Nanometer Al₂O₃ Reinforced Polyetheretherketone (PEEK) Composites And Their Properties

In this paper the process, physical and mechanical properties and tribological behaviour of PEEK composites filled with nanometer Al2O3, nanometer SiO2 and polytetrafluoroethylene (PTFE) by means of various dispersing techniques were studied.Twenty composites were prepared with PEEK matrix modified by various reinforcements and processing techniques, including the size and content of nano particles, surface treating agent, the content of PTFE and different dispersing methods such as directly mechanical dispersing, mechanical dispersing in liquid, ultrasonically dispersing in liquid and vibrationally dispersing in liquid. The PEEK matrixes provided by different companies are also included in the tests. Atomic Force Microscope (AFM) analysis shows that the processing techniques mentioned above could obtain a nanoscale dispersion of the filled particles in the polymer matrix.It is revealed by the property determination that the glass transition temperature (Tg) is increased and enthalpy (AHf) is decreased as the nanosized Al2O3 is added to the PEEK. The higher strengths in tension, compression, bending and impact are also achieved in the nano Al2O3 contained polymer in comparison with the unfilled PEEK. The composite with 5% (wt) Al2O3 of 15nm particle size has higher tension strength and impact strength than that with 10% (wt) Al2O3 of 15nm particle size or that with 5% (wt) Al2O3 of 100nm particle size. The nanosized Al2O3 plays a more important role in modifying the mechanical properties of the materials than SiO2 does. When the Al2O3 particles are treated with surfactant, a further improvement in impact strength of the composite isobtained. It is more efficient to increase the mechanical properties of the composite by means of mechanical dispersing in liquid in comparison with directly mechanical dispersing. As regards the composites containing PTFE, the mechanical properties is decreasing obviously as the increasing of the nano Al2O3 particle size.Under the laboratory air condition, the sliding and fretting wear resistance were considerably improved in the nanometer Al2O3 particle filled PEEK composites, especially the PEEK composite containing 5% (wt) Al2O3 with 15nm particle size. A thin, smooth and tenacious polymeric transferred film was found on the steel surface when it was paired with some certain composites, for instance, containing 5% (wt) Al2O3 with 15nm particle size. It is also found that the lower fretting wear rate the composite indicates, the smaller wear scar is on the counterpart steel surface. Adding PTFE could effect the tribological behaviour of the reinforced composites by degrading the wear resistance and improving the frictional properties.This research project is of significance for exploring new ways in the development of polymer matrix based composite materials which are more and more important for the structured components due to their light weight, high strength, high stiffness and excellent tribological properties.