An experimental study of erosion effects on polyimide in atomic oxygen environment

The erosion behaviors of polymeric materials and polymer-based composites have been studied during exposure in atomic oxygen (AO) environment in the ground-based simulation facility. The in situ testing analysis for the dependence of the erosion rate of polyimide film upon the impingement angle of AO was made by using a quartz crystal microbalance (QCM). The variations of chemical and physical properties of sample surfaces after exposed to AO fluxes were investigated by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). Collisions of high active AO with spacecraft surfaces result in oxidation and erosion of spacecraft materials. When exposed to AO, polyimide films undergo remarkable mass loss and surface significant roughening. The results of our experimental studies demonstrated that the carbonyl group in Kapton reacted with oxygen atoms to emit CO and/or CO₂, they desorbed from Kapton surface as gas state, which was the major reason for materials degradation during AO exposure of polymer-based materials. In situ mass loss measurements during atomic oxygen beam exposure clearly indicated that the impingement angle dependence of the erosion rate of polyimide follow a cosine law.