Effects of low molecular weight liquid crystal blend with polycarbonates using various polymer processing instruments

Abstract

Concerned about the effects of low molecular weight liquid crystal (LCC) blend with polycarbonates that influence on the mechanical properties, thermal properties, morphology and molecular weight distributions of polymer blends. The two polycarbonates, having different weight average molecular weight (PC2600 and PC2405), were blended with LCC (CBC-33) at concentration about 0.2% by weight using an internal mixer, a single screw extruder and a twin screw extruder. The results showed that the operating torque of the internal mixer used when melting polycarbonate blended with LCC was reduced about 20%, the operating torque of the single screw extruder used when extruding polycarbonate blended with LCC was reduced about 83% and the operating torque of the twin screw extruder used when extruding polycarbonate blended with LCC was reduced about 51%. This phenomenon indicated that LCC could act as a viscosity modifier of polycarbonates. The mechanical properties were determined by tensile testing specimens from injection molding machine, the difference of tensile strengths and modulus of elasticities between pure polycarbonates and their blends were less than 10 percent for all mixing processes. The additions of small amount of LCC have slight effects on the morphology, thermal properties and molecular weight distributions of polycarbonates.