Effects of two- and three-dimensional graphene-based nanomaterials on the fatigue behavior of epoxy nanocomposites

Abstract Epoxy resins and their derivatives, such as composites and epoxy adhesives, are widely used in various industries. However, epoxy resins have low performance against dynamic loading and crack propagation. Graphene-based nanomaterials can improve the mechanical performance of polymeric composites because of their appropriate mechanical properties and high surface area. This study aimed to investigate the effect of Two-Dimensional Graphene Oxide (2DGO) and Three-Dimensional Nitrogen-Doped Graphene (3D(N)G) nanomaterials on the fatigue behavior of epoxy resin. 2DGO was produced by the modified Hummer’s method and 3D(N)G was synthesised by hydrothermal process, followed by freeze-drying. Nanocomposite specimens were prepared by adding 0.1 wt.% nanomaterials to epoxy resin. Tensile properties were analysed using the static tensile test. The tensile strength of epoxy resins reinforced with 2DGO and 3D(N)G improved by 16% and 19%, respectively. Subsequently, tension–tension cyclic fatigue tests with 0.1 stress ratio were conducted on pure epoxy, 2DGO/epoxy, and 3D(N)G/epoxy nanocomposites. Due to the addition of graphene-based nanomaterials, a significant enhancement in fatigue life of epoxy resin was obtained. For example, at a 35 MPa stress, fatigue life for 2DGO/epoxy and 3D(N)G/epoxy nanocomposites increased by 143% and 236%, respectively, compared to that of pure epoxy. Fractographic analysis revealed that the incorporation of 3D(N)G in the epoxy resin causes the formation of microcracks and resistance to devastating fatigue cracks in the early stages of their formation. Moreover, the high specific surface area and relatively strong bonding of 3D(N)G with the resin are the secondary factors in preventing crack prorogation and higher energy absorption during the fatigue process.