Finger-like voids induced by viscous fingering during phase inversion of alumina/PES/NMP suspensions

Bo Wang, Zhiping Lai

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

The formation mechanism of phase-inversion ceramic hollow fibre membranes has not been well understood. In this paper, we report on the formation of finger-like macrovoids during non-solvent-induced phase inversion of alumina/PES/NMP suspensions. A membrane structure without such finger-like macrovoids was observed when the suspension was slowly immersed into pure ethanol or a mixture of 70. wt% NMP and 30. wt% water, whereas finger-like macrovoids occurred when the suspension was slid into the non-solvents at higher speeds. We found that the formation process of finger-like macrovoids could be fully or partially reversed when nascent membranes were taken out from water shortly after immersion, depending on the duration of the immersion. Splitting of the fingers during the formation of the macrovoids was also observed during the phase inversion of two alumina/PES/NMP suspensions. These experimental observations were not predicted by current theories of finger-like macrovoid formation in polymer membranes, but appear to mimic the well-known viscous fingering phenomenon. We therefore propose that in the phase inversion of ceramic suspensions, the viscous fingering phenomenon is an important mechanism in the formation of finger-like voids. © 2012 Elsevier B.V.
Original languageEnglish (US)
Pages (from-to)275-283
Number of pages9
JournalJournal of Membrane Science
Volume405-406
DOIs
StatePublished - Jul 2012

ASJC Scopus subject areas

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

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