Initial degradation processes of cellulose at elevated temperatures revisited -- chemiluminescence evidence

摘要

The initial processes governing degradation of cellulose at elevated temperatures are re-examined. The influences of moisture, alkali-earth metal carbonates, and atmosphere at 180℃, were studied. The various effects were studied both conventionally, by determining the changes in the degree of polymerisation by viscometry, and by chemiluminescence measurements. The moisture initially contained in the sample was shown to have no effect on degradation in dry nitrogen although the chemiluminescence of moist samples is initially considerably higher. It was associated with production of singlet oxygen. On the other hand, presence of moisture in oxygen atmosphere enhances oxidation. Some initial degradation occurs during rapid heating and was attributed to mechanical degradation, though no chemiluminescent phenomenon could be associated with it. The degradation rates during the more advanced phases were shown to be related to the presence of earth alkali metal cations. It is suggested that complex forma- tion between a metal cation and glycosidic oxygen might play an important role in the degradation mechanism.