The Study On The High Temperature Heat Treatment Of Chinese Fir

With the reduction of natural forest, the tendency of development and utilization of wood has turned to quick-growing plantation. The key subject must be solved is how to use quick-growing plantation efficiently. High temperature heat treatment is new modification method of wood in recent years. The wood of quick-growing plantation have better durability,weatherability and dimension stability after heat treated modification. It's safe and environmental. The heat treated wood is widely used in terrible conditions like exterior decoration n exterior building,park facilities,Sauna room and so on.In this paper, the Chinese fir was used as sample to the study. The heat treatment was taken place under 4 processing temperature conditions(160℃,180℃,200℃and 220℃) and 4 processing time condition(lh,2h,3h and 4h). The color, chemical change of internal composition, cellulosecrystallity and dimensional stability of the treated wood were examined. The results are shown as follows:1.With the rising of processing temperature and extending of processing time, the color of treated wood was turned from yellowish-white to brilliant yellow, then to tawny, at last, it became to dark. The lightness index L and color index b would reduce with the processing temperature rising; and with the processing time extending, the lightness index L would reduce, the color index b would rise firstly and then turn to reducing.2. The FTIR analysis shows that with the processing temperature rising and keeping time extending, the hydroxyl groups carbonyl groups in wood reduce. Comparatively speaking, hydroxyl groups reduced much more. Because of that, the water absorption power of wood is weaken, so the dimensional stability of wood is increased.3. The influence of high temperature heat treatment on the location of diffraction peak of 002 crystal plane in crystalline region within the cellulose is not significant. In the different 4 processing temperature levels, the effect of processing time on the cellulosecrystallity presents different ways; in the condition of same processing time, the cellulosecrystallity tends to rising—declining—rising with the processing temperature increasing. 4. The water absorption, hygroscopicity and thickness swelling of wood would reduce after heat treatment. Compare to check sample, the equilibrium moisture content and moisture content of the heat treated wood are much lower. With the processing temperature rising and processing time extending, the differences is biger and biger. So it is shown that high temperature treatment is able to increase the dimensional stability of wood.