The Effects of Lignin and Hemicellulose on Thermal-Softening Properties of Water-Swollen Wood

To obtain more detailed information on the effects of lignin and hemicellulose on the thermal-softening properties of water-swollen wood, we investigated the dynamic viscoelastic properties of Japanese cucumber tree specimens from which lignin or hemicellulose had been extracted The specimens had different weight loss rates Their dynamic viscoelastic properties were measured in the temperature range from 5 to 95 degrees C The value of E' decreased markedly with increasing weight loss rate in every treatment The peak temperatures of tan delta for the lignin-extracted specimens were significantly shifted to lower temperatures as the weight loss rate increased On the other hand, tan delta of the hemicellulose-extracted specimens was shifted to higher temperatures after it remained unchanged at first When we take wood structure and the mechanisms of these treatments into consideration. the above results might suggest that the thermal-softening property of water-swollen wood, especially its thermal-softening temperature. is more greatly affected by changes in quantity and quality of lignin than by those of hemicellulose