Gaseous decomposition products from wood degradation via thermogravimetric and fourier transform infrared analysis during thermal modification of beech and pine woods

Wood thermal modification is an environmentally friendly method used to improve wood characteristics, and its degradation mechanism directly influences its application in construction, building, and home decoration. Combined thermogravimetry and Fourier transform infrared (TG–FTIR) studies were conducted to evaluate the hardwood and softwood on-site at 160 °C and 220 °C. The results indicated that the mass loss rates (MLRs) for both hardwood and softwood samples decreased over time and ultimately became constant. The total mass loss increased with an increase in temperature. The total mass loss was about 3% at 160 °C, and about 4.7% to 6.5% at 220 °C. Decomposition also occurred much more easily in the hardwood than in the softwood. More species of gas products were emitted from hardwood than softwood, and the number of species of gas products increased with an increase in temperature and processing time. The FTIR spectra of softwood were similar, whereas those of hardwood were remarkably different at different temperatures. Water and alcohol were generated from both the hardwood and softwood, whereas contents of these gaseous products were visible in hardwood decomposed at 220 °C during the thermal treatment. Ketones, ethers, acids, and aromatics were found in both hardwood and softwood, whereas CO2 was only found in the hardwood that underwent thermal treatment.