Ceramics-Silikáty 17, (1) 9 - 20 (1973) |
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THE EFFECT OF PARTICLE SIZE DISTRIBUTION ON APPARENT VISCOSITY OF A DISPERSION SYSTEM
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Škvára František, Vančurová Miroslava |
Joint Laboratory for Chemistry and Technology of Silicates, Czechoslovak Academy of Sciences and Institute of Chemical Technology, Prague
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Theoretical assumptions on the effect of particle size distribution on apparent viscosity of the system were verified experimentally by measuring the viscosity of polymethyl methacrylate microbeads in glycerine-ethanol mixture and that of ground gypsum in water at various proportions of two or three monodispersional fractions, and at various total concentrations. In terms of proportions of the two particle size fractions, viscosity of a bimodal system exhibits a sharp minimum at otherwise equal total concentration. The effect in question is becoming more pronounced at increasing concentrations. The reduction of viscosity is still more marked with systems comprising three particle size fractions. The course of viscosity vs. composition and the viscosity minimum position established experimentally were in good agreement with the values computed. Mixing of more than three particle size fractions was shown to bring about no substantial decrease in viscosity. The findings can be utilized practically for improving the workability of suspensions, above all mortars, plasters, etc. |
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