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|Title:||Halo formation in asymmetric polyetherimide and polybenzimidazole blend hollow fiber membranes|
|Authors:||Chung, T.-S. |
|Source:||Chung, T.-S.,Zhen-Liang, X.L.,Huan, C.-H.A. (1999-07-15). Halo formation in asymmetric polyetherimide and polybenzimidazole blend hollow fiber membranes. Journal of Polymer Science, Part B: Polymer Physics 37 (14) : 1575-1585. ScholarBank@NUS Repository. https://doi.org/10.1002/(SICI)1099-0488(19990715)37:14<1575|
|Abstract:||For the first time, we have reported a halo (ring) formation occurred in the cross-section of integrally skinned asymmetric membranes. These membranes were wet-spun from solutions containing 30 and 33 wt % of 95/5 and 90/10 polyetherimide (PEI)/polybenzimidazole (PBI). Both Imaging X-ray Photoelectron Spectroscopy (XPS) and Dynamic Mechanical Analyzer's (DMA) data suggest PEI and PBI form miscible blends the 'halo' is not chemically different from the matrix and is most likely a physical phenomenon of unique pore morphology. In other words, uniform porosity was created in the middle of hollow fiber cross-section area, which performs as a filter for light transmission. We found that the addition of PBI in PEI/DMAc solution not only depresses the macrovoid formation, but also changes the precipitation path: nucleation growth vs. spinodal decomposition. The formation of a halo within a membrane is possibly due to the fact that a uniform nucleation growth occurs in the ring region during the early stage of phase separation because of high solution viscosity and diffusion controlled solvent-exchange process, and then separation grows in the mechanism of spinodal decomposition from small amplitude composition fluctuations.|
|Source Title:||Journal of Polymer Science, Part B: Polymer Physics|
|Appears in Collections:||Staff Publications|
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