IMPACT OF SURFACE TEXTURE ON MOISTURE ABSORPTION AND LONG-TERM MECHANICAL PERFORMANCE OF BIOMEDICAL POLYMERS.

Mechanical integrity over time is a crucial factor for various biomedical polymers used in numerous applications, including total joint replacement prostheses applications. However, moisture absorption can significantly affect the long-term mechanical behavior of these polymers, leading to potential degradation and failure. This research investigates how surface texture influences the long-term mechanical behavior of two biomedical polymers, High Density Polyethylene (HDPE) and Ultrahigh Molecular Weight Polyethylene (UHMWPE). A comprehensive analysis is conducted by comparing the mechanical performance of flat/smooth and textured HDPE and UHMWPE specimens subjected to moisture exposure over an extended period. A combination of laser engraving and hot-pressing techniques is used to introduce textures, with variation in geometry and dimension, on the surfaces of model polymers. Tensile tests are performed on both flat/smooth and textured specimens stored under dry condition and in moisture environment for up to 90 days. Effects of moisture absorption on mechanical properties are studied and compared for the flat/smooth samples as well as among different textured samples with varying geometries and dimensions. The results demonstrate that the introduction of surface texture delays moisture absorption compared to flat/smooth samples. This delayed moisture absorption enhances the long-term mechanical durability of polymers under moisture environment. Dynamic mechanical analysis (DMA) is conducted to understand the molecular mechanisms responsible for the observed long-term mechanical behavior. The findings highlight the critical role surface texture plays in mitigating moisture-induced degradation, thereby enhancing the long-term mechanical performance of biomedical polymers in moisture environments.