The mechanism of degradation of polyethylene in high electrical fields-the mechanism of electric degradation luminescence

It is perhaps common knowledge that electric degradation luminescence precedes breakdown brought about by the voltage application of polyethylene. It is also proposed that this luminescence inception stress is the threshold stress at which polyethylene starts to degrade. However the mechanism of electric degradation luminescence is not clear. In order to clarify this mechanism, a comparative spectra analysis was made of electric degradation luminescence and thermal oxidation luminescence, or void discharge. From the measurement of these luminescence spectra, it is considered that the spectrum of electric degradation luminescence differs from that of thermal oxidation luminescence or void discharge. Electric degradation luminescence is predominantly not from chemical luminescence resulting from the oxidation of polyethylene or partial discharge inside a micro-cavity of polyethylene, but electroluminescence resulting from the re-combination of electron and hole injected into polyethylene