A Study on the Mechanism of Enhanced Friction Behavior in Functionalized CNT‐Reinforced PEEK/PTFE Composites

ABSTRACT To investigate the effect of functionalized carbon nanotubes (CNTs) on the friction behavior of polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) composites, this study employed friction and wear tests along with molecular dynamics (MD) simulations to comparatively analyze the tribological properties of PEEK/PTFE composites reinforced with different types of functionalized CNT. The results indicated that OH–CNT (hydroxyl), COOH–CNT (carboxyl), and NH 2 –CNT (amino) are all able to enhance the wear resistance of PEEK/PTFE composites compared to unfunctionalized CNT. Specifically, OH–CNT/PEEK/PTFE exhibited superior friction performance, characterized by the lowest friction coefficient and wear rate. Additionally, SEM and EDS analyses of the worn surfaces and counterface surfaces revealed that unmodified CNT tend to form the aggregation phenomenon, which led to localized mechanical performance degradation on the specimen surfaces. Furthermore, the three functionalized CNT significantly improved the surface morphology, resulting in smoother specimen surfaces and a more extensive transfer film coverage on the frictional interface. MD simulations revealed that functionalized CNT induce the adsorption of a substantial number of polymer chains onto their surfaces with combined nonbonded interactions and mechanical interlocking effects. This adsorption mechanism resulted in reduced polymer chain mobility and weakened interactions between polymer chains and counterfaces, thereby significantly enhancing the tribological performance of PTFE composites.