Enhancement of performance in flax/epoxy composites by developing interfacial adhesion using graphene oxide

Graphene oxide (GO) at different contents, ranging from 0 to 0.5 wt%, was exploited to develop the interfacial adhesion between matrix and fiber in flax/epoxy composites. A proposed mechanism, which was substantiated by Fourier transform infrared spectroscopy, demonstrated that GO, thanks to possessing oxygen-containing functional groups, acted as a coupling agent between epoxy matrix and flax fiber. As a result of the developed interfacial bonding between composite constituents, significant improvements in tensile strength (68%) and flexural strength (65%) of composites up to 0.3 wt% were recorded. According to X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations, all nanocomposites formed an exfoliated structure. Microscopic observations depicted a substantial decline in the total crack lengths of composites and also the rate of cracks formed at the interface of fiber and matrix. It was also found that thanks to the developed interfacial adhesion between epoxy matrix and flax fiber, major defects responsible for composite premature failure did substantially reduce. In low-velocity impact test, resultant nanocomposites showed enhanced peak loads and damage tolerance owing to a strong interfacial adhesion developed by GO presence. Scanning electron microscopy (SEM) images of the impact-fractured surface of nanocomposites showed the risk mitigation of catastrophic damages, with the in-clusion of GO, due to the efficient fiber adherence to the matrix.