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 containing polyimide, 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 the production of small molecules. The results show that the water will encourage the degradation of the main chains of polyimide by aggravating the broken imide ring. Meanwhile, the water molecules represent the humidity, which would reduce the initial decomposition temperature with the number.

kapton,humidity,thermal-oxygen,pyrolysis,ReaxFF MD