Assignment of DSC thermograms of wood and its components

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.