Effects of Sodium Hydroxide and Liquid Ammonia Treatments on Shape Changes of Cross-Sectional of Cotton Fibers Due to Swelling

Abstract

The cotton fabrics treated with formaldehyde vapor show high wash and wear (W&W) properties, but poor tensile strength as compared with the resin treated fabrics. This property is expected to be improved by liquid ammonia pre-treatment before the treatment with formaldehyde vapor. In this study, from a practical viewpoint of formaldehyde vapor treatment of cotton fabrics, the microscopic and macroscopic strain relaxation along the cross sectional direction of cellulose fibers by the pre-treatment with liquid ammonia, sodium hydroxide and sodium hydroxide/liquid ammonia were examined in terms of crystallinity, crystalline transition (microscopic uniformity index), barium activity number(amorphous content index) and aspect ratio of cross section of a fiber(macroscopic index). It was found that all examined pre-treatments bring about considerable changes in fine structural properties, but the liquid ammonia pre-treatment is superior to the other pre-treatments. This is due to the fact that the liquid ammonia pre-treatment brings about a uniform strain relaxation of cellulose fibers.