Tribological Performance and Contact Stress Analysis of UV-Curable Acrylic/ZnO Nanocomposites

UV-curable acrylic polymers are promising for advanced coating applications; however, they suffer from low mechanical strength and wear resistance. This study investigated the effects of zinc oxide (ZnO) nanoparticle incorporation (0, 1, 3, and 5 wt.%) on mechanical, surface, and tribological properties of UV-curable acrylic polymer nanocomposites. The elastic modulus increased from 9.41 MPa (bare polymer) to 22.39 MPa (5 wt.% ZnO), a 138% improvement. X-ray diffraction (XRD) analysis confirmed the formation of a crystalline region at the polymer-ZnO interface, with crystallite sizes reaching 121.94 nm compared to 7.95 nm for the bare-polymer. Surface roughness increased (0.99 to 2.45 μm), while contact angle decreased (66° to 49.23°), indicating improved wettability. Under high-load conditions (100 mN, 2 Hz), the 5 wt.% ZnO composite exhibited the lowest friction coefficient (0.29) and the second-lowest wear rate (6 × 10⁻⁷ mm³/N·mm), representing 26% and 63% reductions compared to bare polymer, respectively. Finite element analysis (FEA) revealed that an increased elastic modulus reduced the indentation depth and increased the localized contact stress, contributing to improved wear resistance of the coating. This study demonstrates the structure-property-performance relationships for designing durable acrylic polymer-based nanocomposite coating.