Effect of Vacuum Heat Treatment on Larch Earlywood and Latewood Cell Wall Properties

The aim of this study was to evaluate the hygroscopicity and nanomechanics earlywood (EW) latewood (LW) larch after thermal modification under vacuum conditions. Wood samples were heat-treated in a atmosphere at 180–220 °C for 6 h, then their cell wall properties observed using dynamic water vapor sorption (DVS), imaging Fourier-transform infrared (FTIR) microscopy, nanoindentation. results showed that heat treatment reduced EW LW increased hysteresis between adsorption desorption branches isotherm. Compared with EW, temperature had more pronounced influence on LW. Hailwood-Horrobin model found accurately fit experimental data. Imaging FTIR microscopy revealed degradation hemicellulose, cross-linking, condensation reactions, redistribution lignin wall. elastic modulus walls first decreased as increased; increase intense than EW. Cell hardness also markedly treatment. Our analysis suggests decreases alters chemical composition distribution walls, thus improving wood mechanics.