Novel reinforced polymers based on blends of polystyrene and a thermotropic liquid crystalline polymer
A thermotropic liquid crystalline polymer (LCP), when added to polystyrene (PS), can function as both a processing aid and a reinforcing filler. Thermal, rheological, and mechanical properties of the pure components and blends containing up to 10 percent LCP are reported. The LCP used is immiscible with PS, and when an extensional component of flow is present during processing, the LCP forms an elongated fibrous phase oriented in the flow direction. This oriented phase lubricates the melt, substantially lowering the viscosity. When the processed blend is cooled, the dispersed fibrous LCP phase is preserved in the solidified material. The LCP microfibers behave like short reinforcing fibers to improve the mechanical properties of the blend; for example, at an LCP concentration of 4.5 percent, the modulus is increased about 40 percent vs. pure PS.