Study on the rheology of Mg-Fe-hydrotalcite-like compound/kaolinite suspensions

The rheological properties of Mg-Fe-hydrotalcite-like compound/kaolinite suspensions, such as yield stress and thixotropy, have been investigated, mainly on the effect of mass ratio of Mg-Fe-HTlc to kaolinite suspensions (R). Both of the yield stress tau(y) obtained in the Controlled Rate mode and critical shear stress tau(c) obtained in the Controlled Stress mode decreased first then increased with increase of R. In the linear oscillatory experiments, the type of thixotropy of HTlc/kaolinite suspensions was transformed from positive thixotropy to complex thixotropy with increase of R. It was the first time to find the complex thixotropy in linear viscoelastic region by oscillatory shear measurements. In the steady shear experiments, the recovery processes have been monitored at low shear rate, finding a very interesting phenomenon, i.e., the fluctuation behavior of apparent viscosity eta with t, and its disappearance when D-L and R were relatively high. The results were discussed on the basis of the interactions between the HTlc and kaolinite particles.