21-25 July 2019
Connecticut Convention Center, Level 6
US/Eastern timezone

C4Or1C-06: Helium Permeation through Polymer Films at Cryogenic Temperatures

25 Jul 2019, 10:45
15m
Level 6, Room 24-25 ()

Level 6, Room 24-25

Speaker

Kjell Westra (Hydrogen Properties for Energy Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164-2920 USA)

Description

The implementation of polymer films as cryogenic propellant bladders could mitigate sloshing in a microgravity environment. However, prior research into cryogenic bladders was discontinued in the 1970s due to reportedly high permeabilities of hydrogen and helium through polymer films at cryogenic temperatures. These permeabilities differed from the Arrhenius relation by increasing as temperatures lowered. A hypothesis for this increase was that the comparatively large thermal de Broglie wavelengths of hydrogen and helium at cryogenic temperatures allowed for an increased particulate hopping rate and bulk permeation. Testing of this hypothesis was completed by characterizing the helium permeability of PET, Kapton, Ultem, PEEK, and EVOH polymer films between 190 – 30 K with a calibrated helium mass spectrometer. Results indicate that the permeabilities of each polymer followed the Arrhenius relation until permeation rates dropped below the sensitivity of the mass spectrometer. Below 100 K, the permeabilities were negligible: under this threshold, the design of cryogenic bladders is insensitive to the permeabilities of these films. An explanation for why the historic permeation measurements likely deviated from Arrhenius type behavior is also provided.

Primary author

Kjell Westra (Hydrogen Properties for Energy Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164-2920 USA)

Co-author

Dr Jacob Leachman (Hydrogen Properties for Energy Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164-2920 USA)

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