Mechanical properties of ultra-high molecular weight polyethylene irradiated with gamma rays

With the goal of enhancing the creep resistance of ultra-high molecular weight polyethylene (UHMWPE). we performed gamma irradiation and post-irradiation annealing at a low temperature, and investigated the crystalline structures and mechanical properties of the samples. Electron spin resonance spectra reveal that most of the residual radicals are stabilized by annealing at 100 degreesC for 72 h under vacuum. Both the melting temperature and crystallinity increase after increasing the dose and by post-in-addition annealing. When irradiated with the same dose, the quenched sample having a higher amorphous fraction exhibits a lower swell ratio than does the slow-cooled sample. The measured tensile properties correlate well to the crystalline structure of the irradiated and annealed samples. For enhancing creep resistance, high crystallinity appears to be more critical than a high degree of crosslinking.