Influence of particle shape and sample preparation on shear thickening behavior of precipitated calcium carbonate suspensions

Abstract To more closely bridge the technological advent of shear thickening fluids with material applications, a well-defined sample preparation protocol is needed. In this work, preparation conditions have been studied for suspensions of precipitated calcium carbonate (PCC) particles by means of a 2 k Factorial Experimental Design (DOE), with three center points, and as a function of PCC particle shape. Shear thickening maximum viscosity was the response variable and the corresponding analyzed factors were: particle concentration, stirring time, stirring speed and sonication time. Samples with rosette PCC particles exhibited a stronger shear thickening behavior in view of stronger frictional interactions and they also shear thicken at lower shear rates compared to samples with acicular PCC particles. In the case of acicular PCC particles, the shear thickening fluid that provided the highest maximum viscosity η m was obtained with higher particle concentration, lower stirring speed and shorter sonication time, as acicular PCC particles align more easily in the flow direction. In the case of rosette PCC particles, η m was achieved with higher particle concentration, longer stirring time and shorter sonication time. Finding optimal sample preparation conditions and particle shapes that take the most advantage of shear thickening behavior is very important for final applications.