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Percolation threshold study of a plastic–elastomeric matrix based composite material for bipolar plates in proton exchange membrane fuel cells

Bipolar plate materials play an important role in designing a cost-effective fuel cell. This research aims to develop a polymer matrix based composite bipolar plate material for proton exchange membrane fuel cells. The polymers investigated are a vinyl ester resin (VER) and two elastomers including polyurethane (PU) and ethylene–propylene–diene monomer (EPDM). The VER alone and the blend of VER with either PU or EPDM makes the one-phase, one-phase blend, or two-phase blend matrices. These matrices will be incorporated within the conductive fillers including Cytec DKD carbon fiber (DKD), Asbury synthetic graphite grade 4012 flake (4012), and grade TC 307 high-surface flake (307). A percolation threshold study was conducted and two-phase blend matrix can achieve lower percolation thresholds. The composite material with 65 vol.% of two-phase bend matrix (60 vol.% VER and 40 vol.% EPDM), and 35 vol.% of conductive fillers (21 vol.% DKD, 5 vol.% 4012 and 9 vol.% 307) is found to have low electrical properties with improved mechanical properties.