Study On Water During Compression Of Fast-Growing Wood Of China Fir

Through analyzing the fast-growing china fir's compression shaping condition , water, physical and mechanical properties during compression process, and observing the change of the micro structure ,we can draw the following results:(1) Utilize the fast-growing china fir produce compressed wood feasible. Its best process parameters are: compression ratio is 50~60%,thickness after compressed is 13mm,moisture content before compressed is 50%, hot compress time is about 30min, hot compress temperature is between 180℃ and 200℃.(2) Through lengthways , radial, tangential water distribution curve of compressed wood, water distributions are uneven and easy to warp and distort.The higher the moisture content of compressed wood is, the greater the compressed wood restore; the more crooked the water distribution curve is, the easier warping is out of shape. With moisture content before compressed being high, water distribution curve change very heavy, especially the big size compressed wood. In order to reduce moisture content, make the water distributed steadily, we can adopt two methods: first, make the wood before compressed as possible as low; second, hot compress time tries it's best to be long.(3) Moisture content before compressed has influence on compressed wood's physical and mechanical properties. When moisture content before compressed is about 50%, compressed wood's hardness , bending elastic modulus , bending strength is best, toughness show a tendency to drop with moisture content increase, wearability is the best when wood compressed under the full water stated. WL decreases with moisture content rising definitely before compressed. Compressed wood's physical and mechanical properties of have obvious improvement to natural material.(4) Through observing micro structure, we can find the fast-growing china fir's cell is compressed just, cell cavity is smaller and cell wall has not been destroyed. In the course of compressed, compressed wood fixation is mainly because hydraxyl amount decrease, crystallization and hot decomposition and crosslink reaction in cell wall's composition. Besides, because of relaxation, wood must be compressed by stage and compressed wood must put for some time, it can reduce compressed wood rebound.