Improved Mechanical Properties of Carbon Fiber Reinforced Polyetheretherketone Composites via Polyethersulfone Sizing Agent

ABSTRACT This study employed polyethersulfone (PES) as a sizing agent for carbon fiber (CF) to enhance the interfacial bonding performance between CF and polyetheretherketone (PEEK). The effects of PES sizing on the thermal stability, surface characteristics, and composite properties were systematically investigated using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), contact angle measurements, and mechanical property tests. The results demonstrated that PES sizing significantly improved the thermal stability of CFs, with a mass loss of less than 0.2% at 450°C. After heat treatment at 380°C, the tensile strength of PES‐sized CF reached 2034.7 MPa, representing a 95.7% increase compared to commercial CF. The surface free energy of PES‐sized CF increased from 18.32 to 47.86 mJ/m 2 , accompanied by enhanced surface polarity, wettability, and interfacial adhesion with the PEEK matrix. Consequently, compared with ECF/PEEK composites, the tensile strength, flexural strength, and impact strength of PESCF/PEEK composites have increased by 20.11%, 24.47%, and 39.17%, respectively.