Effect of graphene oxide nanosheets on the mixed mode I/II/III fracture toughness of polymer nanocomposites

Abstract

This paper deals with the improvement of fracture properties of epoxy nanocomposites using graphene oxide (GO) nanosheets. Epoxy/GO samples were fabricated in the form of compact tension shear (CTS) at filler contents of 0, 0.25 and 0.5 wt.%. Using Arcan fixture and an out-of-plane fixture as well as by varying the loading angle, a full combination of fracture modes (I/II/III) was created to evaluate the effect of nanofiller on fracture toughness. It was observed that the fracture toughness of the samples in all cases was significantly increased by the addition of GO. The highest effectiveness was achieved by the addition of 0.25% GO when the samples were tested under the combined mode I/II and pure mode III, which resulted in a 69 and 65% increase in the fracture toughness of the epoxy system, respectively. Also, a microstructural analysis using scanning electron microscopy (SEM) showed how GO prevented crack propagation in the composite. Microstructure analysis was also performed using scanning electron microscopy (SEM), which showed how GO inhibits crack propagation in the nanocomposite. The fracture mechanisms caused by the addition of GOs, including crack deflection, bridging, and secondary cracks, are presented and discussed based on SEM images. Therefore, GOs are able to provide effective fracture toughness to epoxy resins and are a highly efficient filler for use in epoxy-based nanocomposites.