(180z) Electrical Conductivity of Carbon Filled Liquid Crystal Polymer Composites for Fuel Cell Bipolar Plate Applications

Electrically conductive resins are needed for use as fuel cell bipolar plates. Often, bipolar plates are manufactured with a single type of graphite powder in a thermosetting resin. In this research, varying amounts of three different electrically conductive carbon fillers (carbon black, synthetic graphite, and carbon fiber) were added to Vectra A950RX liquid crystal polymer in various concentrations. The maximum filler volume fraction was 12% for carbon black, 65% for synthetic graphite, and 45% for carbon fiber. The resulting single filler composites were tested for electrical resistivity (1/electrical conductivity).

In addition, the effects of single fillers and combinations of different carbon fillers were studied via a factorial design. The results indicated that for the composites containing only single fillers, synthetic graphite, followed by carbon fiber, cause a statistically significant decrease in composite electrical resistivity.

Furthermore, three models were developed for the single filler composites: Mamunya, Additive, and Global Effective Media (GEM) models. The model results suggest that the Mamunya and Additive models yield better correlations with the single filler experimental data. However, the GEM model can also be applied to predict the electrical conductivity of composites with multiple fillers. This was done for carbon fiber and synthetic graphite fillers with excellent agreement between model predictions and the experimental data.