Butterfly Light Scattering Pattern and Rheology of a Sheared Thixotropic Clay Gel

The behavior of a thixotropic clay gel under shear flow, is studied by combining a static light scattering technique and rheometric measurements. In the rest state, the gel structure is composed of micrometer-sized aggregates associated as a fractal mass. Under steady shear, a butterfly-type light scattering pattern is observed. This can be related to a contraction and a stretching of the micrometer-sized aggregates, perpendicularly to the shear direction. The influence of the shear rate on the disaggregation process is also studied and correlated to rheometric measurements.