Investigation into tolerance of polysiloxane-block-polyimide film against atomic oxygen

摘要

Silicon containing polyimide is proposed as an atomic-oxygen (AO)-tolerant material for Low Earth Orbit flight. For this study, commercially available polysiloxane-block-polyimide film is selected for investigation. An AO beam is irradiated on the polysiloxane-block-polyimide film at the Combined Space Effects Test Facility of JAXA in Tsukuba, Japan. To investigate the AO tolerance, mass change measurement, cross-sectional transmission electron microscopic (TEM) observation, and X-ray photoelectron spectroscopic (XPS) analysis are performed. Results show that the mass loss of polysiloxane-block-polyimide is one one-hundredth or less than that of Kapton~® H: Cross-sectional TEM observation and XPS analysis reveals that the AO protective SiO_2 layer is self-organized by AO irradiation. Furthermore, the self-organized SiO_2 layer is intentionally damaged to investigate reorganization of a new layer on it. Further AO irradiation of the damaged surface revealed that the new layer is built with a 500-nm-deep eroded region. The result verifies the "self-healing" ability of polysiloxane-block-polyimide. These results suggest that polysiloxane-block-polyimide film has high potential to provide many advantages of a space-use material, especially for LEO spacecraft.