Erosion Data from the MISSE 8 Polymers Experiment After 2 Years of Space Exposure on the International Space Station

• Published in: NASA Center for AeroSpace Information (CASI). Misc. Resources
• Main Authors: de Groh, Kim K, Banks, Bruce A, Asmar, Olivia C, Yi, Grace T, Mitchell, Gianna G, Guo, Aobo, Sechkar, Edward A
• Format: Web Resource
• Language: English
• Published: Hampton NASA/Langley Research Center 12.07.2016
• Subjects: Aerospace environments; Aluminizing; Atomic oxygen; Erosion; Experiments; Exposure; Fluence; Fluorinated ethylene propylenes; Fluoropolymers; Heating; International Space Station; Low earth orbits; Orientation; Polymers; Polytetrafluoroethylene; Polyvinyl fluorides; Solar radiation; Space stations; Titanium dioxide; Zenith

The Polymers Experiment was exposed to the low Earth orbit (LEO) space environment for 2.14 and 2.0 years as part of the Materials International Space Station Experiment 8 (MISSE 8) and the Optical Reflector Materials Experiment-III (ORMatE-III), respectively. The experiment contained 42 samples, which were flown in either ram, wake, or zenith orientations. The primary objective was to determine the effect of solar exposure on the atomic oxygen erosion yield (Ey) of fluoropolymers. This paper provides an overview of the experiment with details on the polymers flown, the characterization techniques used, the atomic oxygen fluence for each exposure orientation, and the LEO Ey results. The Ey values for the fluoropolymers range from 1.45 x 10(exp -25) cm(exp 3)/atom for white Tedlar Registered Trademark (polyvinyl fluoride with white titanium dioxide pigment) flown in the ram orientation to 6.32 x 10(exp -24) cm(exp 3)/atom for aluminized-Teflon Registered Trademark fluorinated ethylene propylene (Al-FEP) flown in the zenith orientation. Erosion yield data for FEP flown in ram, wake and zenith orientations are compared, and the Ey was found to be highly dependent on orientation, hence environmental exposure. Teflon FEP had an order of magnitude higher Ey when flown in the zenith direction (6.32 x10(exp -24) cm(exp3)/atom) as compared to the ram direction (2.37 x 10(exp -25) cm(exp 3)/atom). The Ey of FEP was found to increase with a direct correlation to the solar exposure/AO fluence ratio showing the effect of solar radiation and/or heating due to solar exposure on FEP erosion. In addition, back-surface carbon painted FEP (C-FEP) flown in the zenith orientation had a significantly higher Ey than clear FEP or Al-FEP further indicating that heating has a significant impact on the erosion of FEP, particularly in the zenith orientation.