Study of low outgassing materials used for spacecraft: Composition and outgassing characterization
Room-temperature vulcanized (RTV) silicone polymers are very important for bonding in spacecraft, but they produce outgassing products which may condense on optical instruments and thermal control surfaces and degrade their performance and shorten the lifetime of spacecraft. Until now, nobody has solved the silicone polymer outgassing problem on spacecraft. The primary objective of this dissertation is to study some broadly used low outgassing silicone polymers and find out if one or two selected materials would work to predict the optical constants and contamination behaviors of the outgassing products from silicone polymers. We studied on these five commonly used silicone polymers: CV2568, RTV566, DC93-500, SCV2590 and SCV2590-2. Raman spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy were applied to study their compositions; while their outgassing products and outgassing rates were determined by FTIR. Secondly, films formed from pure Poly(dimethylsiloxane) (PDMS), Tetra-n-propylsilicate (NPS), and their mixtures with various volume ratios were studied via Field Emission Scanning Electron Microscope (FE-SEM), profilometry, surface enhanced Raman spectroscopy (SERS) and ellipsometry to determine the outgassing products properties. The effects of VUV input power, deposition time and cell temperature on the films formation and their optical properties were studied and discussed in detail. Finally, the experimental data of films formed from PDMS, NPS and their mixtures with one factor varying were modeled together to determine how they change the optical property of each material in both visible to NIR and IR wavelength ranges. The thickness and optical constants data of outgassing products in this dissertation are valuable for system performance evaluation and lifetime prediction, and they could also be used as the guideline for choosing low outgassing silicone polymer, optimizing the compositions and ratios of compositions in low outgassing silicone polymers.
Polymer chemistry|Electrical engineering|Materials science
Hanrahan, Fen Zhou, "Study of low outgassing materials used for spacecraft: Composition and outgassing characterization" (2013). ETD collection for University of Nebraska - Lincoln. AAI3557985.