Long-term permeation properties of poly(1-trimethylsilyl-1-propyne) membranes in hydrocarbon-vapor environment

I. Pinnau*, C. G. Casillas, A. Morisato, B. D. Freeman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

Poly(1-trimethylsilyl-1-propyne) (PTMSP), a high free-volume glassy disubstituted polyacetylene, has the highest gas permeabilities of all known polymers. The high gas permeabilities in PTMSP result from its very high excess free volume and connectivity of free volume elements. Permeability coefficients of permanent gases in PTMSP decrease dramatically over time due to loss of excess free volume. The effects of aging on gas permeability and selectivity of PTMSP membranes continuously exposed to a 2 mol % n-butane/98 mol % hydrogen mixture over a period of 47 days are reported. The permeation properties of PTMSP membranes are quite stable when the polymer is continuously exposed to a gas mixture containing a highly sorbing organic vapor such as n-butane. The n-butane/hydrogen selectivity was essentially constant for the 47-day test period at a value of 29, or 88% of the initial value of the as-cast film of 33. Condensable gases such as n-butane may serve as a "filler" in the nonequilibrium free volume of the polymer, thereby preserving the high level of excess free volume.

Original languageEnglish (US)
Pages (from-to)1483-1490
Number of pages8
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume35
Issue number10
StatePublished - 1997
Externally publishedYes

Keywords

  • Hydrocarbon vapors
  • Mixed gas permeation
  • Physical aging
  • Poly(1-trimethylsilyl-1-propyne)

ASJC Scopus subject areas

  • Materials Chemistry
  • Polymers and Plastics

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