Impacts of moisture on the thermal-oxygen pyrolysis of Kapton, a ReaxF MD simulation

Kapton-type polyimide films are always used as the solid insulation medium in many power-electronic devices, which will decompose due to the high temperature caused by the partial discharge in the open air. In order to explore the influence of moisture on the thermal-oxygen decomposition characteristics of Kapton, simulation models containing1polyimide, oxygen and water molecules are established in this paper. The ReaxFF molecular dynamics simulation is applied to indicate the pyrolysis process of polyimide, as well as the changes in production of small molecules. The results show that the moisture will encourage the degradation of main chains of polyimide by aggravating the broken of imide ring. And in the short effect of unbalanced PD, the benzene ring the Kapton could not be broken.