The effects of spinning conditions on asymmetric 6FDA/ 6FDAM polyimide hollow fibers for air separation

Tai Shung Chung*, E. Ronald Kafchinski

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

122 Scopus citations


We have found that the chemistries of inner and external coagulants, gelation bath temperature, and air gap distance have profound effects on 6FDA-polyimde hollow-fiber morphology and performance. This 6FDA-polyimide is made of 50 mol % 2,2′-bis(3,4′-dicarboxyphenyl) hexafluoro propane dianhydride (6FDA) and 50 mol % 2,2′-bis(3-aminophenyl) hexafluoro propane (4,4′ 6F-diamine) (6FDAM). An increase in air gap distance tends to induce three-dimensional open-cell pore formation. Raising bath temperature has a similar effect. Multilayer finger-void structure can be completely eliminated if one properly chooses a bore-fluid flow rate and a gelation bath temperature. Experimental data demonstrate that the location of the dense layer can be shifted from the inner skin to the outer skin based on the chemistry (solubility parameter ) of coagulants. The location of finger voids is also dependent on the chemistry of coagulants, and the dense layer location may shift from the inner surface to the external surface or appear in both surfaces dependent on the differences in solubility and coagulation rate. A defect-free 6FDA/6FDAM polyimide fiber with a selectivity of 4.73 and a permeance of 38.1 GPU is produced.

Original languageEnglish (US)
Pages (from-to)1555-1569
Number of pages15
JournalJournal of Applied Polymer Science
Issue number8
StatePublished - Aug 22 1997
Externally publishedYes


  • 6FDA polyimide membranes
  • Air separation
  • Hollow-fiber membrane
  • Phase-inversion process

ASJC Scopus subject areas

  • General Chemistry
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry


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