Tribological response of UHMWPE lubricated with nanomaterials blended jatropha oil

Growing demands for environmental sustainability and biodegradability have intensified research on bio-based lubricants extracted from renewable resources using nano-additives to enhance its tribological performance. Thus, this study investigates the tribological responses of ultra-high-molecular-weight polyethylene (UHMWPE) lubricated with jatropha oil blended with graphite, graphene, and molybdenum disulfide (MoS 2 ) nanoparticles. These nanoparticles were blended in jatropha oil having concentrations of 0.25, 0.5 and 1 wt.%. The addition of nanoparticles increased both viscosity and thermal conductivity of the blended oil. Tribological tests were conducted at different PV values using a pin-on-disc configuration in accordance with ASTM G99-05 standard. Significant reductions in the coefficient of friction (COF) and specific wear rate (SWR) of UHMWPE have been found with nanoparticles blended oils. MoS 2 exhibited the lowest COF, achieving approximately 35% reduction, while graphite yielded the lowest SWR with approximately 52% reduction for 1 wt.% concentration. Increase in the sliding speed further reduced the COF and SWR due to better lubricating film formation at the interfaces.