Development of graphite/graphene/carbon nanotubes filled benzoxazine composites for bipolar plates in fuel cell applications

This research aims to develop bipolar plate from polymer composite to be used in proton exchange membrane fuel cells. The key properties of bipolar plates include high thermal conductivity, high electrical conductivity, high flexural strength and modulus, and low water absorption. The polybenzoxazine composites having three types of carbon derivatives i.e. graphite, graphene, and carbon nanotubes were prepared using a compression molder with a pressure of 15 MPa and a temperature of 200oC for 2 hours. The effects of carbon nanotube contents varying from 0-2wt% at an expense of graphite with constant content of graphene and benzoxazine at 7.5 and 16wt% respectively on properties of composites were investigated. With an incorporation of carbon nanotubes, relevant properties of the obtained composites increased. At 2wt% carbon nanotubes, storage modulus at room temperature of the samples was 11.4 GPa whereas glass transition temperature was 207oC. Moreover, the composites exhibited thermal conductivity of 21.3 W/m·K, electrical conductivity of 364 S/cm, flexural strength and modulus of 41.5 MPa and 49.7 GPa respectively. Such results indicated that the incorporation of carbon nanotubes could enhanced the properties of the composite to meet those requirement by Department of Energy, USA and confirmed that benzoxazine composites filled with graphite graphene and carbon nanotubes were such a great candidate as bipolar plate in fuel cells application.