Study on the interface toughening of particle/fibre reinforced epoxy composites with molecularly designed core–shell particles and various interface 3D models

Abstract

Poor interface toughening reduces the utilisation of particle/fibre-reinforced thermoset polymer composites in many engineering applications. Numerous studies have been performed on polymer and fibre component modifications, yet utilising fillers in epoxy is a promising way to improve interface toughness. Here, a molecularly designed core–shell particle (CSP) is introduced into the epoxy polymer to generate a strong interface through an epoxy coupling agent acrylate shell and styrene-butadiene rubber core. The nanocomposite material, in particular, has an excellent tensile strength of 166% and exceptional elongation of 245%; these properties further improve the interlaminar shear strength of 225% in carbon fibre-reinforced polymer composite. Moreover, CSP gives better shear effects and stress transferability to the fibre–matrix interface region. It was clarified systematically by developing a 3D micro- and macro-mechanical model from field emission scanning electron microscopy (FESEM) and surface fracture analysis. Meanwhile, results suggest that effective toughness is achieved by well-dispersed and void growth, filler-epoxy interaction and strong matrix-fibre interfaces. With these features, this study emphasises a way to analyse composite structures and fibre laminates which can help engineering design strategies for various applications.