MECHANICAL PERFORMANCE OF THE EXTRUDED BLENDS OF LIQUID-CRYSTALLINE COPOLYESTER AND MODIFIED POLYPHENYLENE OXIDE

Polymer blends of modified polyphenylene oxide (PPO) and thermotropic polyester were prepared by extrusion followed by drawing. The morpholo gy and mechanical properties of the blends were examined by scanning e lectron microscopy, static tensile tests and dynamic mechanical analys is. The static mechanical tests showed that the liquid-crystalline pol ymers (LCP) additions led to an increase in both modulus and tensile s trength of the blends, while elongation at break was generally decreas ed. 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 mod ulus showed that the LCP phase tended to reinforce the PPO matrix over a wide range of temperature but not near the glass transition zone.