Flammability Behaviour of Polydimethylsiloxane (PDMS) Membranes Under Normoxic Conditions for Spacecraft Applications

Ulises Rojas-Alva, Frederik Møller-Poulsen, Grunde Jomaas

Research output: Contribution to conferencePaperpeer-review

Abstract

Two types of polydimethylsiloxane PDMS membranes with two thicknesses, 0.125 mm and 0.25 mm, were studied experimentally for a series of environmental conditions in a closed chamber. The conditions were changing oxygen concentration, ambient pressure and normoxic conditions. The results for piloted ignition are linearly dependent on oxygen concentration and ambient pressure via chemistry. A non-monotonic dependency was found in normoxic conditions, but the dominant mechanisms are not clear. The flame spread has a linear dependence on oxygen concentration via chemistry and thermal transfer. Two dependency regimes (linear and asymptotic) emerge for flame spread as a function of ambient pressure. The mechanisms are due to thermal transfer (linear regime) and a combination of thermal transfer and kinetics (asymptotic regime). Flame lengths are exponentially dependent on oxygen concentration via oxygen/fuel supply and soot oxidation. On the contrary, ambient pressure affects flame length non-monotonically via fuel supply (increasing regime) and an excess of oxidiser (decreasing regime). Under normoxic conditions, increasing oxygen concentration had a stronger influence than decreasing pressure with respect to both flame spread and flame length. The extinction conditions at low pressure are due to a combination of increased radiative losses (similar to those of microgravity conditions) and kinetic effects. Furthermore, extinction at low pressures occurred well below normoxic or hypoxic conditions. Thus, the two PDMS materials tested are more flammable under normoxic conditions, which needs to be considered when assessing the fire risk associated with spacecraft design and operation. It remains unclear how these results directly translate to microgravity, where other phenomena might dominate, so future experiments in microgravity are recommended.
Original languageEnglish
Publication statusPublished - 19 Oct 2021
Event11th International Association for the Advancement of Space Safety Conference : Managing Risk In Space - Virtual Venue
Duration: 19 Oct 202121 Oct 2021
http://iaassconference2021.space-safety.org/

Conference

Conference11th International Association for the Advancement of Space Safety Conference
Abbreviated title11th IAASS Conference
Period19/10/2121/10/21
Internet address

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