Interfacial Improvement of Carbon Fiber/Poly (Ether Ether Ketone) Composites by Coating Water‐Based Sulfonated Poly (Ether Ether Ketone) and Carbon Nanotube Composite Sizing Agent

ABSTRACT This study presents the development of a water‐based sulfonated poly (ether ether ketone) (sPEEK)/carboxylated multiwalled carbon nanotubes (MWCNTs‐COOH) composite sizing agent, which is aimed at enhancing the interfacial bonding of carbon fiber/poly (ether ether ketone) (CF/PEEK) composites. The composite sizing agent, consisting of MWCNTs and sPEEK, was designed to improve the interfacial interaction between CF and the PEEK matrix. The incorporation of MWCNTs increased the surface roughness of CF, providing more sites for mechanical interlocking between CF and PEEK, thereby improving the interfacial shear strength (IFSS) to 65.8 MPa. Additionally, the chemical structure of sPEEK is similar to the PEEK matrix, which could enhance the compatibility between fiber and resin through the diffusion and entanglement of sPEEK and PEEK molecular chains, further strengthening the interfacial adhesion. The CF/PEEK composites treated with the sPEEK/CNT composite sizing agent exhibited a maximum IFSS of 81.2 MPa, a 53.8% improvement compared to the desized CF/PEEK composites. These results demonstrate that the sPEEK/CNT composite sizing agent effectively improves the interfacial performance of CF/PEEK composites, providing a promising solution for the preparation of high‐performance CF reinforced thermoplastic composites.