Enhancement of interfacial performance of carbon fiber reinforced polypropylene composites by dual action of polyetherimide nanoparticles and coatings

In order to enhance the interfacial bonding between carbon fibers (CFs) and polypropylene (PP) resin, a multiscale modification system of composite interfacial physical embedding-chemical bonding was established by the dual action of polyetherimide (PEI) nanoparticles and coatings prepared on the surface of CFs. Hemispherical PEI nanoparticles were prepared by evaporation-induced treatment to improve the mechanical interlocking ability of the composite interface. Based on PEI nanoparticles, coatings with different concentrations were introduced on the CF surface to exert chemical bonds and enhance compatibility with the PP resin. The surface properties of CFs, including chemical composition, morphology, wettability, and interfacial adhesion were systematically investigated. Compared with unmodified CFs, modified CFs showed increased surface roughness, enhanced surface activity, and improved surface wettability. Due to the dual action of PEI nanoparticles and coatings, the tensile strength and interlaminar shear strength (ILSS) of the composite were both enhanced. Specifically, the ILSS of PCF-0.10/PP composite increased by 119.35%, indicating that the dual modification significantly improved the mechanical reinforcement and interfacial adhesion of the composite. On this basis, the interfacial strengthening mechanism in the composite was proposed, and an effective and feasible method was proposed to improve the interfacial performance of composites. The method has the limitation of a long preparation time, but it is simple, easy, and cost-effective, which provides a promising prospect for the application of composites.