UNDERSTANDING OPTICAL-EMISSIONS FROM ELECTRICALLY STRESSED INSULATINGPOLYMERS - ELECTROLUMINESCENCE IN POLY(ETHYLENE-TEREPHTHALATE) AND POLY(ETHYLENE 2,6-NAPHTHALATE) FILMS

Wear-out and breakdown of polymers used as insulating materials are cl osely related to the dissipation of electrostatic energy in space char ge regions. A fraction of this energy is radiated off by electrolumine scence which can be considered as a pre-breakdown warning and provides a probe to investigate the mechanisms leading to structural degradati on. Electroluminescence emission from two aromatic polyesters is studi ed-poly(ethylene terephthalate) and poly(ethylene 2,6-naphthalate). We investigate the excitation processes of the luminescent centres, the nature of the centres, and the relationship of the emission features t o electrical ageing. Sample electroluminescence is excited by de and a c voltages under a uniform field configuration. The discussion relies on the analysis of the charge transport process in the luminescent reg ime, the acquisition of electroluminescence and photoluminescence spec tra, and the investigation of the field effect on photoluminescence.