Study of sizing agents for carbon fibre-reinforced nylon-6 composites

Abstract

Unidirectional carbon fibre-reinforced polymers (CFRPs) are a popular choice of material in aviation, automobiles, and sporting goods due to their excellent mechanical properties such as high strength-to-weight ratio, stiffness and great fatigue resistance. More recently, to tackle CF-related environmental issues, thermoplastic-based CFRPs is an emerging class of composite material due to several advantages such as higher toughness and better recyclability. Nonetheless, the poorer CF/matrix physicochemical interactions typically result in weaker mechanical properties of the composite. Hence, this study has investigated how the structure of sizing agent impacts the interfacial properties of CF/PA6 composites. Waterborne polyurethane (WPU), a linear structured polymer, and acid-modified lignin, a hyperbranched macromolecule, have been employed as the sizing agents, respectively. The anionic-based sizing agents have been successfully deposited on the CF surface via electrophoretic deposition. Subsequently, fibre pull-out tests, mode II interlaminar fracture toughness (ILFT) tests were performed to evaluate the improvement in interfacial properties of the CF/PA6 composites.