Surface Modification of Reinforcing Fibres for Enhanced Interfacial Properties in Polymer Composites

The mechanical integrity of fibre-reinforced polymer (FRP) composites is dependent on the adhesion of the constituents at the fibre-matrix interface, as it is the primary location for stress transfer and dissipation. Surface modification of synthetic and natural reinforcing fibres allows for the modulation of the interphase region to promote enhanced mechanical properties in FRP composites. The present research aimed to understand the effect of graphene oxide (GO), a two-dimensional nanomaterial, and polyether amine (PEA), an amine-terminated, aliphatic polymer, based fibre surface coatings on the interfacial adhesion of carbon/epoxy and flax/epoxy composites. GO nanomodification, applied via dip coating, improved the interfacial adhesion of carbon/epoxy composites by 28%, while maintaining the inherent carbon fibre mechanical properties. Subsequently, flax/epoxy composites experienced a 30% and 46% improvement in the transverse fibre bundle tensile (TFBT) strength and strain-at-failure, respectively, upon the application of a bi-layer GO/PEA coating, producing a toughening effect within the interphase region.