Effect of Surface Modification on Long-Term Mechanical and Tribological Performance of Biomedical Polymers

Abstract Long-term mechanical durability of biomedical polymers is essential for their effectiveness in hip and knee joint replacement prostheses, where materials experience various stress situations in the presence of physiological fluids. However, prolonged exposure to physiological fluids can accelerate moisture absorption, leading to mechanical degradation of the polymers. This can significantly reduce the lifespan of polymers used in various biomedical applications, such as total joint replacement prostheses applications. Surface modification can improve hydrophobicity, which can delay moisture absorption and enhance the resistance to mechanical degradation. Among the various surface modification techniques, surface texturing has drawn significant attention as it does not alter the chemical properties of the material. This study investigates the role of surface texturing in improving the long-term mechanical and tribological performance of Ultrahigh Molecular Weight Polyethylene (UHMWPE) and High-Density Polyethylene (HDPE). UHMWPE and HDPE samples with square, cylindrical, and hemispherical micro-protrusions and micro-cavities were submerged in deionized (DI) water and compared against the mechanical properties of flat samples. Scratch and wear testing was done on flat and textured polymer samples under dry and boundary lubrication scenarios to investigate the effect of surface modification on tribological behavior of polymers. Relationships between long-term mechanical behavior and tribological performance under dry and boundary lubrication scenarios were sought. The findings highlight the crucial role of surface texturing in preserving mechanical and tribological performance under physiological conditions.