RHEO-OPTICS OF CONCENTRATED KAOLINITE SUSPENSIONS

A shear-optical method is described which uses multiply scattered ligh t to investigate concentrated colloidal kaolinite suspensions. The she ar-optical response derives from the orientation of flee fragments or discrete colloidal particles in the flowing suspension. The apparatus required is robust and inexpensive. The method is used to study the ef fect of pH, and an organic deflocculant, on the flocculation of kaolin ite. The effect of pH on the shear-optical response of concentrated su spensions correlates inversely with the pH-dependence of the fractal d imension measured by Herrington and Midmore for kaolinite flocs in ver y dilute suspensions. The effect of deflocculant on the shear-optical response correlates closely with the effect of the same deflocculant o n the suspension viscosity.