Polyhedral Oligomeric Silsesquioxane (POSS) Polyimides as Space-Survivable Materials (Preprint)
Abstract
Polyimides (PIs) such as Kapton(R) are used extensively in spacecraft thermal blankets, solar arrays, and space inflatable structures. Atomic oxygen (AO) in low Earth orbit (LEO) causes severe degradation of Kapton(R). SiO(sub 2) coatings impart remarkable oxidation resistance and have been widely used to protect Kapton(R), yet imperfections in the SiO(sub 2) application process and micrometeoroid/debris impact in orbit damage the SiO(sub 2) coating leading to Kapton(R) erosion. A polyimide that is self-passivating by the formation of a silica layer upon exposure to AO has been achieved by the copolymerization of a polyhedral oligomeric silsesquioxane (POSS) diamine with the Kapton(R) monomers, pyromellitic dianhydride and 4,4'-oxydianiline, resulting in POSS-Kapton(R)-polyimide. The self-passivating properties have been shown by monitoring a 1 micron deep scratch in POSS-PIs after exposure to AO. Kapton H(R), SiO(sub 2)-coated Kapton HN(R), and 8.75 weight % Si(sub 8)O(sub 11) cage "main-chain" POSS-polyimide (8.75 wt % Si(sub 8)O(sub 11) MC-POSS-PI) were exposed to equivalent AO fluences before and after being scratched. During the first AO exposure and outside of the scratch, these samples eroded 5.0 microns, 0 microns, and less than 200 nm respectively. During the second AO exposure, the samples eroded an additional 5.0 microns within the scratch and outside of the scratch, 7.0 microns within the scratch and 0 microns outside of the scratch, and 200 nm within the scratch and 0 microns outside of the scratch respectively.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 27, 2006
- Accession Number
- ADA455720
Entities
People
- Amy L. Brunsvold
- Andrew J. Guenthner
- Brian J. Petteys
- Darrell Marchant
- Gregory R. Yandek
- Joe Mabry
- Michael El Wright
- Sandra J. Tomczak
- Timothy K. Minton
- Vandana Vij
Organizations
- Air Force Research Laboratory