Effects of surface-modification on properties of Graphene/Epoxy composites

Among all the carbon fillers, graphene has attracted tremendous research interest for its special two-dimensional and single-atom-thick structure. High electrical, mechanical and optical properties of graphene have been proved. By adding graphene as filler into polymer, it is possible to achieve a new composite with unique physical, electrical and thermal properties. In this paper, epoxy/graphene composites with or without silane coupling agent surface modification have been prepared using sol-gel method. Researches have proved that graphene can improve the properties of composite at a very low loading content. The content of graphene in this paper was selected as 0.1wt%. Dispersion of graphene in epoxy was observed by polarizing optical microscope (POM) and scanning electron microscope (SEM). Results proved that after surface modification, graphene was dispersed better in epoxy. Thermal properties of epoxy were obtained by means of differential scanning calorimetry tests (DSC). Results showed that even with very low content of graphene, the glass-transition temperature of composite increased, indicating better thermal properties. Conductivity in various electric fields of composites and dc surface flashover voltages were obtained, showing that though the surface conductivity of composite increased, surface flashover properties didn't decrease. Graphene/epoxy composites with excellent properties were expected to be a potential candidate for smaller insulation system.