Injection Molding of Polystyrene Matrix Composites Filled with Vapor Grown Carbon Fiber

Abstract

Vapor grown carbon fiber (VGCF) is a kind of carbon nanotube, which has outstanding properties such as high mechanical strength and high electrical conductivity. In this study, injection molding properties of polystyrene (PS) filled with VGCF and evaluation of mechanical and electrical properties are discussed in comparison with composites in which conventional carbon fillers were filled. As a result, volume resistivity of VGCF/PS composites dropped significantly between VGCF concentration of 3 and 4 vol.%. Resistivity of the composites filled with VGCF was 1.2×10² Ω·cm when VGCF concentration was 11.6 vol.%. The resistivity was significantly lower than that of composites which were filled with conventional carbon fillers. The conductivity change due to volume fraction of VGCF was discussed using the thermodynamic percolation model. The elastic modulus slightly increases with increasing VGCF concentration, whereas the tensile strength slightly decreases in the VGCF concentration in the range from 0 to 12 vol.%.