The rheological properties of suspensions of spherical particles in non-Newtonian liquid

The Rheological Properties of Suspensions of Spherical Particles in Non-Newtonian Liquids. This investigation concerns the measurement of the rheological properties of suspensions of solid spherical particles in several non-Newtonian pseudo-plastic liquids. Measurements have been made at various solids concentrations from 0 to 10% by volume, and at shear rates up to 200 sec[-1]. In the course of this work new results have been obtained which show that end corrections of up to 25% are necessary in co-axial cylinder viscometry, when using pseudo-plastic liquids. In addition, observations in the co-axial cylinder system have revealed a complex migration process in which the suspended solids migrate axially along the length of the annular gap. This motion is thought to be related to the normal stresses developed in the suspending medium during shearing. It has been shown that, with suitable precautions, measurements of the rheological properties of pseudo-plastic normal stress producing liquids are practicable, and three groups of data are reported: (1) The tangential shear stresses (S) developed by the suspensions have been determined as functions of the shear rate (D) and the volumetric solids concentration (Cv) using a co-axial cylinder viscometer. It has been found empirically that the ratio (D/D[o])s is a function of Cv only for all the pseudo-plastic solutions tested; while (S/S[o)[s] is a function of Cv and the shear rate. (2) The variation of the normal stress difference (p[11]-p[12]) has been investigated as a function of solids concentration and shear rate, using a cone-plate Rheogoniometer. (3) The dependence of the "transverse viscosity" of the test solutions upon the primary shear rate has been investigated using a co-axial cylinder system with a transparent outer cylinder.