Influence of ZnO nanoparticle filler on the properties and wear resistance of polycarbonate

Polycarbonate (PC)/zinc oxide (ZnO) nanocomposites containing 0.1, 0.5, 1 or 5 wt.% nanoparticles have been prepared by milling and injection molding and characterized by DSC, TGA, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Increasing the concentration of ZnO nanoparticles reduces the glass transition temperature and the degradation temperature of the nanocomposites with respect to neat PC. The nanocomposites containing 0.5 and 1 wt.%ZnO were selected for mechanical and tribological studies. PC + 0.5%ZnO presents a higher modulus and similar tensile strength compared to neat PC, with a 74% reduction in the elongation at break. A ZnO concentration of 1 wt.% dramatically reduces both the tensile strength and the elongation at break of PC. A 0.5 wt.% proportion of ZnO nanoparticles increases hardness and reduces the wear rate with respect to neat PC both under pin-on-disk and under thrust-washer contact conditions. Wear mechanisms are discussed.