STRUCTURE AND PROPERTIES OF BLEND FIBERS FROM POLY(ETHYLENE-TEREPHTHALATE) AND LIQUID-CRYSTALLINE POLYMER

The structure and properties of the as-spun fibers of poly(ethylene te rephthalate)(PET) blends with a thermotropic liquid crystalline polyme r(LCP), Vectra A900, were studied in detail. The DSC results indicate that the LCP component may act as a nucleating agent promoting the cry stallization of the PET matrix from the glassy state but which inhibit s its crystallization from the melt due to the existence of an LCP sup ercooled mesophase. The effect of the drawdown ratio on the orientatio n of the as-spun blend fibers is highly composition-dependent, which i s mainly associated with the formation of LCP fibrils during melt spin ning. The modulus of the as-spun blend fibers has a significant increa se as the content of LCP reaches 10%, while the tensile strength has a slightly decreasing tendency. The mechanical properties of the as-spu n blend fibers could be well improved by heat treatment because of a s triking increase in the crystallinity of the PET matrix. (C) 1997 John Wiley & Sons, Inc.