Optimized dispersion and multidimensional mechanical property enhancement mechanisms in reduced graphene oxide nanosheet reinforced epoxy composite coatings

Abstract

This study systematically investigates the impact of reduced graphene oxide (RGO) nanosheet content on the mechanical and adhesion properties of RGO/epoxy resin composites. The performance of these composites as coatings, adhesives, and bulk materials was comprehensively evaluated at various RGO nanosheet concentrations (0 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, and 1 wt%) using scratch tests, lap shear tests, and tensile tests. Additionally, analytical methods including SEM, Raman spectroscopy, and FTIR were employed to assess RGO nanosheet dispersion, interfacial bonding strength, and the composites' failure mechanisms. The results demonstrated that low RGO nanosheet contents (0.05 wt% and 0.1 wt%) significantly enhanced the fracture toughness and adhesion strength of the composites through mechanisms such as microcrack formation, crack pinning, and crack deflection. At 0.1 wt% RGO nanosheet, the composite exhibited optimal mechanical properties, showing the highest hardness, scratch resistance, and lap shear strength. This was attributed to the uniform dispersion of RGO nanosheet and strong interfacial bonding achieved through hydrogen bonding and physical cross-linking. In contrast, higher RGO nanosheet contents (0.5 wt% and 1 wt%) led to agglomeration, which reduced interfacial compatibility, created stress concentration areas, and promoted crack propagation, thus decreasing the composites' toughness and adhesion properties. Overall, the study suggests that controlling the dispersion and concentration of RGO nanosheet is essential for achieving high-performance RGO/epoxy composites, offering valuable insights for the design of advanced composite materials.