Enhanced Mechanical Properties and Fracture Toughness of Graphene/GO-Modified Glass Fiber Composites

This work systematically investigates the effects of graphene (Gr) and graphene oxide (GO) content (0.3–2.0 w t%) on the mechanical and fracture behavior of glass fiber composites. Tensile, compressive, flexural, interlaminar shear and Mode I/II fracture toughness tests reveal concentration-dependent performance trends. Gr and GO exhibit distinct optimal thresholds: under tensile/compressive loading, GO achieves maximum strength enhancement at 0.6 wt % (11.90% tensile, 25.67% compressive improvement), while Gr peaks at 0.3 wt % (7.24% tensile, 17.68% compressive improvement). Flexural and shear properties show non-monotonic behavior, with Gr demonstrating optimal enhancement at 1.0 wt % (3.39% flexural strength increase) and 0.6 wt % (3.70% interlaminar shear strength improvement), whereas GO consistently degrades these properties. Mode I fracture toughness (GIC) for Gr peaks at 1.0 wt% (54.9% increase), outperforming GO by 28.3% presumably due to its interfacial adhesion. Conversely, Mode II toughness (GIIC) is enhanced by GO (6.15% at 0.6 wt %) but reduced by Gr (18.2% decline). Agglomeration-induced stress concentration and interfacial debonding dominate performance degradation beyond critical thresholds. These findings establish a framework for tailoring glass fiber composites with balanced mechanical and functional properties for aerospace applications.