Interface modification of PC/LCP in situ composites

Recently, polymer blends containing thermotropic liquid crystalline polymers (LCPs) and thermoplastics have attracted much research attention. The LCP phase, due to its inherent molecular structure and lower viscosity, with respect to the thermoplastic matrix, tend to develop fibrillar morphology with high degree of orientation in thermoplastic matrix under appropriate processing conditions. LCP, with high stiffness and high strength, not only reinforces the thermoplastic matrix, but also serve as processing aid in extrusion or injection molding due to its low melt viscosity. Commonly the LCP blends cannot attain their expected mechanical performance because of the poor miscibility between LCP and thermoplastics, which results in intrinsically weak interfaces. Work is being directed at improving the properties of polymer blends by modifying the interfaces and hence the mechanical properties by using compatibilizers. The concept of using a third component in compatibilizing the binary thermoplastic-thermoplastic systems has been extensively studied but not for thermoplastic/LCP systems. In this work, a bis-phenol A epoxy resin was used to modify the compatibility between polycarbonate (PC) and LCP during injection molding based on previous study [1]. Also, a curing agent 4-4' -diaminodiphenol sulfone (DDS) has been used, as a step towards in promoting the interfacial interaction, by opening the epoxy end groups to react with LCP