A STUDY OF POLYCARBONATE LIQUID-CRYSTAL POLYMER BLENDS

The morphology and the thermal and mechanical properties of blends of bisphenol-A polycarbonate (PC) with a wholly aromatic liquid crystal copolyesteramide (Vectra-B of Hoechst-Celanese) are discussed with reference to the conditions used for their preparation. The blends made by extrusion behave as mixtures of incompatible polymers: the dispersed liquid crystalline phase is more or less oriented in the extrusion direction and acts as a reinforcing filler for the PC matrix. The behaviour of the blends prepared in a batch mixer depends strongly on mixing time. A slight decrease in the mechanical properties (especially tensile strength and elongation) accompanies the morphological changes associated with a progressive improvement in the compatibility of the two polymers, which finally leads to an apparently homogeneous material after 45 min mixing at 2900-degrees-C and 150 rpm. These effects are interpreted in terms of chemical interactions taking place between the two components of the blends.