Photoluminescence, recombination induced luminescence and electroluminescence in epoxy resin

The dielectric breakdown of epoxies is preceded by light emission, or so-called electroluminescence, from the solid state material. Very little is known about the luminescence properties of epoxies. The aim of this paper is to derive information that can be used as a basis with which to understand the nature of the excited states and their involvement in the electrical degradation processes. Three different kinds of stimulation were used to excite the material luminescence. Photoluminescence was performed on the base resin, the hardener and the cured resin. Luminescence excited by a silent discharge has been analysed to identify which of the luminescent centres are optically active upon the recombination of electrical charges and could therefore act as charge traps. Finally, the electroluminescence spectrum has been acquired and compared with the previous ones. Although the identification of the origin of these emissions is far from being complete, it has been found that the photoluminescence from the cured resin is due to in-chain chromophores, which act as trapping centres. The excited states involved in photoluminescence also seem to be involved in electroluminescence, but other components are detected as well, which could be due to the degradation of the resin molecule under the effect of the electric stress.