RHEOLOGY AND MORPHOLOGY OF COMPATIBILIZED POLYAMIDE-6 BLENDS CONTAINING LIQUID-CRYSTALLINE COPOLYESTERS

The theology, mechanical properties and microstructural development du ring capillary flow of maleic anhydride compatibilized polyamide 6 [PA 6(MAP)] blends containing liquid crystalline polymers (LCPs) were stud ied by means of the capillary rheometer, tensile test and scanning ele ctron microscopy (SEM). The LCPs used were Vectra A950, and a copolyes ter consisting of 60 mole percent p-hydroxybenzoic acid (PHB) and 40 m ole percent poly(ethyleneterephthalate) (PET). The rheological measure ments showed that the viscosity ratio between the Vectra A950 and [PA6 (MAP)] matrix is much larger than unity. This implied that the LCP fib rillation is unlikely to occur in the [PA6(MAP)] blends containing Vec tra A950 additions. However, SEM observations revealed that long and f ine fibrils are formed extensively in the matrix of [PA6(MAP)] polyble nds containing Vectra A950 content greater than or equal to 20 wt%. Co nsequently, the tensile strength of these polyblends appeared to incre ase with increasing LCP content, and deviated from the predictions of the rule of mixtures. On the other hand, the viscosity ratio between t he 60/40 PHB/PET and [PA6(MAP)] matrix is smaller than unity, thus fav ouring the formation of LCP fibrils. But, the SEM examinations showed that the LCP phase dispersed into porous and foamy structure in the ma trix owing to the decomposition of 60/40 PHB/PET polymer and PA6(MAP) during processing. In this case, the tensile strength of the [PA6(MAP) ] polyblends containing 60/40 PHB/PET polymer appeared to decrease sha rply with increasing LCP content. The correlation between the flow pro perties and LCP morphology was discussed. (C) 1997 Elsevier Science Lt d.