EFFECT OF FLOCCULATION ON THE DILATANT FLOW FOR AQUEOUS SUSPENSIONS OF TITANIUM DIOXIDES

The rheological properties were studied for suspensions of two titanium dioxide (Anatase) powders with different particle sizes dispersed in water by adding sodium pyrophosphate as the dispersing agent. Using a capillary viscometer, flow measurements were made under conditions of varying amounts of dispersing agent as well as shear histories of suspensions. The sedimentation behavior and zeta-potential were also measured as a means of studying the stability of the suspensions against flocculation. The onset of dilatancy was observed at higher shear rates and the extent of dilatancy decreased with an increase in a dispersion stability varied by the amount of dispersing agent as well as in a degree of dispersion varied by the shear history. The suspension with large particles showed dilatant behavior similar to that of the stable suspensions. Relationships between the rheological properties and the stability of suspensions against flocculation were discussed on the basis of the theory of the stability of lyophobic colloids. © 1979, The Society of Rheology. All rights reserved.