Tribological and mechanical performance of UHMWPE-based hybrid composites reinforced with Hap and GNPs

Abstract Ultra-high-molecular-weight polyethylene (UHMWPE) is widely used in orthopedic implants due to its excellent wear resistance and biocompatibility; however, its use is limited by the generation of wear debris, which can lead to osteolysis and implant failure. This study aims to develop and characterize UHMWPE-based nanocomposites reinforced with graphene nanoplatelets (GNPs) and hydroxyapatite (HAp) to enhance mechanical performance, wear resistance, and bioactivity. UHMWPE powders were reinforced with 0.5–1.0 wt% GNPs and 10 wt% HAp, followed by homogeneous mixing via planetary ball milling, compaction under 6–10 tons of load, and sintering at 270 °C for 5–10 minutes. The composites were analyzed using metallographic observation, Shore D hardness testing, SEM-EDS characterization, and pin-on-disk wear testing. The results showed that the UHMWPE-10% HAp-0.5% GNP composite, compacted at 6 tons and sintered for 10 minutes, exhibited the highest hardness value of 45.40 HD and the lowest wear loss of 0.074 grams. SEM-EDS analysis confirmed the dominant presence of carbon, phosphorus, and calcium, indicating successful integration of the reinforcements. This study demonstrates that the synergistic addition of GNPs and HAp significantly improves the mechanical and tribological properties of UHMWPE composites, offering promising potential for advanced biomedical applications.