STRUCTURE AND PROPERTIES OF INJECTION-MOLDED BLENDS OF LIQUID-CRYSTALPOLYMER (40-PET 60-PHB) WITH POLY(BUTYLENE TEREPHTHALATE)

Blends of a poly(butylene terephthalate) (PBT) and a liquid crystallin e polymer (LCP) were prepared in a single screw extruder. The LCP used was a liquid crystalline copolyester of 40% polyethylene terephthalat e with 60% p-hydroxybenzoic acid (40 PET/60 PHB). Specimens for mechan ical testing were prepared by injection molding. Rheological, morpholo gical, microstructural, and mechanical properties were investigated by capillary rheometry, polarized light microscopy, x-ray diffractometry , and a tensile tester, respectively. For the LCP content higher than 5 wt. % a significant decrease of the viscosity was noted. The morphol ogy of the dispersed LCP phase varies between droplets and oriented fi brils. The degree of crystallinity of PBT and the crystal sizes were f ound to be affected by LCP addition. The tensile mechanical behavior o f the PBT + LCP blends war; also found to be affected by their composi tions. The elasticity modulus and the parameter of elasticity anisotro py monotonically increase with the LCP content. are strain at break sh ows a drastic decrease for the blends containing more than 10 wt. % LC P. The long-term creep test shows that the creep compliance decreases noticeably when the LCP content increases.