Degradation Property of Commercially Available Si-containing Polyimide in Simulated Atomic Oxygen Environments for Low Earth Orbit

Abstract

Real-time measurement of the erosion rate of a commercially available Si-containing polyimide (BSF30) under hyperthermal atomic oxygen (AO) beam exposure condition, which simulates the AO environment in low Earth orbit (LEO), was performed. It was found that the erosion rate of BSF30 decreased with increasing AO fluence and it reached as low as 4% of the standard PMDA-ODA polyimide. X-ray photoelectron spectroscopy confirmed that the surface of AO-exposed BSF30 was covered by a SiO2 layer which functioned as a protective coating. In contrast, an SiO2 surface layer thick enough to protect bulk BSF30 was not formed by thermal AO, which was generated by vacuum ultraviolet exposure in an O2 atmosphere. Exposure to hyperthermal AO collision in LEO can also form an SiO2 layer which enables the surface to be self-healing and is desirable for a polyimide that would be used in LEO.