【作者】 谢满华；

【导师】 赵广杰；

【作者基本信息】 北京林业大学 ， 木材科学与技术， 2006， 博士

【摘要】 为了在分子水平上弄清楚木材主成分之间的相互作用关系,以及获得不同塑化处理后,木材在应变条件下内部分子结合形式的变化信息,不仅能为木材的非晶化、化学改性、弯曲部件成型等奠定理论基础,还能为木材加工、综合利用等开辟新的途径和方法提供技术参数,同时还能丰富木材流变学理论。本研究首次应用化学动力学方法分析了脱木素和脱半纤维素木材的应力松弛,并验证了其有效性,使木材主成分之间的相互作用关系在分子水平上有了一个更好的理解;同时为了考察温度变化对木材主成分变形的影响,测定并分析了温度周期变化过程中未处理木材及处理木材的应力松弛特性。以DMSO膨胀处理及DEA-SO2-DMSO非晶化塑化处理为例,测定了两种处理木材在水浸渍过程中的X射线衍射及Tobolsky间歇应力松弛,分析了水对处理木材结晶度及内部凝聚力的影响;通过未处理和两种处理木材在不同温度水中的连续应力松弛测定,应用Eyring的绝对速度反应理论计算并获得了松弛过程中的各热力学量,分析了在水中松弛过程中不同阶段木材内部发生的化学反应;并首次采用SMCIR连续·不连续双曲线应力松弛法定量了轴向拉伸应力松弛过程中木材内部产生的架桥量,明确了交联反应的类型;为了了解干燥对处理木材塑性变形固定的影响,测定了未处理和两种处理绝干木材在温度下降过程和上升过程中的应力松弛,分析了温度变化对处理绝干木材应力松弛的影响;根据多个温度水平下的连续应力松弛测定曲线,计算松弛过程的热力学量,考察了绝干木材在松弛过程中内部发生的分子变化机理,同时也用间歇法定量了木材内部新形成的架桥量,并在此基础上构筑处理木材在松弛过程中内部分子构造的变化模型。本论文的主要结论归纳如下:(1)木材应力松弛的化学动力学分析表明,未处理木材的活化体积和活化自由能都随着含水率的增加而减少,脱木素处理和脱半纤维素处理木材却没有表现出这种变化规律,但处理木材的活化能总是比未处理木材的小。化学处理对木材的结构产生了不同程度的影响,使水分子对木材主成分的作用方式发生了变化。根据应力与时间的双对数关系得到的松弛速率分析,验证了化学动力学方法应用于描述化学处理木材应力松弛特性的有效性性。(2)通过木材在温度周期变化过程中的应力松弛研究,发现,未处理木材和化学处理木材在25℃松弛4小时后,应力几乎水平下来,升温后,应力立即急剧下降,温度下降时,应力又急剧回复。应力的急剧变化主要是在温度的变化过程中产生,当温度达到平衡态后应力的变化很小。温度变化对木材里的应力变化产生了很大影响,但是不管外界环境怎样无常变化,长期外力作用下的木材在相同的平衡温度及含水率条件下的形变随时间逐渐增大的变化规律没有变化。更多还原

【Abstract】 To clarify the interaction between wood primary components based on a molecular level, and to obtain the change information of bonding form between molecules in different soften or decrystallized wood, can not only provide theoretical basis for decrystallization, chemical improvement of wood and wood bending, but also can offer technical parameters for new approach and ways of wood processing and integrated utilize, at the same time can also enrich the wood rheology theory. This research analyzed the stress relaxation of delignified wood and hemicellulose-removed wood based on the chemical dynamics theory, and verified its validity on stress relaxation, which made we have a more fundamental understanding of the interaction between wood components on a molecular level; In order to review the effect of temperature change on the deformation of wood molecules, determined and analyzed the relaxation behavior of untreated and chemically treated wood during periodical temperature changing. Take DMSO swollen treatment and DEA-SO2-DMSO decrystallization treatment for example, the X-ray diffraction and the Tobolsky’s intermittent stress relaxation of treated woods were determined during soaking in water, analyzed the effects of water on crystal degree and inter-cohesion of treated woods. According to these continuous relaxation curves measured in water with different temperatures, various thermodynamic quantities were obtained by using Eyring absolute rate theory, and reviewed the chemical reactions in wood which occur in different relaxation process. For the first time quantify these crosslinkings formed in the process of tensional relaxation by using the SMCIR intermittent stress relaxation way, and defined the cross-linking reaction types. In order to find out the contribute of drying to the fixation of deformation of chemically treated wood, stress relaxation of oven-dry untreated and treated wood was measured during the process of temperature elevation and descend, then analyzed the effect of temperature change on relaxation mechanism of treated oven-dry wood. According to continuous relaxation curves of oven-dry treated wood under various constant temperature, calculated the thermodynamics of relaxation process and discussed the mechanism of molecule change in wood, at the same time, also quantified these cross-linkings produced in wood by intermittent method and on the basis of which the model of molecular change during relaxation process of chemically treated was constructed. The research results obtained are as follows,(1)The chemical dynamics analysis on stress relaxation of wood indicated that, the active volume and active energy of untreated wood decrease with the increase of moisture content, and as it isn’t for delignified wood and hemicellulose-removed wood, but at random moisture content the active energy of treated wood is smaller than that of untreated.更多还原