Hole size distributions in cardo-based polymer membranes deduced from the lifetimes of ortho-positronium

The International Workshop on Positron Studies of Defects 2014

Kobayashi, Y.^1,3 ; Kinomura, A.^1,6 ; Kazama, S.^2 ; Inoue, K.^3 ; Toyama, T.^3 ; Nagai, Y.^3 ; Haraya, K.^4 ; Mohamed, H.F.M.^5 ; O'Rourke, B.E.^1 ; Oshima, N.^1 ; Suzuki, R.^1

Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology, Ibaraki, Tsukuba

305-8568, Japan^1

Nippon Steel and Sumitomo Metal Corporation, Technical Development and Planning Division, 6-1 Marunouchi, 2 chome, Chiyoda-ku, Tokyo

100-8701, Japan^2

Oarai Center, Tohoku University, Oarai, Ibaraki, 311-1313, Japan^3

Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology, Ibaraki, Tsukuba

305-8565, Japan^4

Physics Department, Faculty of Science, Minia University, P. O. Box 61519, Minia, Egypt^5

Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka

590-0494, Japan^6

关键词: Hexafluoropropane dianhydride (6FDA);    Hole size distribution;    Increasing temperatures;    Polyimide membranes;    Polymer membrane;    Polysulfone membranes;    Thermal expansion coefficients;    Volume size distribution;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/674/1/012017/pdf
DOI  :  10.1088/1742-6596/674/1/012017

来源: IOP

【 摘 要 】

To clarify the free volume size distributions of the cardo-based polymer membranes, where ortho-positronium (o-Ps) undergoes pick-off annihilation, the o-Ps lifetime distributions were analyzed by the LT9 programme. It was found that the cardo-based polysulfone membrane has much narrower o-Ps lifetime/hole size distributions than the cardo-based polyimide membranes with the 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) moiety. Further, the lifetime/hole size distributions of the cardo-based polymer membranes are appreciably broadened with increasing temperature. This suggests that in these membranes there are holes not only of different sizes but also of different thermal expansion coefficients. It is also shown that in a membrane with a wider hole size distribution the average o-Ps lifetime tends to be longer than would be expected from the correlation between the o-Ps lifetime and the total free volume for common polymers.