Effective role of d-sorbitol in enhancing the oxidation stability and crosslink density of tea polyphenol-stabilized ultra-high molecular weight polyethylene

Ultra-high molecular weight polyethylene (UHMWPE) is a versatile polymer with various industrial applications, particularly in orthopedic implants and structural materials. However, its susceptibility to oxidation limits its utility in demanding environments. This study investigates the potential of d-sorbitol (DS), a natural polyol, in enhancing the oxidation stability and crosslink density of UHMWPE when stabilized with tea polyphenols. Tea polyphenols, such as epigallocatechin gallate (EGCG), have been previously evaluated as a promising candidate to stabilize UHMWPE against oxidation without affecting its crosslink density. However, the higher content of EGCG has adverse effect on its mechanical properties. It is hypothesized that addition of DS to EGCG can improve the oxidation and crosslink density of UHMWPE blends. For this purpose, EGCG/DS was blended with UHMWPE at low antioxidant concentrations (≤ 1 wt%), and its comprehensive performance was evaluated. Results demonstrate that the incorporation of d-sorbitol effectively retards oxidation-induced degradation in tea polyphenol-stabilized UHMWPE. The presence of d-sorbitol enhances the crosslink density within the polymer matrix, thereby improving its resistance to oxidative stress. Furthermore, the study elucidates the underlying mechanisms through which DS interacts with EGCG and UHMWPE, elucidating the formation of stable complexes that mitigate oxidative damage. The in vitro biocompatibility of the blends was also very promising for use in artificial joints.