Stress Relaxation Of Chemically Treated Wood

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.