Lifetime of polymers in AC electric field

An explanation of the difference in the electric strengths of polymers in AC and DC electric fields has been suggested. Energy release due to the recombination of electrons and holes injected into a polymer dielectric is considered as a factor enhancing electrical aging of these dielectrics in AC electric field. It has been shown that nonradiative relaxation of excited electron states causes bond breaking in macromolecules with the formation of free radicals. Since the ionization energy of free radicals is lower than that of parent molecules, the charge accumulation rate in a polymer dielectric grows. As a result, its lifetime in AC electric field is shorter than in DC field.