Degradation of Cotton Fibers and Yarns by Heat and Moisture

Strength and elongation measurements were made on single cotton fibers and on yarns which had been subjected to various temperatures from 110° to 162°C and various moisture conditions from 3% R.H. up to saturation for periods of heating from 2 to 128 hrs. Moisture contents and degrees of polymerization were also determined, the latter being used to calculate cellulose chain rupture. The simultaneous reduction in strength and elongation at break indicates that heat degradation weakens fibers by creating or intensifying weak points along the fiber. An equation similar to that derived by Sippel, relating fiber strength loss to time of heating and percentage of cellulose links broken, is discussed. Yarn strength, although not as readily affected by heat degradation as fiber strength, follows a similar pattern.