Fig. 1. Experimental process for accelerated aging process of UHMWPE

Fig. 2. Typical spectra of several free radicals^[30-31]; ×3/5/6 means magnifying by 3/5/6 times

Fig. 3. Evolution of radiation-induced UHMWPE radicals in air at 25 °C over time: (a) radical concentration as a function of time; (b) EPR curves of the sample in air; (c) EPR curves of the sample in nitrogen; ×5/10 means magnifying by 5/10 times

Fig. 4. Changes in free radical concentration, EPR spectra of samples A28 and N28 during accelerated aging process:(a) radical concentration as a function of time; (b) EPR curves for A28; (c) EPR curves for N28; ×5/50 means magnifying by 5/50 times

Fig. 5. Changes in free radical concentration and EPR spectra of UHMWPE with absorbed dose of 50 kGy during accelerated aging after storage in air for a certain time

Fig. 6. Evolution of 6 A0/N0, N28, A28 in nitrogen atmosphere at 70 °C