The epoxy-based glass fibre-reinforced polymers (GFRPs) were fabricated by adding three different graphene derivatives: anthracite coal-derived graphene oxide (AGO), commercial-grade graphene oxide (GGO), and commercial-grade reduced graphene oxide (GrGO). The composites having varying concentrations of nanofiller (0.075–0.3 phr), were prepared with hand layup using vacuum-assisted infusion molding setup. The results of the mechanical tests revealed that the AGO-reinforced composites showed the highest improvement at a concentration of 0.1 phr, with an increase of 27.6% in impact resistance, 27.1% in flexural modulus, and 11.7% in tensile strength. However, GGO and GrGO showed higher contents of 0.2 phr for maximum improvement. Structure-property correlations were carried out using FTIR, EDS, XRD, TEM and SEM. FTIR analysis revealed an increased relative abundance of oxygen functional groups in AGO, while EDS analysis revealed a decreasing trend of oxygen content (AGO > GGO > GrGO). The presence of remaining nitrogen-containing heteroatoms as reported in previous studies on coal-derived graphene oxide, can increase interfacial interactions. XRD and TEM analysis revealed improved exfoliation at optimal concentrations of GO, fracture surface analysis revealed improved matrix-fibre interactions and efficient crack-deflection. The findings of this study confirm that coal-derived graphene oxide is a low-cost nanofiller material for high-performance structural composites.
Singh et al. (Wed,) studied this question.