The Adaptive Tribological Investigation of Polycaprolactam/Graphene Nanocomposites

The design and mechanism of adaptive materials in the field of tribology are of particular importance because of the tribological properties greatly depending on the operating conditions and external environment. Polycaprolactam (PCL) adaptive nanocomposites containing porous graphene impregnated with solid paraffin were prepared by in situ polymerization. The tribological results showed that the designed nanocomposites, which displayed adaptive tribological behaviors, had low and stable friction coefficients and the wear rates compared to neat PCL even under high pressure and velocity condition. The proposed adaptive tribological mechanisms are due to the high load-carrying capabilities of graphene nanosheets forming proper surface texture, the lubricating role of molten paraffin produced at sliding interface under friction heating and the mitigated thermal damage caused by lower surface temperature through depleting friction heat. The as-prepared polycaprolactam composites are expected to broaden the application of such polymers in engineering parts, and the design concept can easily apply to other self-adaptive tribological composites.