Comparative study of tribological behaviors of compression molded polyimide under varying load conditions

Tribological evaluation of neat polyimide is essential for understanding its intrinsic behavior under extreme conditions and providing guidance to optimize high-performance composites. In this study, neat polyimide samples were prepared via compression molding, and their tribological behaviors were evaluated using a reciprocating tribo-meter under dry conditions in point contact. The results revealed a load-dependent transition in wear mechanisms: fatigue wear with cracks perpendicular to the sliding direction at lower loads evolved into delamination at higher loads. At the highest load, unstable friction behavior was accompanied by severe surface damage, which was consistent with enhanced material transfer evidenced by increased transfer film formation on the counterpart surfaces. Furthermore, carbonized polyimide on the counterpart surfaces was observed, along with evidence of chelation between the transferred polyimide and the metal. These findings deepen the understanding of the tribological characteristics of neat polyimide and provide fundamental insights for enhancing the tribological performance of polyimide composites through modification with additives or fillers.