Effects of carbon fillers in thermally conductive polypropylene based resins

The thermal conductivity of insulating polymers can be increased by adding conductive fillers. One potential market for these thermally conductive resins is for fuel cell bipolar plates. In this study, varying amounts of three different carbon fillers (carbon black, synthetic graphite particles, and carbon nanotubes) were added to polypropylene. The effects of single fillers and combinations of the different fillers were studied via a factorial design. Each single filler caused a statistically significant increase in composite through-plane thermal conductivity at the 95% confidence level, with synthetic graphite causing the largest increase. All of the composites containing combinations of the different fillers caused a statistically significant increase in composite through-plane thermal conductivity. It is possible that thermally conductive pathways are formed that \u27link\u27 these carbon fillers, which results in increased composite thermal conductivity. Composites containing 80 wt% synthetic graphite had an in-plane thermal conductivity of 28.0 W/m.K, which is desired for bipolar plates (\u3e 20 W/m.K)