Characterization of Ultra Low Outgassing^TM Silicone Materials for Aerospace Applications  

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Bill Riegler, Product Director-Engineering Materials,
Brian Burkitt, Sr Technical Sales-Engineering Materials,
Rob Thomaier, Research Director,
NuSil Technology LLC, Carpinteria, CA 93013

Presented at the 2007 SAMPE Conference, June 3-7, Baltimore, MD

ABSTRACT

The Aerospace Industry has used silicone adhesives and coatings for over five decades1. Silicones ability to maintain its elasticity and low modulus over a broad temperature range, –130 to 260°C, provides excellent utility in space, where spacecraft are often exposed to these extreme temperatures. The National Aeronautics & Space Administration (NASA) and the European Space Agency (ESA) recommend testing low outgassing materials per ASTM E-595 prior to use in space. 2 These materials should meet the specifications outlined in NASA SP-R-0022A and ESA PSS-014-702, which require a maximum Total Mass Loss (TML) of 1% and Collected Volatile Condensable Material (CVCM) of 0.1%3,4. TML and CVCM levels higher than this specification can cause outgassing and subsequent contamination of expensive equipment. Although a standard for many years, many in the industry question whether these specifications are low enough.

Boeing Satellite suspects gaseous emission contamination has caused excessive power degradation on six 702 satellites.5, 6 The large solar panel temperatures reach greater than 120C and surface temperature strongly affects contamination buildup and can volatilize larger molecules.7 The Aerospace Corporation performed a contamination analysis comparing two different temperature solar arrays. This comparison showed high temperature arrays can contaminate to a greater degree.8 This paper will characterize newly developed ultra low outgassing™ materials with TML and CVCM one-tenth the previous specifications. Characterization will include physical, outgas, and optical testing and comparisons will be made to standard materials meeting the basic outgassing requirements.

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