Measurements of Diffusion Constants by the Moiré Method

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  • OKABE Masaru
    Department of Chemical Process Engineering, Faculty of Engineering, Ikutoku Technical University
  • SHIBUYA Kaoru
    Department of Chemical Process Engineering, Faculty of Engineering, Ikutoku Technical University
  • MATSUDA Hideomi
    Department of Chemical Engineering, Faculty of Textile Science, Shinshu University

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Other Title
  • モアレ法による拡散定数の測定
  • モアレホウ ニヨル カクサン テイスウ ノ ソクテイ

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Abstract

In order to precisely obtain the diffusion constants in dilute polymer solution, a diffusion apparatus with moire optics which is much simpler than the Schlieren optics was designed and constructed. According to the previous procedures, a sharp boundary between solution and solvent is formed in the middle of the cell. The cell is placed between two identical glass-made grids on which equispaced parallel lines are notched with 0.254mm spacing. When the laser beam illuminates the first grid (G1), the equispaced parallel lines are displaced behind the cell because of bending of the light caused by the refractive index gradient within the cell. If the image of G1 is superposed on the second grid (G2) which is beveled with an angle θ to the horizontal G1, the moiré patter n is formed on G2. The diffusion constants measured by the present method are in good agreement with the reported values within experimental errors. According to the present method, as the scale of abscissa of diffusion curve is directly determined by the spacing of G2 lines, the diffusion constants are more precisely measured than the conventional methods.

Journal

  • KOBUNSHI RONBUNSHU

    KOBUNSHI RONBUNSHU 38 (1), 15-21, 1981

    The Society of Polymer Science, Japan

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