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Title: Synthesis, cross-linking modifications of 6FDA-NDA/DABA polyimide membranes for ethanol dehydration via pervaporation
Authors: Le, N.L.
Wang, Y. 
Chung, T.-S. 
Keywords: 6FDA-NDA/DABA polyimide membrane
Diamino cross-linking
Diol cross-linking
Ethanol dehydration
Thermal cross-linking
Issue Date: 1-Oct-2012
Citation: Le, N.L., Wang, Y., Chung, T.-S. (2012-10-01). Synthesis, cross-linking modifications of 6FDA-NDA/DABA polyimide membranes for ethanol dehydration via pervaporation. Journal of Membrane Science 415-416 : 109-121. ScholarBank@NUS Repository.
Abstract: A novel polyimide, copoly(1,5- naphthalene/3,5-benzoic acid-2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropanedimide (6FDA-NDA/DABA), has been synthesized and modified via various cross-linking modifications for ethanol dehydration as a pervaporation membrane. Three different cross-linking approaches - thermal, diamino and diol cross-linking modifications - are employed; their effects on membrane morphology and separation performance are investigated with the help of various characterization techniques. Thermal treatment at high temperature (425 °C) facilitates the decarboxylation-induced cross-linking, therefore restricting the membrane swelling, creating a higher d-space among polymer chains, and contributing to high permeation fluxes and comparable separation factors of the resultant membranes for ethanol dehydration. Diamino cross-linking modification changes imide groups in the polyimide into amide groups but post heat-treatment converts them back. However, the interactions among polymer chains are irreversibly changed by the formation of chemical cross-linking and charge transfer complexes, as well as the enhanced hydrophilicity, which bring out the improvement in membrane performance. Diol cross-linking also constrains the membrane swelling and results in a higher d-space by the cross-linking spacer, and therefore leading to a higher flux but a lower separation factor than membranes modified by the above two other methods. This work may provide useful insights for polyimide synthesis and cross-linking modifications for biofuel separation. © 2012 Elsevier B.V.
Source Title: Journal of Membrane Science
ISSN: 03767388
DOI: 10.1016/j.memsci.2012.04.042
Appears in Collections:Staff Publications

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