Effective volume and immobilization concentration of dispersed particles

Abstract

We report flow curves of china clay slurries measured over a wide range of concentration and shear rate, therewith calculating the hydrodynamic volume and the maximum packing fraction of particles under shear, following Mooney. Results are consistent with limiting viscosity number measurements, and show the decrease of effective volume like shear thinning behaviour. To the contrary, the concentration of immobilization decreases after a maximum towards a high shear value. This makes it conceivable that shear forces make the dispersion change from one state to another, represented by two limiting flow curves. The transition between both produces a viscosity maximum.