Study On Super Temperature Heat Treated Poluar Wood

The thesis take fast-growing poplar as experiment material ,based on documents and prior preparation,studied the effects of different temperatue,time on properties of heat treatment poplar, the result are as follows:1.The temperature of heat treatment higher and the time longer, weightless rate higher accordingly too. The treated wood's dimension shrinkage ratio in radial and tangential direction become higher as the treat temperatue higher and the time longer,the dimension shrinkage ratio of radial direction and tangential have a good linear regression, the dimension shrinkage ratio of tangential is by two times higher than of radial. The heated wood's weight loss alsohave a good linear regression with dimension shrinkage ratio of radial direction and tangential.2. The treated wood's EMC and water absorption become lower as the treat temperature higher and the time longer. In these nine kinds of heat treatment, three indexes of MEE,ASE in radial and tangential direction have improved in various degree,the indexes improved mainly because some amylase of hemicellulose dissociate to furfurol and some outcome of glucide, under the function of heat, these materials canpolymerize in to polymer that insoluble in water,in addition crystallinity of treated wood have declined in a certain degree compare with untreated wood.3. The treated wood's compressive strength parallel to grain decreased as the treat temperatue be higher when the treat temperature were160℃and 180℃, but the lowest decrease degree happened when treat time is 2 hours at the temperature of 200℃; The treated wood's MOR,MOE,impact bending become lower as the treat temperature higher and the treat time longer when the treat temperature exceed 180℃,the degree of reduce become remarkable.4.Compared with untreated wood, treated wood's lightness index L* decreased, the red-green index a* and the yellow-blue index b* increased in various degree, the total color difference△E* increased as the treat temperature higher and the time longer, The surface gloss of group c increased a little but group F and I had decreased a lot Compared with untreated wood; treated wood's contact angle increased a lot compared with untreated wood, proved wooden surface free energy of treated wood drop to some extent;total colour difference of the untreated wood is obviously bigger than the treated wood after exposed under sunlight for 180 hours,but treated wood also has prominent color change, so it had better carry on the preconditioning before the treated wood be employed outdoors.5. Compared with untreated wood ,the treated wood's infrared spectrum form is basically the same, have part of peaks skew and absorb intensity changed only, proved heat treatment wood's main internal chemical composition changed gently. It's good explained the mechanism of impact on wood of heat treatment.