Effect of graphene oxide size on interlaminar shear strength of glass fabric/epoxy composites

Graphene oxide (GO) has been widely used as nano-modifier for improving mechanical properties of polymers. However, the effect of GO size has not been examined yet on interlaminar shear property of glass fiber/GO-modified polymer composites. In order to efficiently enhance the interlaminar shear property of glass fabric/epoxy (GF/epoxy) composites, an epoxy resin was first modified by GO with different sizes and the modified epoxy was then used to manufacture the GF/epoxy composites by a press molding process. Due to its unique wrinkle morphology and functional groups, large GO acts as a 'bridge' to efficiently improve the interfacial adhesion between glass fibers and epoxy resin. The results indicate that at low GO contents (<= 0.1 wt%), the interlaminar shear strength (ILSS) of the GF/epoxy composites increases with increasing the GO size. Moreover, the ILSS of the composites firstly increases and then decreases with increasing the GO content. The microstructural characterization of the composites implies that the excess amount of GO might yield agglomeration and would then cause stress concentrations, resulting in the decreased ILSS of the composites. The optimal modifying efficiency in the ILSS with the 83.7% improvement was achieved by introducing the large GO with the dimension of 129.6 mu m at the 0.05 wt% content.