Influence of mixing process on the mechanical and tribological properties of PTFE composites

Abstract

Polytetrafluoroethylene (PTFE) composites filled with glass fibre (GF) and graphite were prepared by internal mixer and moulded using compression mould to produce test samples. A high-speed mixer was selected to simulate uneven mixing and excessive mixing conditions by controlling different mixing time. The work studied the mixing process's influence on the mechanical and tribological properties of PTFE composites and investigated the state of glass fibres on the unworn/ worn composite surface with SEM characterisation. The results revealed that the mechanical and tribological properties of composites were associated with the mixing process. For the non-uniform mixing of composite materials, glass-fibre particles fell off the matrix earlier, hindering glass fibre particles in bearing the matrix load. Moreover, excessive mixing increased mixing temperature, the matrix material softened due to overheating, which caused the adhesive wear between the steel ring and PTFE composites. It increased the volume wear rate of composite materials.