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Title: Characterizing free volumes and layer structures in polymeric membranes using slow positron annihilation spectroscopy
Authors: Jean, Y.C.
Chen, H.
Zhang, S.
Chen, H. 
Lee, L.J.
Awad, S.
Huang, J.
Lau, C.H. 
Wang, H. 
Li, F. 
Chung, T.-S. 
Issue Date: 2011
Citation: Jean, Y.C., Chen, H., Zhang, S., Chen, H., Lee, L.J., Awad, S., Huang, J., Lau, C.H., Wang, H., Li, F., Chung, T.-S. (2011). Characterizing free volumes and layer structures in polymeric membranes using slow positron annihilation spectroscopy. Journal of Physics: Conference Series 262 (1) : -. ScholarBank@NUS Repository.
Abstract: Positron annihilation spectroscopy coupled with a newly built slow positron beam at National University of Singapore has been used to study the free volume, pore, and depth profile (0 - 10 μm) in cellulose acetate polymeric membrane at the bottom and top sides of membranes for ionic separation in water purification applications. The S and R parameters from Doppler broadening energy of annihilation radiation representing free volumes (0.1-1 nm size) and pores (>1 nm-μm) as a function of depth have been analyzed into multilayers, i.e. skin dense, transition, and porous layers, respectively. The top side of membrane has large free volumes and pores and the bottom side has a skin dense layer, which plays a key role in membrane performance. Positron annihilation lifetime results provide additional information about free-volume size and distribution at the atomic and molecular scale in polymeric membrane systems. Doppler broadening energy and lifetime spectroscopies coupled with a variable mono-energy slow positron beam are sensitive and novel techniques for characterization of polymeric membrane in separation applications. © 2011 IOP Publishing Ltd.
Source Title: Journal of Physics: Conference Series
ISSN: 17426588
DOI: 10.1088/1742-6596/262/1/012027
Appears in Collections:Staff Publications

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