CONTROL OF STABILITY FLOCCULATION AND RHEOLOGY OF CONCENTRATED SUSPENSIONS

The various interaction forces that govern the stability/flocculation of concentrated suspensions are briefly described. Combination of these interactions result in three main energy-distance curves which determine the final state of the suspension. This ranges from colloidally stable to strongly flocculated (coagulated) suspensions. A schematic representation of the various states of suspensions is given. These states are reflected in the rheology of the suspension which can be investigated using steady state, constant stress (creep) or oscillatory measurements. Examples are given to illustrate the rheology of various systems: (i) those based on hard sphere interaction; (ii) those based on double layer repulsion; (iii) sterically stabilised systems; (iv) flocculated systems either weakly or strongly.