The effects of particle size on reversible shear thickening of concentrated colloidal dispersions

Abstract

The particle size dependence of the reversible shear thickening transition in dense colloidal suspensions is explored. Five suspensions of monodisperse silica are synthesized via the Stöber synthesis. The physicochemical properties of the dispersions are quantified using transmission electron microscopy, dynamic light scattering, small angle light scattering, electrophoresis, and viscometry. Rheology measurements indicate a critical stress marking the onset of reversible shear thickening that depends on the dispersion's particle size, concentration, polydispersity, and interparticle interactions. A simplified two particle force balance between the interparticle repulsive forces and the hydrodynamic compressive forces is used to derive a scaling relationship between this critical shear stress and the suspension properties. The scaling is tested against the fully characterized silica dispersions, which span nearly a decade in particle size. Furthermore, bimodal mixtures of the dispersions are employed to evaluate the accuracy of the scaling to predict the critical shear stress for dispersions with varying degrees of polydispersity. The success of the scaling supports the hydrocluster mechanism for shear thickening and suggests methods for controlling shear thickening by tailoring particle properties.

Design and Manufacturing of a Novel Shear Thickening Fluid Composite (STFC) with Enhanced out-of-Plane Properties and Damage Suppression

“…5, which illustrates the existence of a strong relationship between volume fraction and the critical shear rate. Indeed, for higher particle concentrations, γ c moves to lower values due to the reduced intra-particles distance, anticipating the transition between thinning and thickening effects, as reported by Maranzano et al [14]. …”

“…-Increasing the concentration of particles within the fluid will lead to an enhancement of the thickening effect, therefore the weight fraction has to be evaluated according to the system viscosity requirement [14]. For our purposes the concentration required is as it gives good results in terms of impact resistance and workability for composite applications.…”

Does Shear Thickening Occur in Semisolid Metals?

“…This is the phenomenon observed with dense suspensions of cornstarch in water, which allows someone to run across the surface of the suspension in a swimming bath for example (but when they stand still they sink in). Brown et al [6] have argued that all suspensions should show shear thickening under certain conditions because the underlying mechanisms (hydrodynamics, [7,8] dilatation [9][10][11] ) are general but they demonstrate that shear thickening can be masked by a yield stress. They attribute discontinuous shear thickening to frictional particle contacts that form when dense particle arrangements begin to dilate and push against boundaries.…”

Discontinuous Shear Thickening in Cornstarch Suspensions

“…Recent works thus suggest that it is a dynamic or shear jamming transition, which motivates a considerable attention both from experiments [2], numerical simulation [3][4][5] and theory [6]. Shear thickening is also observed in dense colloidal suspension, where it has been related to the formation of dense clusters of particles [7][8][9]. In these systems, the competition between shear induced cluster formation and Brownian motion that homogenizes the suspension naturally determine a critical shear rate for the onset of shear thickening.…”