MISCIBILITY AND MECHANICAL-PROPERTIES OF POLY(ETHER IMIDE) LIQUID-CRYSTALLINE POLY(ESTER IMIDE) BLENDS

As a part of continuous study to search for the high performance in si tu composite, this study examines the miscibility of liquid crystallin e poly(ester imide) (PEsI) with poly(ether imide) (PEI) and its effect on the mechanical properties and the morphology of the blends of thes e polymers. Liquid crystalline polymers (LCPs) were synthesized from t rimellitic anhydride and alpha,omega-diaminoalkane with 8, 10, 12 meth ylene groups. Thermal condensation of these diacids with 4,4'-diacetox ybiphenyl yielded the corresponding imides of thermotropic homopolyest ers. Optical polarized micrographs show that the synthesized poly(este r imides) have the smectic structures. Patial miscibility was observed from the shift of the glass transition temperature determined by diff erential scanning calorimetry. Increasing concentration of the liquid crystalline PEsI in the PEI/PEsI blends shifted the glass transition t emperature of the PEI phase to a lower temperature. Mechanical propert ies of the PEI/PEsI blends were changed with the number of methylene u nits in PEsI. Morphologies of the partially miscible system were found to be quite different from those of an immiscible system. Strong adhe sion between the matrix (PEI) and dispersed phase (LCP) was observed, but fine fibril formation was not possible due to the absence of smect ic-nematic transition.