significant in high humidity conditions,indicating that a hydrophobic shell was formed on the surface of the wood.By FTIR and XPS,the degradation of surface hemicelluloses and the increase of lignin content after heat treatment were the main contributors to the decrease of surface hygroscopicity and the formation of uneven cross-section structure.