Study on Acceleration Factor for Degradation of Safety Cable Insulations under Heat-Radiation Simultaneous Stress Application

Abstract

Flame-retardant ethylene-propylene-diene rubbers were subjected to acceleration aging with simultaneous heat and radiation in the air to evaluate the acceleration factor. Mechanical properties under various dose rates, temperatures, and degradation time (0-1050 Gy/h, 80-120°C, 0-42481 hours) were measured to find the optimal shift factor to minimize the data scattering. The estimated shift factor was applied to the oxygen induction time which may correspond to remaining amount of antioxidants. Obtained aging characteristics were found to suggest that the degradation proceeds after consumption of antioxidants. The present study also revealed that the optimum shift parameter of the degradation process may also be applied to aging characteristics obtained under low oxygen pressure conditions.