So-called "delamination destruction" is often observed on ultra-high molecular polyethylene (UHMWPE) knee components. We reported that the grain boundary becomes the place at which destruction takes place and presence of D,L-α-Tocopherol (vitamin E:VE) at the grain boundary prevents crack propagation. It was also reported that partial hardening (or degradation) might be prevented by the anti-oxidization effect of VE. The purpose of this study is to clarify the mechanism in which VE suppresses the influence of gamma-ray irradiation, and the mechanism of delamination destruction using the image correlation method with tensile-testing. The results showed that the increase-rate of volume strain in the grain boundary was lower than at in grain for the gamma-irradiated UHMWPE. In contrast, the virgin sample and the VE added sample show contrary results.
