Free-volume study of ethylene - vinyl alcohol copolymer evaluated through positronium lifetime measurement |
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| Authors: | K. Ito Li Hong-ling Y. Saito T Yamamoto Y. Nishihara Y. Ujihira K. Nomura |
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| Affiliation: | (1) Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan;(2) Department of Environmental Sciences, Japan Atomic Energy Research Institute (JAERI), Tokai, Naka-gun, Ibaraki, 319-1195, Japan;(3) Physics and Analysis Research Center, Central Research Laboratory, The Nippon Synthetic Chemical Industry Co., Ltd, 13-1, Muroyama 2-chome, Ibaraki, Osaka, 567-0052, Japan;(4) School of Engineering, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656 |
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| Abstract: | The free-volume, of size ranging from 0.2 to 0.4 nm in radius, in an ethylene-vinyl alcohol copolymer was estimated using positronium lifetime measurement to elucidate the dependence of oxygen permeability on the free-volume size and fraction, on the ethylene content and on the crystallinity. The permeability and the free-volume fraction with varying the ethylene content were well related and the relation was interpreted based on the free-volume theory near below and above the glass transition temperature. On the other hand, the crystallinity significantly influenced the fraction of the amorphous region, where the free-volume hole exists, along with a slight change of the free-volume size. The variation of the permeability with the crystalline degree cannot be explained from the averaged free-volume fraction estimated by the whole volume of the polymer, but the permeability correlated with the free-volume size apparently. |
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