Near infrared spectroscopic investigation of the thermal degradation of wood

In the present paper changes in the near infrared (NIR) spectra and color parameters of wood (Dalbergia sissoo) after thermal treatment are reported. The color change of the wood upon heating was analyzed by the CIELAB color parameters. The degradation of wood upon heating was determined by differential scanning calorimetery (DSC). Wood degradation involved from 50 °C to 80 °C changes in the amorphous region in cellulose took place, from 100 °C to 130 °C changes were observed in physically bonded water and from 150 °C to 160 °C degradation of hemicelluloses took place. The phase transition of cellulose took place at about 175 °C and changes in the crystalline region in cellulose were observed at 210 °C. The significant changes are observed in the lignin at elevated temperatures. The change in the color of the wood on increasing temperature is related to the degradation of hemicelluloses. NIR spectroscopy was found to be a powerful tool to determine the physicochemical structural changes in wood on heat treatment.