Polyimide degradation under atomic oxygen attack

Abstract

Procedures are developed for accelerated laboratory tests of spacecraft polymers for resistance to long-term exposure to hyperthermal atomic oxygen (AO) with the use of high-energy AO ions of a rarefied plasma and Kapton-H polyimide as the reference material. The parameters that characterize physico-chemical, thermo-optical, and aerodynamic AO – Kapton-H interaction (surface roughness, solar absorptance, and normal infrared emittance) are determined at different values of the AO fluence. To do this, use was made of the data of tests onboard spacecraft in the Earth's atmosphere and the authors and others' laboratory tests. The normal and the tangential momentum transfer coefficient and the energy transfer coefficient are reported as a function of the AO bombardment angle. The obtained data on the AO-induced degradation of the parameters that characterize AO–polyimide dynamic interaction allow one to predict the behavior of the polyimide thermo-optical and aerodynamic properties during a long-term service in the Earth's upper atmosphere and ionosphere.