Abstract :
Exotherms in the DSC analysis of wood and its components have been assigned using Akamatsu wood (Pinus densiflora). Analysis of wood powder indicated two exotherms at around 340 and 475°C. Among isolated components galactoglucomannan has a single exotherm at around 330–360°C, and other commercial amorphous polysaccharides are in the range of 300–370°C. Therefore, the transition at around 340°C in wood thermogram was considered to be due to polysaccharides. On the other hand, the temperature of the exotherm at 475°C in the analysis of wood was similar to that of a lignin–carbohydrate complex (LCC) and not to that of purified lignin (MWL) which was around 530°C. Removing hemicelluloses from LCC by hydrosulphuric acid or cellulase shifted the temperature to around 520°C. It is concluded that the exotherm in wood powder at around 475°C is due to a mixture of lignin and polysaccharides, in which the lignin is closely combined and complexed with the polysaccharides as in LCC.
