Novel polypropylene-based microporous membranes via spherulitic deformation

K. Y. Lin, M. Xanthos, K. K. Sirkar

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

A novel method for creating a microporous membrane via spherulitic deformation is illustrated. The microporous structure was generated by the combination of intra-spherulitic and inter-spherulitic deformations. Polypropylene was selected due to its unique cross-hatched lamellar morphology facilitating inter-spherulitic deformation. A precursor film with a spherulitic structure was made under low-stress melt processing condition. A tangential lamellae-rich spherulite was created and identified with a positive birefringence sign. A sequential annealing process improved the crystalline structure, and in particular the thickness of the tangential lamellae. The annealing process proved to be critical for initiating the inter-spherulitic deformation. A WAXS examination provides a quick characterization method for the inter-spherulitic deformation. A highly interconnected solvent-resistant porous polypropylene membrane having a pore size in the range of 50-100 nm and a porosity of about 0.18 was thereby developed in this study. This concept can be further expanded by using an α-nucleating agent to reduce spherulite sizes. A highly methanol permeable membrane with an estimated porosity of 0.29 was produced with the nucleated polypropylene samples.

Original languageEnglish (US)
Pages (from-to)267-278
Number of pages12
JournalJournal of Membrane Science
Volume330
Issue number1-2
DOIs
StatePublished - Mar 2 2009

All Science Journal Classification (ASJC) codes

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

Keywords

  • Melt processing
  • Nucleated polypropylene
  • Polypropylene
  • Solvent-resistant microporous membrane
  • Spherulite

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