Avaliação do desempenho tribológico do polietileno de ultra alta massa molar nanoestruturado contendo óxido de grafeno reduzido

Abstract

This work focuses on investigating the tribological performance of ultra-high molecular weight polyethylene (UHMWPE) and a nanocomposite containing reduced graphene oxide (rGO) in low concentration (0.25 wt.%), developed for use as a liner in iron ore transfer chutes. The objective is to correlate the morphological structures of these materials with their mechanical properties and tribological characteristics. Thermal and morphological analyses revealed that the addition of rGO modified the polymer matrix structure, as evidenced by scanning electron microscopy (SEM) images. Differential scanning calorimetry (DSC) results indicated an increase in the crystallinity degree of the nanocomposite compared to the non-reinforced UHMWPE. The nanocomposite showed significant improvements in mechanical behavior, including an 11% increase in impact resistance (Charpy) and a 38% increase in Shore D hardness. Instrumented indentation results showed a 49% increase in hardness and a 13% increase in the elastic modulus of the nanocomposite, indicating higher resistance to plastic deformation and greater stiffness. In tribological tests, the nanocomposite demonstrated significantly superior performance, with a 15% reduction in volumetric loss in the pin-on-disk abrasion test compared to non-reinforced UHMWPE. In the rubber wheel test, the volumetric loss reduction was up to 37%. Additionally, through variance analysis (ANOVA), it was possible to determine the influence of the rubber wheel test parameters on the tribological response of the polymeric materials. Finally, in the sliding abrasion tumbler test, after 51 hours, the volumetric loss was 21% lower for the nanocomposite. Optical microscopy, profilometry, and SEM analyses revealed changes in the surface topography of the nanocomposite after the abrasion tests, highlighting the effectiveness of rGO in improving the tribological performance of UHMWPE.