Changes in the properties of light-irradiated wood with heat treatment: Part 3. Monitoring by DRIFT spectroscopy

This study investigated the effect of heat treatment on the color and DRIFT spectra of light-irradiated heartwood of Japanese cedar. The heat number of carbonyl groups caused by light-irradiation decreased with increasing relative humidity during treatment. Although two sub-bands of carbonyl groups changed with exposure to light, with heat treatment after light-irradiation the carbonyl band at 1,756 cm(-1) decreased more than that at 1,716 cm(-1). The change in the color of wood with light-irradiation is related to the degradation of lignin. However, it is assumed that the changes caused by heat treatment in unirradiated and irradiated wood are related not to lignin degradation but to low molecular compounds that are produced from lignin by light-irradiation and hemicellulose.