摘要
木材热处理可以显著降低木材的吸湿性,是提高其尺寸稳定性的有效改性方法。以南方松热处理材和对照材为试材进行动态水蒸气吸附试验,并借助拉曼光谱对两种试材的化学组分进行比较,探索热处理对木材吸湿性能的改性机理。结果表明:在本试验条件下,热处理不仅降低了木材的吸湿量,也改变了其吸湿特性,表现为热处理材平衡含水率变化率的降低和吸湿滞后性的增强。在实际应用中,这表明热处理材即使在环境湿度变化较大的情况下也能保持较好的尺寸稳定性。拉曼光谱分析表明,木素的结构变化是热处理材形成其吸湿特性的主要内在原因之一。热处理后木素在细胞壁中的相对含量有所上升,结构发生了重组,使木材细胞壁结构变得更加稳固而缺乏弹性,对木材的吸湿和平衡起到了阻滞作用。
As an effective modification method, heat treatment improves the dimensional stability of wood by lowering its hygroscopicity. The degradation of hemicelluloses and the increase of cellulose crystallinity are believed to be the main reasons for the property changes, while the contribution of lignin is still not fully understood. Some suggested that the condensation of lignin oceured during the heat treatment process, the cross-linking structure thus was formed and made the wood being hydrophobic. Others questioned it and suggested other lignin reaction types. In this study, dynamic water vapor sorption experiments were carried out on heat-treated and untreated southern pine wood. The chemical compositions of both samples were analyzed using Raman spectroscopy to investigate the mechanism after the property modification. The results showed that the heat treatment not only lowered the sorption amount of the treated wood but also altered the pattern of its sorption process, which was demonstrated by the decrease of the change of moisture content as a function of relative humidity and the increase in sorption hysteresis of the heat-treated wood. All these indicated the dimensional sta- bility improvement of heat-treated wood even in a condition with greatly varied humidity. Raman spectroscopy analysis in- dicated that lignin was one of the key factors affecting the sorption behavior of the heat-treated wood. Heat treatment in- creased the content of lignin in the cell walls and changed its structure. As a result, a more rigid cell wall was formed, which hindered wood from moisture sorption and made the hysteresis more significant.
出处
《林业工程学报》
北大核心
2016年第5期15-19,共5页
Journal of Forestry Engineering
基金
国家林业公益性行业科研专项(201404504)
江苏高校品牌专业建设工程资助项目(TAPP)
关键词
木材热处理
动态水蒸气吸附
拉曼光谱分析
平衡含水率
吸湿滞后
wood heat treatment
dynamic water vapor sorption
Raman spectroscopic analysis
equilibrium moisture content
sorption hysteresis
