A Multi-dimensional Model to Describe the Ageing Process in Polymers Used for Electrical Insulation

A lot of knowledge on the behaviour of polymers used as electrical insulators has been acquired over the last decades. The major difference in life models describing the electrical ageing process in these materials is based on the cause initiating the degradation. The role of space charges as a primary step or consequence of ageing became contradictory factors. However, most of these models rely on a thermodynamical approach. The ageing process is assumed to be dominated by a single reaction that involves the initial state and the final state. A "double well potential" representation is systematically provided by the authors to describe the free energy variation and the moiety transfer in the system during the ageing process. In our bibliographical study, we have not yet found an entirely reliable model which takes into consideration the distribution of the functions in the molecular mobility of polymer chains. It is well known that polymers present a so called energy distribution function. The main interest of this analysis is the possibility to integrate the distribution function concept associated with the barrier energies in electrical insulators life models.