Dilute acid-hydrolized cotton cellulose An electron diffraction study

Summary

A comparative morphological investigation by electron diffraction analysis was carried out on samples of cotton cellulose from different stages of dilute-acid-catalysed hydrolytic degradation reactions. Within the range from $\overline {DP_n }$ 13000 (native material) to 500 only a gentle decrease of the relative crystallinity was observed. For $\overline {DP_n }$ below 500 the crystallinity decreases much faster, together with a simultaneous marked increase in paracrystalline lattice distortion and the show up of crystallographic evidence for a new cellulose phase which became better defined as degradation proceeded. A clearly defined parallel can be established between the different kinetic stages of the degradation reaction and the degree-of-polymerization dependence of the morphological features. The resulting evidence is at odds with the traditionally held views about the effects of acid hydrolysis of cellulose on its morphological fine structure.