Effect of graphene oxide fibre surface modification on low-velocity impact and fatigue performance of flax fibre reinforced composites

Fatigue and impact resistance are essential performance indicators in structural biocomposites. Integrating multilayer and oxygen-rich graphene oxide (GO) crystals as a fibre surface modification or reinforcing agent in polymer matrix systems have been shown to enhance the interfacial strength and toughness of natural fibre composites. However, the state-of-the-art literature on the GO-modification of composites has focused mainly on their microscale and quasi-static mechanical performance. Here, the fatigue testing results showed that surface modification of flax fibres with GO reduces the slope of the S-N curve by 17% and promotes fibre pull-outs upon failure. Based on the in-situ impact damage analysis, the GO-modification delayed the impact damage initiation and prolonged the stable damage progression phase. The impact perforation energy was similar for modified and unmodified specimens. At kinetic energies below the perforation limit, the GO-modification suppressed the extent of fibre failure and endowed flax-epoxy specimens with better damping performance.