MERCERIZED AND CROSS-LINKED COTTON YARNS .2. EFFECT OF STRETCHING DURING MERCERIZATION ON PHYSICAL-PROPERTIES AND DEGRADATION OF CROSS-LINKED YARNS

The effect of varying degrees of stretch on various cotton yarn properties during mercerization was studied. Scoured cotton yarns were slack mercerized in an aqueous solution of caustic soda, then restretched to 90%, 94%, 96%, 100%, and 103% of the original lengths. There was a considerable increase in strength and a decrease in elongation. Mercerized and scoured yarns were subjected to a crosslinking treatment with formaldehyde using the Form W and D processes. The mercerized yarns had a higher formaldehyde content but retained higher strength compared to scoured crosslinked yarn for both crosslinking processes. The mercerized yarn samples stretched to 103% showed the highest strength retention values after crosslinking for both the processes compared to other yarns. The scoured yarns crosslinked by the Form D bath process showed very low tenacity retention (42%), while the yarn mercerized and stretched to 103% showed very high tenacity retention (90%). The relationships between strength and various other properties are also discussed. The higher retention of tenacity in mercerized crosslinked yarn is attributed to the removal of weak points present in cotton and the more uniform structure capable of distributing stress along the fibers.