Effect of O ₂ ‐Ar Mixed Gas Plasma Treatment on the Surface Properties of Carbon Fibers and the Interfacial Properties of Composites

ABSTRACT To improve the interfacial bonding strength between T800 carbon fibers (CF) and polyimide resin, this study employed O ₂ ‐Ar mixed gas plasma for modification treatment of the CF. In this study, the gas flow rates were controlled to indirectly regulate the gas ratio, and O ₂ ‐Ar mixed‐gas component experiments were conducted. The optimal O ₂ ‐Ar mixing ratio was determined to be 5:5. Based on this optimal ratio, orthogonal experiments were carried out to determine the optimal treatment conditions under O ₂ ‐Ar mixed‐gas plasma. Under optimal treatment conditions, both the room‐temperature and high‐temperature interlaminar shear strength (ILSS) of the composites were significantly improved. The room‐temperature ILSS increased from 100.89 to 124.75 MPa, corresponding to an enhancement of 23.6%; while the ILSS at 300°C increased from 69.98 to 97.42 MPa, representing an improvement of 39.2%. By combining objective evidence from microscopic characterization, carbon fiber contact angle and surface energy data, mechanical property data, and the cross‐section of the composite after failure, the synergistic mechanism of the O ₂ ‐Ar mixed gas was elucidated, providing ideas and methods that can serve as a reference for subsequent research on multi‐component mixed gases.