What is Outgassing?
Outgassing is a property of non-metallic materials; namely polymers used in the fabrication of coatings, adhesives, and electronics potting compounds. Under conditions of either high temperature, low pressure, or both, polymers release vapors through sublimation that can end up condensing onto neighbouring equipment – such as lenses and sensors – rendering them inoperable. High vacuum environments like outer space present challenges where excessive outgassing can damage fragile sensors in probes, while in the medical field, outgassing is particularly problematic when trying to maintain a sterile environment. In response, NASA developed a screening tool to gauge a material’s outgassing performance which the American Society for Testing and Materials translated into ASTM E595.
Testing a Material for Outgassing
ASTM E595 was developed exclusively for evaluating the outgassing performance of a given material. The key properties comprising the standard are total mass loss (TML) and collected volatile condensable matter (CVCM). In this test, specimens are prepared and placed in a vacuum chamber held at 5×10-5 Torr and 125°C for 24 hours. NASA considers a material to be low-outgassing if TML < 1% and CVCM ≤ 0.1%. A basic schematic of the ASTM E595 setup is presented below.
Solutions for Applications Requiring Low Outgassing Materials
Fortunately, MG Chemicals offers products that meet NASA’s low-outgassing standard. Depending on your specific needs, we can provide a low-outgassing product that will work for you. Specifically, MG sells 1-part RTV sealants, 2-part RTV potting compounds, electrically conductive epoxy adhesives, and thermally conductive adhesives that are low-outgassing.
Please contact technical support ([email protected]) to discuss your specific requirements, and how we can meet them.