What is outgassing?

Outgassing describes the release of volatile components from a material into the environment. In the case of elastomers and plastics, this can be Plasticiser, residual monomers, solvents or other low-molecular substances. The outgassing can occur immediately after production or only during later use and, depending on the application, influences the material properties or the environment in which the component is used.

 

Influencing factors for outgassing

Outgassing occurs primarily with:

  • Material composition: Blends with plasticisers, volatile additives or low molecular weight components outgas to a greater extent
  • Cross-linking type: Addition-curing silicones (e.g. LSR) produce hardly any by-products, while cross-linked elastomers can release low levels of residual degradation products
  • Additives in excessively high doses: Excessive additives or plasticisers cannot be fully incorporated into the polymer matrix and therefore increase outgassing
  • Temperature: Elevated temperatures accelerate the release of volatile components
  • Vacuum/vacuum pressure: Under reduced pressure, volatile molecules can diffuse out of the material more easily

 

The problem of outgassing

  • Contamination of sensitive components: Deposits on sensors, optical surfaces or circuit boards can cause measurement errors, signal interference or optical impairments
  • Faults in vacuum applications: Under vacuum, substances diffuse out of the material particularly quickly and contaminate the environment
  • Odour and emission problems: Outgassing substances can produce undesirable odours or perceptible emissions
  • Hygiene and safety risks: In applications with food or body contact, outgassing substances can lead to sensory changes or contamination

 

Prevention of outgassing

  • Tempering or pre-drying the parts to allow residual components to outgas before the component is used
  • Use of low-outgassing elastomers such as addition-cured silicones (e.g. LSR) or high-quality VMQ- and FKM-qualities
  • LABS-free Compounds for painting applications
  • Avoid overdosing or poorly integrated fillers, as they can cause increased outgassing