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Title: Permeability of polyimides derived from non-coplanar diamines and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride
Authors: Xu, J.W.
Chng, M.L. 
Chung, T.S. 
He, C.B.
Wang, R.
Keywords: 6FDA-polyimide
Gas separation
Issue Date: 10-Jul-2003
Citation: Xu, J.W., Chng, M.L., Chung, T.S., He, C.B., Wang, R. (2003-07-10). Permeability of polyimides derived from non-coplanar diamines and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride. Polymer 44 (16) : 4715-4721. ScholarBank@NUS Repository.
Abstract: A series of polyimides including a non-coplanar moiety were synthesized in order to investigate the effect on gas permeability and selectivity. The gas permeation properties of He, H2, O2, N2, CH4 and CO2 were measured using a constant-volume method. Only 6FDA-terphenyl consisting of laterally attached phenyl groups shows a substantial increase because its terphenyl moiety is a rigid structure with a high aspect ratio. The order of permeability increase from 6FDA-phenyl to 6FDA-terphenyl is consistent with the calculated fraction free volume and measured permittivity. It is observed that the most gain in permeability for 6FDA-terphenyl polyimide arises from the enhancement in apparent diffusion coefficient, while the permeability increase for 6FDA-biphenyl is mainly due to the increase in solubility. A relationship of diffusivity vs. gas penetrant size as well as gas solubility vs. critical temperature of gas penetrant was also investigated. © 2003 Elsevier Science Ltd. All rights reserved.
Source Title: Polymer
ISSN: 00323861
DOI: 10.1016/S0032-3861(03)00430-0
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