Dynamic mechanical behavior of CaCO3 whisker and polytetrafluoroethylene filled polyetheretherketone composites

The composite blocks of polyetheretherketone(PEEK) filled with different content of calcium carbonate (CaCO3) whisker and polytetrafluoroethylene(PTFE) were prepared by compression molding. Dynamic mechanical thermal analysis(DMTA) was performed on PEEK composites in order to investigate thermally activated molecular relaxation processes and their impact on mechanical properties. Dynamic modulus and mechanical loss factor (tanδ) were continuously measured during a DMTA thermo-scan carried out at 25~300°C. The selected test configuration and operating mode were single cantilever stretching and constant-amplitude forced flexuraloscillation, respectisely. The analysis results show that all materials show a large change in storage modulus at the glass transition temperature(Tg). CaCO3 whisker exhibits an significant effect on dynamic stiffness of the composites at low and high temperatures. The increase of whisker content contributes to a rise of the storage modulus. These modulus of CaCO3 whisker filled PEEK composites are higher than those observed for pure PEEK, especially below Tg. Addition of PTFE, which is closely related to tribological behavior, reduces the storage modulus of CaCO3/PEEK at temperature below Tg, while the storage modulus above Tg do not change much. These effects in thermal mechanical properties are of benefit to improve tribological behavior of the filled PEEK self-lubricating composites.