Polymer grafted graphene oxide: For improved dispersion in epoxy resin and enhancement of mechanical properties of nanocomposite

Abstract In this work, poly(vinyl imidazole) (PVI) chains have been grafted from the methacrylate functionalized graphene oxide (GO) nanosheets surface via radical polymerization yielding nanocomposite PVI-g-GO. The homogeneous stable dispersion of PVI-g-GO in epoxy resin (EP) has been cured using triethylenetetramine (TETA) curing agent. In-depth structural characterization of resulting PVI-g-GO was carried out using Fourier transform infrared spectroscopy (FTIR), thermal gravimetrical analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The exfoliation and dispersion of PVI-g-GO sheets in the EP matrix was investigated by XRD and scanning electron microscopy (SEM). The kinetic parameters of the curing process were determined using non-isothermal Kissinger and Ozawa methods. The PVI-g-GO enhanced the curing rate via decreasing the activation energy (Ea) of the reaction. The mechanical properties of the nanocomposites were investigated by using tensile tests. Comparing with the neat EP, the tensile strength and modulus of the nanocomposite contains 0.25 wt% of PVI-g-GO increased 59.6% and 45.5%, respectively. The fracture surfaces were analyzed by SEM showing toughening structure with rough surfaces confirming the enhanced tensile strength. The thermal stability of the nanocomposites was investigated by using TGA and differential scanning calorimetric (DSC).