The effects of some polyelectrolyte chemical compositions on the rheological behaviour of kaolin suspensions

Many ceramic materials are factory-made via ceramic suspensions. The rheology of these suspensions must be appropriate and their solid content must be as high as possible in order to minimize the drying cost. Currently, the addition of minor quantities of polyelectrolyte in the classical deflocculating mixture of sodium silicate and sodium tripolyphosphate has become useful to this effect. The present paper discusses a rheological test established to put the rheological behaviour of these suspensions in parametric form. These parameters cover different rheological aspects: equilibrium, kinetics (thixotropy) and structural elasticity. Different polyelectrolytes in different percentages were tested for their power to deflocculate different kaolin suspensions. The deflocculating power of these polyelectrolytes was then correlated with their chemical composition.