Casting solvent effects on morphologies, gas transport properties of a novel 6FDA/PMDA-TMMDA copolyimide membrane and its derived carbon membranes

Lu Shao, Tai-Shung Chung, Glen Wensley, Suat Hong Goh, Kumari Pallathadka Pramoda

Research output: Contribution to journalArticlepeer-review

94 Scopus citations

Abstract

We have observed that solvents play an important role on the membrane morphology and gas separation performance of a novel 6FDA/PMDA-TMMDA copolyimide [copoly(4,4'-methylenebis(2,6-dimethyl)-2,2-bis(3,4-dicarboxylphenyl) hexafluoro propane/pyromellitic) diimide]. Copolyimide films cast from CH 2Cl 2 or NMP (1-methyl-2-pyrrolidinone) show amorphous morphology, while films cast from DMF (N,N-dimethylformamide) have crystalline structure which has been confirmed by polarized microscope, XRD and gas sorption tests. Gas transport properties of different morphological films are significantly different. Furthermore, we also report that gas separation performance of carbon molecular sieve membranes (CMSMs) pyrolyzed from different morphological precursors is strongly dependent on pyrolysis temperatures. Results show that the permeability of CMSMs at different pyrolysis temperatures follows the order: 550°C > 650°C > 800°C and the separation factor is in the order: 800°C > 650°C > 550°C. The differences between CMSMs derived from different morphological precursors decrease with an increase in pyrolysis temperatures. At low pyrolysis temperature, the CMSMs' structure and separation performance could significantly be affected by the decomposition temperature of the precursor, however, at higher pyrolysis temperatures, the dominant factor for the CMSMs' structure and performance is the pyrolysis temperature due to the complete degradation of the polymeric precursor.

Original languageEnglish (US)
Pages (from-to)77-87
Number of pages11
JournalJournal of Membrane Science
Volume244
Issue number1-2
DOIs
StatePublished - Nov 15 2004

Keywords

  • Carbon molecular sieve membranes (CMSMs)
  • Crystalline structure
  • Fluoropolyimides
  • Gas separation
  • Solvent effect

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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