Self-assembling of few-layer graphene onto glass fibers and strength enhancement mechanism of few-layer graphene-reinforced GFRP

To further enhance the mechanical strength of glass fiber reinforced plastics (GFRPs), various approaches have been proposed in which few-layer graphene (FLG) or graphene nanoplatelets (GNPs) are coated onto reinforcing fibers. However, because of the lack of intrinsic interactions between fibers and FLG, it is difficult to achieve uniform coatings using simple dip-coating methods, particularly within the interior of fiber bundles. In this study, negatively charged FLG was successfully fabricated and uniformly deposited onto glass fiber fabrics via electrostatic interactions. The FLG-coated fabrics were subsequently molded by a hand lay-up method to fabricate hierarchically reinforced GFRP composites. Mechanical properties were evaluated through flexural testing, revealing a maximum increase of 17.46% in flexural strength and 22.32% in fracture strain. Acoustic emission (AE) analysis of the damage process indicated that the graphene coating acted as a barrier layer, promoting cohesive failure within the matrix and deflecting crack propagation paths. This crack deflection increased the strain required for final fracture, leading to enhanced flexural strength. These findings demonstrate the effectiveness of electrostatically assisted FLG coatings for improving the mechanical performance of GFRP composites. These findings provide a scalable and low-cost route for interphase engineering of GFRP laminates toward improved structural durability.