Engineers perform outgassing tests to evaluate material performance within controlled, high-precision environments. Many polymers, coatings, adhesives, and composite materials retain traces of solvents or gaseous absorbents that they emit over time. These emissions can lead to optical contamination, pressure instability, or malfunction of neighboring constituents. Engineers use standard test procedures to measure the amount of gas released under defined conditions. Proper measurement will enable the proper choice of materials and assist with quality control in any industry where environmental control is important.
Understanding Outgassing Behavior
Outgassing is a process in which volatile substances leave the bulk of a material and migrate to its surface, where they leak out. This behavior is very sensitive to temperature, pressure, material composition, and surface finish. Lower external pressure increases the outgassing rate of materials in vacuum conditions. Moisture absorption also causes mass loss during testing. Knowledge about the factors aids in forecasting material behavior under the actual conditions of operation.
Key Parameters Measured During Outgassing Testing
Outgassing tests focus on measurable parameters. The total mass loss (TML) measures the total amount of volatiles lost during exposure. Technicians determine the percentage of condensable material on colder surfaces by collecting volatile condensates, which directly indicates the risk of contamination. Engineers use Water Vapor Regain (WVR) to assess a material’s ability to reabsorb water after testing. Analysts maintain tight control over test temperatures, exposure times, and vacuum levels to guarantee consistency and reproducibility. Collected Volatile Condensable Material (CVCM) is another critical metric being determined during the outgassing test. CVCM evaluates how much of a material’s outgassed substance vaporizes and condenses onto nearby surfaces
