Studies on swelling of cotton fibers in alkali metal hydroxides. II. Influence of morphology and fine structure on tensile behavior

Cotton fibers varying widely in gravimetric fineness but having nearly same percentage mature fibers have been subjected to swelling in 4.5 N LiOH, NaOH, and KOH at room temperature and 0°C. The resultant changes in fine structure are analyzed by X‐ray diffraction and infrared absorption methods while variations in surface morphology are followed by scanning electron microscopy. Extent of swelling measured by changes in gravimetric fineness follows the order LiOH ≥ NaOH ≥ KOH, the exact gradation being dependent on the variety. Analysis of tensile data shows that whereas moderate swelling leads to an increase in tenacity at 3.2 mm gauge length, excessive swelling leads to a decrease of the same, the extent of decrease being a function of swelling. KOH treatment produced uniform swelling and gave better retention of T 0 and T 3 for all varieties. Tensile behavior after slack swelling in the various reagents could be interpreted on the basis of fine structural variations produced by them. However, the differential response of cottons to a swelling agent is explained by postulating variations in the packing of structural elements along the radii.