Modeling of Thermal Aging of a Cable Polymer Composition Based on Ethylene Vinyl Acetate

Aging of a cable polymer sheath’s composition based on ethylene vinyl acetate was studied. During accelerated tests in the temperature range from 110 to 150°C, changes in the mechanical and thermal properties of elastomer samples were monitored. Condition of samples was monitored by measuring elongation at break (EB), elastic modulus at indentation (EMI), oxidative induction temperature, and oxidative induction period. An empirical kinetic equation reflecting three stages of elastomer aging—cross linking, inhibited oxidation, and uninhibited oxidation—was used to model elongation at break during aging. Confirmation of the developed model was obtained, and a forecast of the shell elastomer tensile strain at break was presented for the maximum operating temperature of low-voltage cables specified in the technical documents. The possibility of nondestructive testing and prediction of the condition of these cables by the EMI value is shown. A system of models related by general physical parameters has been developed, which includes both models describing the change in mechanical properties during thermal aging and thermo-oxidative parameters of a polymer composition based on ethylene vinyl acetate.