College of DuPage, Chemistry, Lombard, IL 60148
Several partially fluorinated hydrocarbon polymers have been screened to form composite films as components of bipolar plates for application in proton exchange membrane fuel cells (PEMFC). Various compositions containing these polymers and graphite were scouted to prepare conductive films of about 0.4 mm thickness. A methodology was also devised to adhere these composites to the stainless steel substrate using anchoring molecules. The most promising anchor was found to be 4-[2,2,2-Trifluoro-1-(4-{2-hydroxy-3-[4-(4-oxiranylmethoxy-benzyl)-phenoxy]-pro poxy}-phenyl)-1-trifluoromethyl-ethyl]-phenol both pre- and in-situ prepared from bis (4-glycidyloxyphenyl)methane and 4,4’(hexafluoroisopropylidene)diphenol. The composite films were consequently laminated on to 310S stainless steel plates using the anchors. These conductive composite coated plates showed excellent thermo-hydrolytic stability in boiling water for an extended period. In addition, resistance to delamination and corrosion were established by immersing these conductive plates in fairly concentrated H2SO4 for 10 days. Out of several compositions evaluated, initial results indicate that poly(chlorotrifluoroethylene) with 60 volume% graphite to be a superior composition. These preliminary results are encouraging and would have positive impact on the cost factor of fuel cell assembly without sacrificing performance.
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