Fabrication Process and Characterization of Conductive Composite for PEFC Bipolar Plates

Abstract

Carbon reinforced conductive polymer composites were fabricated by the compression molding technique. Conductive fillers (graphite powder, carbon black and carbon fiber) were mixed with an epoxy resin to impart electrical property in composites. The ratio of graphite powder/carbon black/carbon fiber as well as fillerlresin was varied to investigate electrical property of cured conductive composites. In this study, carbon/graphite filled conductive polymer composites with high filler loadings (>60wt.%) were manufactured to accomplish high electrical conductivity (> 100S/cm). Graphite powder was the main filler to increase electrical conductivity of composites by direct physical contact between graphite powders. While high filler loadings are needed to attain good electrical property, the material becomes brittle. So carbon fiber was added to compensate weakened mechanical properties. Carbon black was dispersed in the epoxy resin to obtain the additional increase of conductivity by using very low percolation threshold. The electrical conductivity of composites was controlled with varying the amount of graphite powder, carbon black, and carbon fiber. The optimum molding pressure according to filler was proposed experimentally. And the behavior of carbon black in conductive composites with high filler loadings was proved through analyses of manufacturing condition.