Rheological Parameters of Shear-Thickening Fluids Using an Experimental Design

Abstract: The influence of important factors related to fluid preparation on shear-thickening fluids (STF) is not well explored in literature. Thus, this paper aimed at analyzing the statistical significance of experimental conditions, such as fumed silica concentration (Cs), stirring time (tst), stirring speed (Sst) and sonication time (tso ), on the rheological behavior of fumed silica particles and PEG 400 dispersions. For that, a 2k factorial Experimental Design (DOE), with three center points, was accomplished. The investigated response variables were: maximum viscosity (ηm); critical shear rate ( γ ˙ m) where the viscosity is maximum; and agglomerate size of particles during preparation (R). All factors were statistically significant for all three response variables. Higher viscosity values for shear rate range analyzed was obtained with longer tst, lower Sst and longer tso. An important contribution of this paper was to show discontinuous shear thickening (DST) for lower concentrations than previously found in literature only changing the preparation protocol.