Oxidation of Formaldehyde Cross-Linked Cotton

Abstract

Cross-linking with HCHO appears to exert a highly stabilizing effect on cotton fabrics, which expresses itself in greatly lowered oxidation rates with NaClO at pH 7 and in a change in the oxidation mechanisms, bringing about a smaller yield of functional groups, an increase in oxidant consumed per chain scission, i.e., a smaller degradation and smaller losses in tear and burst strength upon oxidation. The main stabilization occurs for 0.3% to 0.9% bound HCHO, in which the largest increase in wrinkle recovery angle and the largest decrease in oxidation rates are observed, indicating that at this range interchain cross links are formed. Upon increasing the bound HCHO level from 0.9 to 2.0%, a relatively small further decrease in oxidation rate, a small, further increase in WRA, an insignificant increase in amount of oxidant per chain scission, but a drastic reduction in the number of functional groups per scission are obtained, indicating the formation of intra-AGU links. Most of the oxidation of the cotton at the 2.0% HCHO level appears to be associated directly with chain scissions occurring at the glucosidic C 1-C4 linkages, yielding aldehyde groups at C1 and ketone groups at C4. The nitration method for the determination of the D.P. was found to be applicable to HCHO-cross-linked cottons and straight-line relationships were obtained for tear strength versus 1/D.P. for cottons containing up to 0.9% HCHO.