PHASE-BEHAVIOR AND RHEOLOGY OF BLENDS CONTAINING POLYCARBONATE AND A THERMOTROPIC POLYESTER

The phase behavior and theology of binary blends of polycarbonate (PC) and a liquid crystalline polymer (LCP) have been investigated. The th ermotropic LCP employed was a semiflexible polyester synthesized by me lt condensation of t-butylhydroquinone and 4,4'-dichloroformyl-alpha,o mega-diphenoxyhexane. It shows a distinct nematic-to-isotropic transit ion in the pure state and in the blends. Results of DSC and optical mi croscopy indicate that the LCP is solubilized in the mixture for weigh t fractions of LCP less than about 0.05 and shows partial miscibility with PC over the rest of the composition range. The phase separation i s considered to be driven by both isotropic and anisotropic interactio ns between constituent chains. Dynamic oscillatory measurements show t hat there is some interaction between the separate isotropic and aniso tropic phases, with complex viscosities of the blends being intermedia te between those of pure components and showing significant deviation from a logarithmic rule-of-mixtures. (C) 1996 John Wiley & Sons, Inc.