Investigation of thermo-mechanical and tribological performance of zirconia-coated MWCNTs reinforced HDPE composites

High-Density Polyethylene (HDPE) composites reinforced with zirconia (ZrO₂)-coated multi-walled carbon nanotubes (MWCNTs) were developed and characterized to enhance their thermal, mechanical, and tribological properties. The functionalization of MWCNTs with ZrO₂ via a hydrothermal method improved dispersion and interfacial bonding within the HDPE matrix. The composites were fabricated using melt blending followed by injection molding with varying ZrO₂-MWCNT loadings (1–4 wt%). Density, thermal stability, crystallinity, dynamic mechanical properties, and tribological performance were evaluated. The results revealed a significant enhancement in both tensile and flexural strengths of the composite, with the maximum improvement observed at 3 wt% ZrO₂-MWCNT reinforcement—showing approximately 50 % increase in tensile strength and 32 % increase in flexural strength compared to the neat HDPE. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed enhanced thermal stability and crystallinity. Dynamic mechanical analysis (DMA) demonstrated increased storage modulus and reduced damping factor, indicating improved stiffness. Furthermore, tribological tests revealed a decrease in wear rate and coefficient of friction at optimal filler concentrations. These findings suggest that ZrO₂-coated MWCNTs are effective reinforcements for HDPE, making these composites promising candidates for hot water transportation pipes in reactors, highly resistant corrosion and is frequently used as an insulator in high-temperature applications.