Synthesis and characterization studies of high-density polyethylene -based nanocomposites with enhanced surface energy, tribological, and electrical properties

High-density polyethylene (HDPE) and different weight fractions of multi-wall carbon nanotubes (MWCNTs) in the weight fraction of 1, 2, 3, and 5% were successful fabricated using magnetic stirring-twin screw extrusion and subjected to wear tests at two load variations maintaining a fixed speed. Three wt. % MWCNTs/HDPE nanocomposites exhibited the best tribological performance, so this composition was selected to develop hybrid nanocomposites with the addition of 0.6, 1.2, 1.8, 2.4, and 3 wt % Nano-alumina particles. Three wt. % MWCNTs+1.2 wt % Al2O3/HDPE nanocomposites outperformed other compositions and exhibited leading tribological performance and the lowest friction coefficient attributed to creating stable, coherent, and adherent transfer film. MWCNTs and Al2O3 reinforcement mutated the wettability (from contact angle of ~93° ± 2°–~116.6° ± 3°) and surface energy (from ~25 to ~17.6 mN/m) of nanocomposites compared to pure HDPE. Investigations on electrical properties revealed that the conductivity remained unaffected up to 2 wt % of MWCNTs. Three wt. % MWCNTs/HDPE nanocomposites marked a sharp increase in the conductivity up to a frequency of 4.75 × 106 Hz, after which it decreased and followed the same trend as pure HDPE, and 1, 2 wt % nanocomposites. The permittivity of the nanocomposites increased with the increment in wt. % of MWCNTs at low frequency, and beyond a critical frequency, it became frequency independent. The percolation threshold of MWCNTs/HDPE nanocomposites appeared between 2 and 3 wt %.