Effects of spinning and drawing conditions on the crimp contraction of side-by-side poly(trimethylene terephthalate) bicomponent fibers

The crimp properties in the melt-spinning and drawing processes of side-by-side bicomponent fibers with poly(trimethylene terephthalate)s (PTTs) of different viscosities were studied. Two PTTs of different intrinsic viscosities (1.02 and 0.92) were selected to make latent crimp yarn. The spinning and drawing conditions were changed to investigate the relation between the process conditions and crimp contraction. An orthogonal array was used to rule out the weak variables. The draw ratio, heat-set temperature, and portion of high-viscosity PTT were selected as variables having an effect on the crimp contraction. An analysis of the effects of the spinning and drawing conditions on the crimp contraction showed that the draw ratio was the most critical variable. Increasing the draw ratio caused a difference in the shrinkage between the two parts of PTT and caused the self-crimping of the bicomponent fibers. Although changing the heat-set temperature and the portion of high-viscosity PTT did not produce a dimensional change, the crimp contraction varied with those variables. As the heat-set temperature and the high-viscosity portion increased, the crimp contraction increased. (c) 2006 Wiley Periodicals, Inc.