Fumed Silica-Based Suspensions for Shear Thickening Applications: A Full-Scale Rheological Study

Abstract

Understanding shear thickening fluids (STFs) is critically important in a broad spectrum of fields ranging from biology to military. STFs are referred to the suspension of solid particles in an inert carrier liquid. Customizing the thickening behavior is vital for obtaining desired properties. Hence, comprehending shear thickening mechanisms is necessary to fully understand the factors affecting the shear thickening response of the STFs. Herein, we systematically investigate the effects of a wide range of parameters, from inherent properties of the constituents, including size and surface chemistry of the suspended particles, to practical conditions such as temperature and shear history, on the shear thickening behavior of fumed silica nanoparticles (NPs)-based suspensions in a polyethylene glycol (PEG) medium. Accordingly, increasing the hydrophobicity of the silica NPs or decreasing the NP size transforms the suspensions from sol to gel. The sol systems exhibit a strong shear thickening response, while shear thinning behavior is prominent in the strong gel systems. Hybridization of different silica NPs is also leveraged to tune the shear thickening behavior. In addition, we showcase the decisive role of operating temperature or shear history on the shear thickening behavior of suspensions. For instance, in terms of the shear history, above a critical value of preshear, the shear thickening behavior occurs at lower shear rates for STFs containing hydrophilic NPs. It is believed that the provided insights in this study can pave the way for developing advanced STFs with prescribed features.

A solution-processable and highly flexible conductor of a fluoroelastomer FKM and carbon nanotubes with tuned electrical conductivity and mechanical performance

“…The mixing efficiency depends on shear-induced diffusion, flow properties (viscosity), mixing time, mixing speed, the aspect ratio of CNTs, CNT concentration, and the transient rheological properties of the suspension. [35][36][37] The mixing performance is evaluated based on these parameters and the final electrical, mechanical, and rheological properties.…”

Mechanisms of microstructural deformation governing Vickers hardness in phase‐separated calcium aluminosilicate glasses

“…In the case of silica particles suspended in a low-viscosity fluid, particle collision often results in flocculation. 24,25 This process is responsible for many particle suspensions displaying shear thickening at high particle concentrations. If the particle viscosity is low, or if there is some reaction between the particles, particle collision may result in gelation.…”

“…Particle collisions in a suspension can have a profound impact on its properties. In the case of silica particles suspended in a low‐viscosity fluid, particle collision often results in flocculation 24,25 . This process is responsible for many particle suspensions displaying shear thickening at high particle concentrations.…”

Research on rheological properties and phenomenological theory-based constitutive model of magnetorheological shear thickening fluids

“…STF has become a popular intelligent material with broad application prospects in fields such as military, sports, construction, and biomedical engineering. In recent years, numerous scholars have been committed to studying various factors (such as particle size, suspension concentration, surfactants, temperature, etc) that affect the shear thickening rheological behavior of STF, and these studies have led to significant advances in the shear thickening performance and variable damping characteristics of STF [3][4][5][6][7][8][9][10][11]. Galindo-Rosales et al [3] discovered that the shear thickening behavior of STF is not a continuous process, but a staged change, which can be divided into three distinct stages.…”