Abstract:

Eucalyptus timbers were treated through vacuum heat treatment method for 4 h at five different temperatures (160, 180, 200, 220 and 240 ℃). The surface free energy of untreated and heat-treated wood was studied using contact angle method, and during the heat treatment procedure, the chemical change of wood was analyzed by Fourier transform infrared spectroscopy(FTIR). In addition, the weight loss ratios of different temperature heat-treated wood were also analyzed by thermogravimetric analyzer. The results showed that compared with surface free energy of untreated wood(50 mN·m^-1), the surface free energy of heat-treated wood at 240 ℃ （32 mN·m^-1）was higher and that of heat-treated wood at 160 ℃(46 mN·m^-1) was lower. According to FTIR spectra of untreated and heat-treated wood, the number of polar carboxyl group of heat-treated wood was decreased. And when the heat-treated temperature was lower than 180 ℃, the weight loss ratio was about 1%, and as the heat-treated temperature exceeded 180 ℃, the weight loss ratio decreased twice or so by the temperature increasing 20 ℃ each time.

Key words: Eucalyptus pellita, heat treatment, surface free energy, FTIR analysis, thermogravimetric analyzer