Interlaminar shear properties of carbon fiber/nylon 6 composites reinforced with GO-modified waterborne polyurethane sizing agent prepared by in situ polymerization

To enhance the interfacial bonding of carbon fiber/nylon 6 thermoplastic composites, this study successfully grafted isophorone diisocyanate onto the surface of graphene oxide by leveraging the reactivity of isocyanate and hydroxyl groups. This modified graphene oxide was then grafted onto the waterborne polyurethane molecular chain via in-situ polymerization, resulting in a graphene oxide-modified waterborne polyurethane sizing agent. The study investigated the effect of graphene oxide content on the thermal properties and water resistance of the waterborne polyurethane materials, as well as the effect of graphene oxide content on the interlayer shear properties of carbon fiber nylon 6 composites prepared by graphene oxide modified waterborne polyurethane as sizing agent was also studied. Results showed that the thermal stability and water resistance of the waterborne polyurethane material were progressively enhanced with increasing graphene oxide content. Furthermore, at a graphene oxide content of 0.7 %, the interlaminar shear strength of carbon fiber/nylon 6 composites reached 65.0 MPa, which is 92.8 % higher than that of composites using commercial epoxy resin sizing agents. The enhancement mechanism of interlaminar shear strength was further analyzed, providing important theoretical guidance and a feasible strategy for developing high-performance sizing agents.