Impact of heat treatment on chemical composition of Chinese white poplar wood

Using a heating device with an inside content of oxygen of less than 2%,Chinese white poplar(Populus tomentosa Carr.) specimens were heat-treated at temperatures ranging from 170℃ to 230℃ for periods lasting from 1 to 5 h.Relationships between the chemical composition of heat-treated wood and treatment conditions were investigated.The results show that the amount of holocellulose and α-cellulose decreased,but that of lignin increased with increases in temperature and time during the heat treatment.Compared to the heating time,the heating temperature had a greater effect on the amounts of chemical composition.The critical condition for the marked changes in the amount of holocellulose and α-cellulose is the heating temperature of 200℃ for a period of 2 h.Using Fourier Transform Infrared Spectroscopy(FT-IR),the analysis indicated that the intensity of the characteristic absorption peaks of cellulose and hemicellulose decreased and those of lignin increased as a function of increasing temperature and time.Based on our experimental data,regression models were developed to predict the change of chemical composition(holocellulose,α-cellulose and lignin) for different temperatures and times.