Mechanisms of degradation of cotton and effects of mercerization-stretching upon the course of these mechanisms. V. Weathering

Abstract

Scoured ply cotton yarn was slack mercerized followed by restretching the cotton yarn to 90–103% of the original length in the mercerizing solution. The scoured and the mercerized cotton yarns were subjected to weathering for up to 14 months. Regardless of the cotton substrates, exposure to weathering was accompanied by an increase in copper number, decrease in both degree of polymerization (DP) and iodine sorption, and a loss in strength properties. No significant change in the carboxyl content of scoured and mercerized cottons could be observed after weathering. However, mercerized cottons retained higher strength in spite of higher degradation as compared to scoured cotton. This was interpreted in terms of removal of structural imperfections or weak links in cotton during the combined as swelling and stretching process evidenced by interrelationships between tenacity and percentage of bonds broken, as well as tensile strength and DP together with measurement of the average distances between crystallite centers in scoured and mercerized degraded cotton.