Thermal degradation of polyesterimide magnet wire

The thermal degradation mechanism of EI (polyester imide) film on copper and aluminum wire was investigated. The effects of the metallic conductor on the degradation behavior and diagnosis methods applied to the EI films are reviewed. The physico-chemical properties were evaluated using a thermogravimetric analyzer, a Fourier-transform infrared (FTIR) spectrophotometer with a pyrolytic gaschromatograph (PGC) with FTIR. The degradation of EI was found to be accelerated by the presence of copper. In the presence of copper, decomposition of imide and ester bonds occurred simultaneously, resulting in a decrease in the breakdown stress. The PGC method was found to be effective for the insulation diagnosis of EI and the analysis of degradation mechanisms