Sara Atwood

Second year PhD student
 Mechanical Engineering
University of California, Berkeley

My research investigates the various microstructures produced by state-of-the-art clinically-relevant sterilization and cross-linking procedures, as well as some experimental processes. Ultra High Molecular Weight Polyethylene (UHMWPE) is a polymer commonly used as the bearing material between two metal components in total joint replacements. UHMWPE is approximately 50% amorphous phase and 50% crystalline phase, with the crystalline phase forming plate-like structures called lamellae. Current processing treatments for UHMWPE for joint replacement involve the use of gamma radiation to cross-link the long polymer chains in an effort to improve wear performance. However, it has been shown that cross-linking also has a negative effect on fracture and fatigue behavior. The goal of this research is to understand how microstructure relates to fatigue and wear performance, and how processing affects microstructure, so that ultimately the UHMWPE can be optimized for use in total joint replacements.

 

SEM images of conventional untreated GUR 1050 UHMWPE with the plate-like lamellae clearly visible.