Glassy State and Glass Transition-Its Elucidation and New Applications. II. Correlation Between Free Volume Evaluated from Positron Annihilation Lifetime and Gas Diffusion Coefficient of Glassy Polymers.

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  • TANAKA Kazuhiro
    Department of Advanced Materials Science and Engineering, Faculty of Engineering, Yamaguchi University
  • ITO Masamichi
    Department of Advanced Materials Science and Engineering, Faculty of Engineering, Yamaguchi University
  • KITA Hidetoshi
    Department of Advanced Materials Science and Engineering, Faculty of Engineering, Yamaguchi University
  • OKAMOTO Ken-ichi
    Department of Advanced Materials Science and Engineering, Faculty of Engineering, Yamaguchi University
  • ITO Yasuo
    Research Center for Nuclear Science and Technology, The University of Tokyo

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Other Title
  • ガラス状態とガラス転移―その解明と応用への新展開　ＩＩ　陽電子消滅寿命から評価したガラス状高分子膜の自由体積と気体の拡散係数との相関
  • ヨウデンシ ショウメツ ジュミョウ カラ ヒョウカシタ ガラスジョウ コウブン

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Abstract

Diffusion coefficients D for CO2 and CH4 as well as lifetime τ3 and intensity I3 of ortho-positronium (o-Ps) were measured for five polymers at temperatures T from glass transition temperature Tg down to Tg-150 K. There was a fairly good correlation between τ3 and log (D/T) in the temperature range above Tg-90 K. Assuming exponential distribution of the size of free volume holes in the glassy state, a mean size of the free volume holes (vh) was evaluated from τ3 by using a method previously applied for rubbery polymers. There was a good correlation between log (D/T) and 1/<vh> for these glassy polymers and the previously investigated rubbery polymers, indicating that a free volume model for diffusion is applicable in the glassy state at temperatures not much below Tg as well as in the rubbery state. Even in the glassy state, generation, and dissipation of the free volume holes with smaller sizes might occur rapidly in concert with local motion of polymer chains and side groups. This rapid generation/dissipation process enables penetrants in glassy polymers to have frequent chances of diffusion jump, as is the case in the rubbery state.

Journal

  • KOBUNSHI RONBUNSHU

    KOBUNSHI RONBUNSHU 53 (12), 834-841, 1996

    The Society of Polymer Science, Japan

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