CHALLENGES IN CHARACTERIZATION OF CONCENTRATED SUSPENSIONS

With a decrease in particle size below 1 mu m the role of surfaces and interfacial phenomena dominates the properties of powders in liquids. A knowledge of properties of the system is often desired to develop p redictive strategies to control the state of dispersion and aggregatio n of powders. To obtain the desired stability and rheology of suspensi ons, an adjustment of both physical and chemical variables might be re quired. The success of such an approach depends on the ability to pred ict correctly the system response from characteristics of the powder a nd suspending medium. Several traditional methods of characterization depend upon measurements in dilute suspensions, whereas most applicati ons deal with processing and transport of dispersions at large particl e loading (percent solids). Challenges in relating properties measured in dilute suspensions to predict the behavior of concentrated suspens ions will be discussed. Both thermodynamic or equilibrium, and kinetic or rate effects are considered. (C) 1998 Elsevier Science B.V.