Multiscale modelling of permittivity of polymers with aging: analysis of molecular scale properties and their impact on electrical permittivity

This work presents an innovative model for the derivation of permittivity evolution of polyethylene (PE)-based materials with aging. First, the derivation of the microscale contributions to the real permittivity of methylene unit [constitutive repetitive unit (CRU) of PE] and its oxidation products, that is, ketones and hydroperoxides, in the solid state is presented. Then, a chemical kinetic model is recalled predicting the concentration, under proper hypotheses, of the oxidized species created during polymer aging. The proposed model combines the concentrations of methylene unit and its oxidation products with the respective contribution to permittivity, providing the trend of permittivity of polymer with aging. Results depict good agreement with the experimental data, validating the model.