Primary Reactions and Reaction Products

A number of experiments and observations have been made on various aspects of heating cellulosic materials at temperatures ranging from slightly above ambient conditions up to 250° (when rapid volatilization occurs). At the lower temperatures, it is difficult to draw a line of demarcation between the thermal degradation and the normal 

In the oxygen atmosphere (see Fig. 2), the degree of polymerization rapidly decreased in the first 24 hours and then became almost constant at a value of about 200, which corresponds to the size of the cellulose microcrystallites. In a nitrogen atmosphere, the degree of polymerization dropped much more slowly and there was no sign of leveling off after 96 hours. 

The proportions of carboxyl and carbonyl groups formed, in terms of milliequivalent per mole of D-glucose residue, are shown in Figs. 3 and 4. There was no evidence of carboxyl formation in nitrogen, 

Investigation of cotton linters, before and after thermal degradation in oxygen, showed no difference in the x-ray diffraction patterns. In 

According to Waller and coworkers, the loss of strength on heating the yarn in the presence of oxygen and 12 % of moisture is not uniform with time, and appears to go through three distinct phases. These are an induction period, an interval of rapid degradation, and, finally, a phase of rather slow deterioration. The existence of an induction period which increases as the temperature is decreased indicates that the reaction products accelerate the degradation process. The effect of the decomposition products, accumulated in 

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