3-4-4 Thermal reactivities of hemicellulose and cellulose in beech and cedar wood cell wall

Abstract

Xylan and glucomannan are the typical wood hemicelluloses, but the compositions are different depending on the species; xylan is the major hemicellulose in hardwood, whereas the contents of glucomannan are much greater in softwood. In the present study, thermal reactivities of polysaccharides in beech (hardwood) and cedar (softwood) cell wall were evaluated by comparing the reactivities with isolated polysaccharides. The reactivities were evaluated by obtaining the hydrolysable sugars remaining in the heated residues. As a result, cell wall ultrastructure had a significant effect on the reactivities of hemicellulose and the influences were different for cedar and beech. With these reactivities, thermogravimetric analysis (TGA) data were explained; although different shapes of DTG curves of softwood and hardwood are believed to originate from the reactivities of hemicellulose, the present results rather suggest the cause of different cellulose reactivities.