As a result, polymers are ubiquitous in applications ranging from prosthetic implants in the human body, high speed bearings and seals in gas turbine engines, to bearings in electrically powered drivetrains. A characteristic feature of polymeric materials which enables such diverse use is the tunability of their functional properties – mechanical, thermal, electrical and tribological – to meet diverse, often harsh operating conditions in these environments.
Predictive design of tribological polymer composites, in the context of multifunctional environments requires a fundamental understanding of mechanisms which drive performance. Empirical evidence suggests that interfacial films play a crucial role in wear resistance of polymer composites. Ultra-low wear systems exhibit the appearance of mechanochemically modified interfacial films, formed in-situ; these are often considered a “predictor” of ultra-low wear. Interfacial films form both on the polymer surface (tribofilms), as well as the sliding counterpart (transfer films) through material transfer and consolidation. Spectroscopic analyses reveal that interfacial films are chemically modified relative to the unworn composite, presumably through strain-mediated pathways. Filler-matrix interactions invariably affect the formation of these films by regulating primary wear of the composite, however the mechanisms by which these interactions operate remain unknown. It is therefore evident that “good” transfer films accompany ultra-low wear systems, however design rules that promote such films, for example through the choice of suitable fillers in the polymer matrix remain all but non-existent. The goal of this research is to enable the development of predictive design rules for ultra-low wear tribological polymer composites.
