Mechanical performance of the extruded blends of liquid-crystalline copolyester and modified polyphenylene oxide

Abstract

Polymer blends of modified polyphenylene oxide (PPO) and thermotropic polyester were prepared by extrusion followed by drawing. The morphology and mechanical properties of the blends were examined by scanning electron microscopy, static tensile tests and dynamic mechanical analysis. The static mechanical tests showed that the liquid-crystalline polymers (LCP) additions led to an increase in both modulus and tensile strength of the blends, while elongation at break was generally decreased. The magnitude of the reinforcing effect depended significantly on the LCP content, but also on draw ratio. The Tsai-Halpin equation was used to estimate the aspect ratio of LCP microfibrils. The storage modulus showed that the LCP phase tended to reinforce the PPO matrix over a wide range of temperature but not near the glass transition zone.