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Expanded graphite /epoxy composites for bipolar plates applications

Abstract:

Appropriate conductive fillers and resin are important in the development of bipolar plates. This research aim the improvement of a graphite/epoxy composite as a potential material for conventional bipolar plates, based on the Department of Energy (DOE) requirements. The composites were prepared by molding compression at 100°C and 3500 psi with a post-cured process at 120°C. The synergistic effect of secondary fillers Carbon Black (CB) and Nano-99 (N99) with expanded graphite on the electrical conductivity were studied. A series of compositions using expanded graphite (EG) as primary filler and DGEBA epoxy resin cured with aliphatic amine. Adequate processing conditions were studied in order to get good dispersion with none or low solvent content. The compositions of secondary filler were varied as 0/5/10/15/20 percent in a constant 40% Graphite - Epoxy resin (w/w), where 10% CB exhibits higher electrical conductivity with 3.05× 10−2 S/cm. Weight compositions of graphite of 40/50/60/70 percent, maintaining 10% of CB, were studied comparing flexural strength and conductivity. At 70% conductivity is improved up to 18.5 S/cm, but flexural strength went down as 22 MPa. These data show a promissory carbon material to be manufactured for bipolar plates to use in PEM fuel cells.