Thermal,Structural,and Mechanical Properties of Strands of Blends of Liquid-Crystalline Copolyester and Copolyesteramide with Poly(ethylene terephthalate)

Abstract

Rheological, thermal, structural, and mechanical properties of strands of two kinds of blends containing a liquid-crystalline copolyester (LCP-A) and a liquid-crystalline copolyesteramide (LCP-B) with poly(ethylene terephthalate) (PET), respectively, were investigated using differential scanning calorimetry, x-ray diffraction measurements, scanning electron microscopy, and tensile testing. The apparent melt viscosity of LCP-A/PET blends was slightly smaller than that of LCP-B/PET blends. Thermal behaviour of the two LCP/PET blends showed that both LCP-A and LCP-B are incompatible with PET. The cold crystallization temperature and the phase transition heat of the PET component became a little lower with increasing a draw ratio of the strands only for LCP-A/PET blends. The LCP-A component formed oriented fibrils more easily in the strands of blends below 50% LCP-A content even at low draw ratios, while the LCP-B one tended to form many spherical or elliptical structures. As a result, the strands of LCP-A/PET blends had better tensile properties than those of LCP-B/PET ones in this work.