Study On Micromechanics And Heat-treatment Of Chinese-Fir And Masson-Pine

In this study, plantation of Chinese-Fir and Masson-Pine for the object, the Zero-span tensile strength of tracheids, in-tree variation and the effect of moisture content of the Chinese-Fir and Masson-Pine were researched, on the other hand on the plantation of Chinese-Fir and Masson-Pine for high-temperature heat-treated and tested the chemical components, crystallinity, elastic modulus of tensile in vertical direction of small sample. The focus of study is that treatment-temperature and treatment-time for the effects of specific modulus, aimed at revealing the mutative rule of mechanical property according the nature of heat treatment modified.The Zero-span tensile strength of tracheids of the Chinese-Fir and Masson-Pine were researched. It was shown that the optimum thickness of samples and clamping pressure for Z-span tension was 80μm and 70psi respectively. The longitudinal tensile strength of early wood tracheids of the Chinese-Fir is from 310 to 733 MPa with an average of 499 MPa and tensile strength of Masson-Pine is from 300 to 590 MPa with an average of 461 MPa. The longitudinal tensile strength of early wood tracheids has no significant variation was observed along tree height from1.3m to7.3m, and no significant variation trend. The effect of moisture content on the tensile strength of tracheids no significant variation but the strength at air dry state is higher than water saturation state.Heat treatments at temperatures form 160℃to 220℃for times from 1h to 3h. Analysis of variance results of chemical components in treated wood showed under the level of 0.05, the effect of heat treatment temperature on the Holocellulose content significantly variation. Processing temperature and processing time onα-cellulose and lignin no significantly variation. The content of Holocellulose of Chinese-Fir has shown a downward trend with increasing temperature and time. The content of Holocellulose of Chinese-Fir has debased about 13.8% compared to untreated wood and 13.1% lower Masson-Pine around. Thermal stability ofα-cellulose relatively good, when the temperature reaches 180℃the content decreased significantly. Theα-cellulose content of Chinese-fir debased about 23.5% compared with the untreated wood, Masson-Pine most about 21.5% lower. Lignin content has a clear upward trend with the increase in processing temperature and processing time. Lignin content of Chinese-Fir up to about 12% higher compared with the content of untreated wood, Masson-Pine up to about 8.9% higher. The content of Hemicelluloses has shown a downward trend with increasing temperature when the processing time is 1h. When the processing time is 3h, the performance for the upward trend. When processing time is 1h, the temperature is below 180℃, crystallinity shows an upward trend, the temperature higher than 180℃, the crystallinity lower. When the processing time is 3h, the temperature is 160℃higher than those made of untreated wood crystallinity and shows the upward trend. Crystallinity has a slight downward trend until 180℃, and then also with the crystallinity increase gradually in temperature.The longitudinal tensile specific modulus of treated Chinese-Fir is 15.28-38.75 (MPa·m³Â·kg^-1), and the mean value is 27.05(MPa·m³Â·kg^-1), the coefficient of variation is 16.11%. The longitudinal tensile specific modulus of treated Masson-pine is 13.72-33.30(MPa·m³Â·kg^-1), the mean value is 22.51(MPa·m³Â·kg^-1), the coefficient of variation is 24.4%. The longitudinal tensile specific modulus has significant variation between the five trees. Processing temperature and processing time on the longitudinal tensile specific modulus of Chinese-Fir and Masson-pine has no significantly variation. As the processing temperature and time increased, the chemical components and changes trend in specific modulus are consistent basically.