Effects of injection-molded conditions on the microstructure and mechanical properties of PC/LCP blends

The correlations of mechanical properties of injection-molded PC/LCP blends to the fibrillation and the molecule orientation of LCP domain were investigated. The following main results were obtained. (1) Although PC/LCP blends are immiscible, LCP domain will easily get into fibrillation and will show higher molecular orientation for the high melt viscosity of PC; therefore, the tensile strength of PC/LCP blends is improved. (2) Since the increase of injection-molding speed causes an improvement in the molecular orientation of LCP fibril in the intermediate layer and a declination in the molecular orientation in the core layer, the tensile strengths of PC/LCP blends did not change so much. (3) When the specimen thickness decreases, the ratio of LCP fibril with high molecular orientation increases and then the tensile strength of the blends has improved greatly. (4) When the amount of LCP increases, the quantity of LCP fibril increases and the molecular orientation of LCP fibril in the intermediate layer improves also; it resulted in a rapid improvement in the tensile strength of PC/ LCP blends. (5) A synergism that the tensile strength of blend specimens of 2 mm in thickness shows a far higher value than the theoretical one given by the rule of mixture was demonstrated.