Effects Of Heat Treatment Temperature On Chemical Compositions And Structure Of Pterocarpusmacarocarpus Kurz Wood

Wood heat treatment technology is popular because of its green and effectivity in improving the properties of wood. For further broaden the research scope of heat treated wood, and introduced a new analysis method of heat treated wood, in this paper, Pterocarpusmacarocarpus Kurz (P. Kurz) wood was heat treated at temperatures of 150℃,190℃ and 230℃ for 2 h in airtight equipment with an atmosphere within comprising less than 2 percent of oxygen content. By means of chemical composition analysis, FT-IR, two-dimensional correlation infrared spectroscopy (2D-IR), NMR and Gc/Ms technology, this paper analysed the heat treatment temperature effects on P. Kurz wood chemical composition, and provide theoretical basis for study the effects of heat treatment on the main chemical compositions of wood, and broaden the research scope of heat treated wood.The results are as follows:(1) In the process of heat treatment, the thermal stability of hemicellulose is the worst. At 150-190℃, the hemicellulose degradation was the most obvious, decreased by 8.88%. The cellulose content decrease was started obvious after 190℃, reduced by 4%. The lignin content increased after 190℃ significantly, increased by 5.37%, and from 150 to 190℃, the change of extractive content is relatively obvious, rose 0.42%.(2) In the FT-IR analysis, the absorption peaks intensity of hemicelluloses at 1739,1248 and 781 cm-1 decreased, incidating the hemicellulose degraded with the increasing temperature hemicellulo The changes of absorption peaks intensity at 1639 and 1111 cm-1 in cellulose incidated the adso water of cellulose reduced and the crystallinity increased. The changes at 1592 and 1317 cm-1 incidated the lignin degradation.The changes at 1267,1219 and 1121 cm-1 incidated the changes of lignin structure units.(3) 2D-IR spectra showed that the thermal perturbation sensitivity of holocellulose water absorption peak at 1649 cm-1 was always strongest in different temperatures. The absorption peaks at 1000～1300 cm-1 was the strongest in 150 ℃, suggested the hemicellulose degradation. The automatic peaks vibration intensity of cellulose were weaker than hemicellulose. The absorption peaks at 1000-1300 cm-1 in cellulose was the strongest in 190 ℃, incidating maybe the C-O-C of cellulose degradated. The automatic peaks vibration intensity of lignin were weakest at 190 ℃, but their relatively thermal perturbation sensitive were strongest, which may incidate the changes of lignin structure units.(4) Through FT-IR,1H NMR and Gc/Ms analysis of P. Kurz wood extractives, it was showed that, the flavonoids substances and phenolic compounds in P. Kurz wood extractives decreased gradually with increasing temperature, and the content of ketones and aldehydes compounds increased, suggesting the degradation of P. Kurz wood extractives with the increasing temperature. The 2D-IR analysis showed that, the automatic peaks vibration intensity and thermal perturbation sensitivity of flavonoids and phenolic compounds were strongest at 190℃, and decreased significantly at 230℃.