Thermal Degradation of Wood and Its Constituents on Smoldering Combustion in Oxygen Atmosphere

抄録

Thermal degradation of wood has been studied by the measurements of oxygen consumption (O.C.) and weight loss (W.L.) for wood and its constituents (cellulose, xylan, and lignin) under isothermal condition in pure oxygen atmosphere in the range 160-260°C. Lignin consumed a large amount of oxygen even at 160°C, nevertheless its W.L. value was extremely small. On the ohter hand, O.C. as well as W.L. of cellulose and xylan increased remarkably above 220°C and 180°C, respectively. The plots of W.L. vs. O.C. for wood components, which were evaluated on the basis of the component weight ratio of 2:1:1, gave a straight line up to 200°C. The plots for wood coincided fairly well with the evaluated plots up to 200°C. Above 220°C, however, the plots of W.L. vs. O.C. of wood increased largely as compared to those of 200°C and a breaking point occurred at an exposure time of 4h at 260°C. IR spectral measurements for these systems suggests that autoxidation of the amorphous region, due to the presence of peroxide and OH radicals, must occur untill 200°C is reached, while above 220°C the oxidation and degradation prevail more definitively, where loosening and collapsing of the crystalline fibril region of wood occurs.