The thermal oxidative degradation of an ethylene–tetrafluoroethylene‐copolymer‐based electrical wire insulation

Abstract

Abstract A multidisciplinary spectroscopic evaluation of a commercial wire insulation based on a cross‐linked copolymer of ethylene and tetrafluoroethylene (X‐ETFE) was conducted to determine the chemical changes taking place during thermal aging. These studies provided insight into the roles of the various additives, such as triallylisocyanurate (TAIC) and antimony oxide, in the formulated X‐ETFE insulation. During irradiation processing, a large fraction of the TAIC is converted to a cross‐linked isocyanurate moiety; the unconverted TAIC is released during aging. Thermal aging of the X‐ETFE wire insulations was performed in air at 200°C for up to 5 months and resulted in oxidation of the base ETFE, loss of unreacted TAIC, and a small amount of dehydrofluorination. The antimony oxide serves the multiple roles of flame retardant and scavenger for the pyrolytically generated hydrogen fluoride.