Rheological investigations of linear and hyperbranched polyethersulfone towards their as-spun phase inversion membranes' differences
Yang, Q. Chung, T.-S. Weber, M. Wollny, K.
Weber, M.
Wollny, K.
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Abstract
We have investigated the macromolecular structure and rheological behavior of both linear and hyperbranched polyethersulfone (PES) materials. It was found that the hyperbranched PES material has a higher molecular weight and a wider molecular weight distribution than its linear analogue. Rheological studies disclose that polymer solutions made from the HPES/polyvinylpyrrolidone (PVP)/N-methyl-2-pyrrolidone (NMP) ternary system have a longer relaxation time than their linear counterparts. The less relaxation characteristics of the HPES dope not only result in a more pronounced die swelling during hollow fiber spinning, but also produce hollow fiber membranes with smaller pore sizes, narrower pore size distribution, and a smaller molecular weight cut-off (MWCO). In addition, elongational viscosity characterizations indicate that HPES possesses a more strain hardening effect than LPES. As a result, films made from the former tends to break easier and quicker under high extensional strains than those made from the latter. © 2008 Elsevier Ltd. All rights reserved.
Keywords
Polyethersulfone, Polymer processing, Polymer rheology
Source Title
Polymer
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Series/Report No.
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Date
2009-01-16
DOI
10.1016/j.polymer.2008.11.039
Type
Article