Aging Mechanism Analysis of Argon Plasma Treatment on Aramid Fiber III /Epoxy Composites Interfacial Properties

ABSTRACT This study employs argon plasma treatment on Aramid fiber III and investigates the changes in various properties under different aging times. Surface analysis techniques including x‐ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy, combined with interfacial shear strength and dynamic contact angle measurements, were employed to systematically characterize the chemical composition, microstructure, roughness, wettability, and interfacial bond strength of the fiber surface. The fracture morphology at the interface before and after fiber pull‐out was also analyzed. Results indicate: After 3 days of aging, the (O + N)/C ratio increased by 2.28%, and interfacial shear strength reached 42.34 MPa, an increase of 8.90%. After 7 and 30 days, the (O + N)/C ratio decreased by 11.72% and 6.78%, respectively, while interfacial strength remained stable with no significant fluctuations. Surface energy and roughness showed minimal change throughout aging, with only a 2.1% decrease after 30 days, indicating well‐preserved interfacial bonding. Molecular dynamics simulations reveal that the quantity, position, and orientation of active functional groups modulate the interfacial bonding energy, clarifying the mechanism by which aging duration influences interface performance.