The synergistic effect of benzhydrylation and iodination of the flammability of alpha‐cellulose

Cellulose samples modified by iodination, benzhydrylation, and benzhydrylation followed by iodination were pyrolyzed to investigate the potential flame retardance of such treatments. Their effect on crystallinity, rate of thermal degradation, char production, and pyrolysis products was determined. Results indicate that in general the crystallinity index varies inversely with the percentage of substitution, rate of weight loss, and amount of residual char. Although the rates of weight loss of the substituted samples increased from 0.3%/min to 108%/min, depending on the type and percentage of substitution, the overall weight loss pattern of the treated cellulose was similar to that of the untreated samples. Of the three treatments, iodination appears to offer the best flame retardance in that the residual char is increased by a much larger factor for a given weight loss rate. On the other hand, addition of the benzhydryl to the iodinated sample decreases the char. All three treatments drastically reduce the number of degradation products of molecular weights lower than 150; untreated cellulose gave 59 components, whereas the substituted cellulose produced five major compounds: water, acetic acid, furfural, 5‐methyl‐2‐furaldehyde, and 1,5‐anhydro‐2,3‐deoxy‐β‐D‐pent‐2‐eno‐furanose. Of these, water and the furanose derivatives were the major components.