Multi-step microwave reduction of graphite oxide and its use in the formation of electrically conductive graphene/epoxy composites

The multi-step MW reduction technique was developed in this study to obtain reduced graphene oxides; EG, RGO-1, and RGO-2 with MW irradiation time of 1, 2, and 3 min, respectively. Results of TGA, IR, and elemental analysis demonstrated that the degree of reduction of GO increased with increasing the MW irradiation time. Overall, 3 min of MW irradiation of GO in 3 steps was sufficient to obtain highly reduced GO (C/O ratio 10.38 by elemental analysis). The electrical percolation threshold of composites was observed as 1 wt% and 0.3 wt% for RGO-1 and RGO-2, respectively. Even at 0.5 wt% loading of RGO-2 in epoxy, the Tg value of the composite increased by 10 °C, indicating a strong interfacial interaction between graphene and epoxy resin.