Development of asymmetric hollow fibers from polyimides for air separation

Tai Shung Chung*, E. Ronald Kafchinski, Paul Foley

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

86 Scopus citations


We have developed 6FDA/6FDAM polyimide hollow fibers with a selectivity of 6.7 for O2/N2 and a permeance of 8.3×10-6 cc(STP)/cm2-sec-cmHg. The dense layer thickness was about 1000-1900 Å. These hollow fibers were dry-jet wet-spun from a 42% low IV (intrinsic viscosity)6FDA/6FDAM polyimide/N-methyl-pyrrolidone (NMP)/propionic acid (PA) (57/43) dope using methanol as a coagulant and 80/20 NMP/H2O as a bore fluid. The hollow fiber must be coated with a silicone elastomer. The fiber diameter was about 215 μm with a wall thickness about 25-30 μm. SEM observation showed that the dense layer was located at the outer surface, while the region near the inner surface had an interconnceted open-cell structure. The total void percentage in this fiber was about 60%. The calculated Hildebrand parameter for this study was about 2.3 to 2.99 (cal/cm3)0.5 between the NMP:PA solvent complex and the polyimide. The first Tg for our 6FDA/6FDAM polyimide hollow fiber was much lower than the Tg of its bulk, or second Tg.

Original languageEnglish (US)
Pages (from-to)181-195
Number of pages15
JournalJournal of Membrane Science
Issue number1-2
StatePublished - Dec 16 1992


  • air separation
  • asymmetric membranes
  • hollow fiber membranes

ASJC Scopus subject areas

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


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