Surface modification of aramid fibres by graphene oxide nano-sheets for multiscale polymer composites

Aramid fibre–graphene oxide (GO) multiscale reinforcement fibres were prepared by a novel technique where a plasma co-polymerized functional primer coating was initially applied on fibres followed by chemically attaching GO unilamellar sheets to the functionalized surface of the fibres. The functionalized fibres were immersed in purified GO aqueous suspensions at 60 °C under two pH conditions (slightly acidic GO suspension at pH 6 and alkaline ammonia water GO suspension at pH 9). The multiscale hybrid fibres were characterized by XPS, FTIR, Raman spectroscopy, SEM, AFM and tensile measurements. The fibres treated in alkaline ammonia aqueous suspension showed better strength and adhesion characteristics. The mean tensile strength value for the modified fibres showed an improvement over 7.9% whereas the interfacial shear strength in modified fibre–epoxy model composites, as determined by micro-bond technique, improved by 44.68%.