Water-based PES-NaPSS sizing agent without surfactant for interface enhancement of CF/PEEK composites

Improving the weak interfacial bonding of carbon fiber (CF)/polyetheretherketone (PEEK) composites is an extremely urgent need. Addressing this issue, sizing modification on CF surfaces is a conventional and effective method. In this work, polyethersulfone-polystyrene sulfonate sodium (PES-NaPSS) was successfully synthesized by UV illumination. A novel surfactant-free aqueous PES-NaPSS sizing agent was prepared by emulsion/solvent evaporation method to regulate the interface of CF/PEEK composites. From the XPS and SEM results, it can be seen that PES-NaPSS was uniformly coated on the CF surfaces, which introduced the reactive groups on the CF surfaces. The PES-NaPSS sizing agent exhibits good thermal performance and storage stability, meeting the needs for high temperature processing of CF/PEEK composites. Compared with the unsized CF/PEEK composites, the ILSS, flexural strength and modulus of the 0.9 wt% PES-NaPSS modified CF/PEEK composite are improved by 32.8 %, 40.3 % and 37.4 %, respectively. Accordingly, the mechanisms of the interface improvement are physical riveting, chain entanglement, chemical and physical interactions between the PES-NaPSS and PEEK matrix. This green and effective method of interface improvement will supply a prerequisite for the extensive application of CF/PEEK composites.