Abstract
Vapor grown carbon fiber (VGCF) is a new kind of carbon fiber, which has outstanding properties such as high mechanical strength and electrical conductivity. We studied injection molding of polystyrene (PS) including VGCF as a filler and compared with the composites molded under the same conditions in which conventional carbon fillers were filled. As a result, the volume resistivity of VGCF/PS composite was 2.1 × 10^3 Ω・cm when the VGCF concentration was 6.7 volume percent. The resistivity was significantly lower than that of the composites which conventional carbon fillers were filled. The volume resistivity of CB/PS composite linearly dropped, whereas that of VGCF/PS composite dropped significantly between 3 and 4 volume percent and after which it linearly dropped. In addition, the resistivity of the composite decreased when the flow velocity during injection process was slow. The mechanical properties of the composites were almost constant in the VGCF concentration range from 0 to 12 volume percent.
