Effects of Chemical Processing on Shrinkage Behavior of Warp Yarns in Sodium Hydroxide Solution

Abstract

The shrinkage kinetics of warp yarns ravelled from poplin fabrics at different stages of wet processing namely: after desizing, scouring (subjected to solvent scouring, open soda boiling, and pressure boiling), bleaching (mild and severe conditions), and mercerization in 24% (w/w) sodium hydroxide solution have been studied. Yarns from the desized fabrics show the longest induction period and the lowest shrinkage rate. After scouring by any one of the three methods, the induction period decreases by almost an order of magnitude, while the rate of shrinkage increases from a value of 0.0014% per second for desized yarns to as much as 0.06% per second for solvent scoured yarns. Subsequent processes namely, bleaching under mild or severe conditions and mercerization have only minor effects on the shrinkage behavior of the scoured yarns. In the case of the desized sample, bleaching leads to a considerable reduction in the induction period and an increase in the shrinkage rate.