Effect of Ionizing Radiation on the Crystalline Morphology of Ultra High Molecular Weight Polyethylene (UHMWPE)

The two main applications of ionizing radiation and Ultra High Molecular Weight Polyethylene (UHMWPE) are in space radiation shielding and articulating orthopedic implants (hips and knees). Samples are exposed to both proton and gamma irradiation. Proton irradiation doses are varied from 0-8.7 kGy. Proton Irradiation showed significant increases in crosslinking on the surface, which interferes with recrystallization of the polymer. Gamma Irradiation is conducted at a high (2.9 kGy/hr) and low (0.25 kGy/hr) dose rate at integral doses of 75 and 150 kGy. Gamma irradiation shows significant crosslinking and recrystallization in the center of the sample where oxygen diffusion is limited.