# Multiscale Synergistic Investigation on the Mechanical and Tribological Performances of Graphene-Reinforced PEEK/PTFE Composites

## TL;DR

Graphene-reinforced PEEK/PTFE composites improve mechanical strength and wear resistance without reducing lubricity.

## Contribution

The study introduces graphene nanosheets to resolve the trade-off between wear resistance and lubricity in PEEK/PTFE composites.

## Key findings

- 2 wt% graphene improved tensile strength by 10.58% and reduced wear rate by 17.88%.
- Graphene formed a dense network that enhanced load transfer and suppressed delamination.
- MD simulations showed reduced free volume and mitigation of chain scission during friction.

## Abstract

Polytetrafluoroethylene (PTFE) is a self-lubricating material but has poor wear resistance. The wear resistance of the composites was enhanced by the incorporation of polyetheretherketone (PEEK), whereas the friction-reducing performance was compromised, thus resulting in an inherent trade-off between wear resistance and lubricity. Graphene nanosheets (GNSs) with high strength and lubricity were introduced as a reinforcement for PEEK/PTFE composites. Composite specimens with varying GNS contents were fabricated and characterized for their mechanical and tribological properties and wear morphologies. Combined with molecular dynamics (MD) simulations, the micro-mechanisms were further elucidated. The optimal GNS content was determined to be 2 wt%, which improved the tensile strength by 10.58% and reduced the wear rate by 17.88% compared to PEEK/PTFE. It achieved the synchronous enhancement of mechanical strength and wear resistance while maintaining desirable friction-reducing performance. MD simulation results demonstrated that the strong interfacial interactions between GNSx and the polymer enabled GNSs to adsorb polymer chains and form a dense rigid network with reduced free volume (FV). The mechanical properties were enhanced by efficient load transfer and the suppression of interfacial delamination enabled by this unique structure; meanwhile, wear resistance was improved due to the mitigation of friction-induced molecular chain scission.