Modeling of thermal aging of cable polymer composition based on ethylene vinyl acetate

The aging of a cable polymer shell composition based on ethylene vinyl acetate has been studied. During accelerated aging tests in the temperature range from 110 to 150 °С, the change in the mechanical and thermal properties of the elastomeric samples was monitored. The sample properties were controlled by measuring the following characteristics: the relative elongation at break (REB), the indentation modulus of elasticity (IME), the oxidative induction temperature, and the oxidative induction time. To simulate a REB change during the aging, an empirical kinetic equation was used, which reflects the three stages of elastomer aging: finish cross-linking, inhibited oxidation and non-inhibited oxidation. The developed model was validated, and a forecast of the REB of the shell elastomer for the maximum operating temperature of low-voltage cables’ operation, stipulated by technical documents is presented. The possibility of a non-destructive testing and prediction of the cable state, using IME is demonstrated. A system of models associated with each other with common physical parameters has been developed. It includes both the models describing a change in the mechanical properties in the course of the thermal aging and the thermal-oxidative parameters of the polymer composition based on ethylene vinyl acetate.