Co-curing effect of imidazole grafting graphene oxide synthesized by one-pot method to reinforce epoxy nanocomposites

Uniform dispersion of carbon nanomaterials in epoxy matrix is the most fundamental prerequisite to produce epoxy composites with high mechanical strength and high toughness. In order to enhance the interaction between graphene oxide (GO) and epoxy resin, imidazole (MZ) was introduced to GO covalently through isophorone diisocyanate (IPDI) up to the grafting ratio of 31 wt% in this work by one-pot method. This modified GO, GO-IPDI-MZ was capable to cure the diglycidyl ether of bisphenol-A epoxy completely at addition of ca. 33.3 wt%, showing a smooth exothermic peak with a maximum at 182 °C. To avoid aggregation of GO at so high content, the epoxy was co-cured by GO-IPDI-MZ together with 4,4′-diaminodiphenylmethane (DDM), and the cured epoxy composites exhibited maximum tensile strength, flexural strength, impact strength, and thermal conductivity when containing 0.80 wt% of GO-IPDI-MZ. SEM, X-ray diffraction, and thermogravimetry were used to investigate the structure and thermal stability of the cured epoxy composites. This research provides a new approach to disperse GO uniformly in epoxy and to enhance epoxy composites simultaneously by co-curing of curing reagent grafted GO.