Offgassing/Outgassing

In aerospace applications, material candidates are often screened for outgassing and offgassing properties.Outgassing isthe release of chemicals from non-metallic substances under vacuum conditions. Test method ASTM E595 is routinelyused to assess material outgassing characteristics. In this test, a material is held at 125°C for 24 hours in vacuum,andcondensing volatiles are collected on a cooled plate.Test results include the sample’s percent total mass loss (TML%), the percent collected volatile condensable materials (CVCM%), and percent water vapor regained (WVR%).

Offgassing refers to the release of chemicals from materials at ambient or higher pressure. Test method NHB 8060.1C (Test 7) is commonly used to measure offgassing characteristics.In this test,the candidate material is held at 125°C andambient pressure for 72 hours.Gas sample analysis yields offgassed product identities and their concentration. For eachspecies,the ratio of the sample concentration to its SMAC (spacecraft maximum allowable concentration) is calculated. The sum of these ratios is the T value of the material, or the Toxic Hazard Index.

Vectran™ fiber with either T97 or T150 finish provides excellent offgassing and outgassing characteristics (Table 7) in awide variety of aerospace applications.