Self-Passivation of POSS-Kapton-Polyimides in the Presence of Atomic Oxygen (Preprint)

Abstract : Evidence for the formation of a protective silica layer on the surface of POSS-Kapton(Registered)-PIs upon exposure to AO was found in X-Ray Photoelectron Spectroscopy (XPS) studies of POSS-Kapton(R)-PIs flown on the Materials International Space Station Experiment (MISSE1), and in separate studies of POSS-Kapton(R)-PIs exposed to AO in a ground-based facility. To directly compare the effect of AO on Kapton H(R), SiO2 coated Kapton HN(R), and 8.75 weight % Si8O11 cage "main-chain" POSS-Kapton(R)-polyimide (8.75 wt % Si8O11 MC-POSS-PI), these materials were exposed to AO, scratched, and exposed to a second equivalent AO fluence. The erosion of the three materials, inside and outside of the scratched area, was monitored by stylus surface profilometry. The results of this study indicate that the POSS Kapton(R) PI reproducibly eroded about 200 nm before forming a silica layer. A thin film of 7 wt % Si8O11 survived a 3.9 year flight on the MISSE1, on the International Space Station which resides at 500 km in LEO. The effects of temperature, physical property characterizations, and the MISSE1 flight will be discussed.