PROTECTION OF POLYMERIC MATERIALS FROM ATOMIC OXYGEN IN LOW EARTH ORBIT

摘要

This paper describes a surface modification process for protecting polymers and polymers and materials (such as composites and paints) from atomic oxygen (AO) erosion in low earth orbit (LEO). The process is a three-stage procedure involving surface activation of the polymer by exposure to short wavelength ultra-violet (UV) radiation in ambient air, silylation of the material with a silicon-based compound (either in a wet bath or by spray), followed by a stabilization treatment in the same UV environment. It is shown that an outer layer composed of essentially a silicon-oxide material is formed, diffusing about 0.5 microns into the bulk. Since this layer is not a coating, no cracking or peeling has been observed alter thermal cycling or exposure to AO and UV radiation. Materials studied to-date include nylon, Kapton, Mylar, PEEK, epoxy-based graphite and Kevlar composites, and polyurethane-based thermal control paints. Results are presented on AO tests of these materials, which show that no measurable mass loss was observed. A predictive model for estimating AO erosion rates based on the polymer repeat unit structure is described. Comparisons with laboratory and space flight test data indicate that the model correlates reasonably well for a wide range of polymer materials.