Dispersion state of multi-walled carbon nanotubes in the UHMWPE matrix: Effects on the tribological and mechanical response

Abstract

The distribution state and concentration of multi-walled carbon nanotubes (MWCNTs) are predominant factors in the reinforcement of the ultra-high molecular weight polyethylene (UHMWPE). The dispersion state of large-diameter MWCNT in the UHMWPE matrix loaded with three concentrations of MWCNTs was investigated, along with the mechanical and tribological response of the MWCNT/UHMWPE composites. Re-agglomeration of MWCNTs was evidenced in the polymer matrix, with a significant increase in the composites loaded with 1.0 wt% of MWCNTs, inducing defects and lack of fusion in the polymer. The intensity of these defects increases the propagation of interlaminar cracks and posterior fracture, leading to the release of large particles. The tribological response was enhanced with the MWCNTs content, however, this enhancement was less evident with the degree of defects induced by the MWCNTs agglomeration. Despite the improved wear performance of the composites, hardness did not make a contribution to this improvement.