Effect Of Heat Treatment On Performance Of Populus Adenopoda Maxim. And Larix Spp.

In this research, Populus Adenopoda Maxim, and Larix spp. were heat treated by steam at temperature from 150℃ to 210 ℃, for duration of 2h,4h and 6h. The effect of heat temperature and duration on properties of heat-treated wood were studied, such as dimensional stability, mechanical properties and color change after heat treatment. Furthermore, several models have been established to predict product quality as a function of L* and mass loss. The main research results are summarized as follows:(1) Heat treatment can improve the dimensional stability of heat-treated wood significantly, and the effective is better with temperature rising and duration increasing. Anti-swelling efficiency and anti-shrinkage of two wood species both reach the maximum when heat treated at 210 ℃ for 6h. The air-dried volumetric anti-shrinkage ratio、 oven-dried volumetric anti-shrinkage ratio、air-dried volumetric anti-swelling efficiency and water saturated volumetric anti-swelling efficiency of Populus Adenopoda Maxim, are 58.98%, 55.80%.77.45% and 51.75% respectively; Those of Larix spp. are 55.75%、58.94%、 80.00% and 61.98% respectively.(2) After heat treatment, the decrease of bending strength in Populus Adenopoda Maxim. are 0.34-66.72%, the decrease of Larix spp. reach the biggest 68.57%; heat treatment has no obvious effect on modulus of elastic of Populus Adenopoda Maxim, while that of Larix spp. decline with the increase of treatment intensity and decline the most with a 44.92% fall; With the increase of temperature and duration, compression strength parallel to grain of two wood species both present increasing at first and then decreasing, The big decrease of compression strength parallel to grain in Populus Adenopoda Maxim, and Larix spp. are 19.38% and 30.15% respectively.(3) Lightness values are reduced in different degree after heat treatment, chroma values of two wood species both appear increasing firstly and decreasing gradually with temperature rising and duration extending. △C* of Larix spp. reach the maximum when heat treated at 190 ℃ for 2h, that is the brightest. The overall color change △E* of Populus Adenopoda Maxim. and Larix spp. are 3.09～50.00 and 5.19～35.46.(4) The mass loss of heat-treated wood increase gradually when temperature rising and duration extending. The biggest mass loss of Populus Adenopoda Maxim, and Larix spp. are 14.34% and 8.49% respectively, so under the same treatment, the mass loss of Populus Adenopoda Maxim. is higher than Larix spp.. After comprehensive analysis, the quality of heat-treated wood whose mass loss are not less than 2% are better and have a wider application range.