Rheological and Sedimentation Behaviour of Strongly Interacting Colloidal Systems

Abstract

In many industrial applications of colloidal dispersions, it is the flow properties of the system which are of paramount importance. Sometimes the flow characteristics are important in the properties of the final product (as, for example, in paint and ink preparations). In other cases, the preparation of the final product depends for its success on the proper control of flow properties of a colloidal dispersion or slurry (e.g. in paper making or ceramic casting). In rare cases, when the system consists of spherical particles, stabilised against coagulation and at fairly low concentration, the flow behaviour is Newtonian and characterised by a simple shear viscosity, η, independent of how fast the system is being sheared. More usually, colloidal dispersions are distinctly non-Newtonian and it is this non-Newtonian character which is principally responsible for the desired product characteristics. The simplest and most common type of non-Newtonian shear behaviour occurs when the viscosity depends on how strongly the system is sheared.