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Degradation of Intercalated Graphite Epoxy Composites Exposed to Low Earth OrbitFour different graphite fiber/epoxy composites were exposed to the wake-side low Earth orbit (LEO) environment on the Optical Reflector Materials Experiment III (ORMatE-III) platform mounted on the exterior of the ISS for two years in order to determine their long term durability in the space environment. Three of the composite samples used bromine intercalated P100 fibers and one used pristine P100 fibers. One of the P100-Br samples was coated with a protective SiO2 layer, and half of another was coated with SiO2. Results were compared with the EOIM-III experiment which exposed the same materials in LEO in the ram direction for 42 h on the Space Shuttle. Although the atomic oxygen (AO) fluence of the ORMatE-III samples was one-third of the EOIM-III exposure, the resulting effects were qualitatively the same. Both found that SiO2 coated intercalated graphite composites showed no AO erosion, verifying that conventional protection strategies are applicable to bromine intercalated composites. Both found that bromine intercalation does not alter the AO erosion rates of graphite fiber/epoxy composites. Both found no bromine was detected to have migrated into the surrounding epoxy, even for highly eroded fibers and epoxy, allaying fears that bromination could compromise the properties of the epoxy. And both found no corrosive bromine was detected to have been released by the fibers allaying fears that outgassing could degrade sensitive electronics. The uncoated EOIM-III samples suffered slightly greater erosion resulting in a slightly higher solar absorptance. The general conclusion is that ram AO exposure had very similar effects on graphite fiber epoxy composites in both the EOIM-III and ORMatE-III experiments, and in neither case did bromine intercalation of the fibers substantially influence that degradation.
Document ID
20180005315
Document Type
Technical Memorandum (TM)
Authors
Gaier, James R. (NASA Glenn Research Center Cleveland, OH, United States)
De Groh, Kim K. (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
September 17, 2018
Publication Date
July 1, 2018
Subject Category
Composite Materials
Report/Patent Number
E-19544
GRC-E-DAA-TN57237
NASA/TM-2018-219928
Funding Number(s)
WBS: WBS 811076.01.04.01.05
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Intercalated graphite
composite
LEO
durability

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