A Critical Study of Selected Formaldehyde-Cross-linked Cotton Celluloses by Sol-Gel Analysis and by Distention-Index Analysis

Abstract

Cotton celluloses selected for pronounced differences in crystallinities and accessibilities have been cross-linked by the vapor-phase deposition of formaldehyde under conditions previously shown to cause different degrees of molecular degradation. The products at various levels of bound formaldehyde have been analyzed for sol and gel fractions and for degree of distention of the gel fraction in cupriethylenediamine hydroxide. The results of these analyses provide quantitative information on the gross uniformity of distribution of cross linkages in the fiber structure of the celluloses, the uniformity of the distribution of cross linkages along the molecular chains of the cellulose, and the ratio of chain scission to molecular cross-linking in the cross-linked compositions. These analyses can now be applied with greater confidence to obtain useful information on cross-linked celluloses, despite the heterogeneity of phases in the cross-linking reactions and the crystallinity of the cellulose.