Silica–paraffin and kaolin–paraffin dispersions: Use of rheological and calorimetric methods to investigate the nature of their dispersed microstructure units

The yield stress and enthalpy of the wetting of silica–paraffin and kaolin–paraffin dispersions were measured as a function of the volumetric concentration θ of the dispersed colloidal powders after having performed a careful analysis of their macro–meso microstructure. The evolution and stability of the corresponding microstructure units is strongly linked to the shape of the τ0 versus θ and ΔH versus θ curves. The percolation threshold θ τ 0 * and θ Δ H * values are fairly equal for each dispersion. These values were observed to be 9% and 18% for silica–paraffin and kaolin–paraffin dispersions, respectively. Two different paths of microstructural evolution were identified for the silica–paraffin and the kaolin–paraffin dispersions with respect to particle shape and size. The stability of the silica–paraffin microstructure units was greater than that corresponding to the kaolin–paraffin ones.