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 language | English (US) |
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Pages (from-to) | 267-278 |
Number of pages | 12 |
Journal | Journal of Membrane Science |
Volume | 330 |
Issue number | 1-2 |
DOIs | |
State | Published - Mar 2 2009 |
All Science Journal Classification (ASJC) codes
- Biochemistry
- General Materials Science
- Physical and Theoretical Chemistry
- Filtration and Separation
Keywords
- Melt processing
- Nucleated polypropylene
- Polypropylene
- Solvent-resistant microporous membrane
- Spherulite