Rheological properties of montmorillonite dispersions in dilute NaCl concentration investigated by ultrasonic spinning rheometry

Abstract

Rheological changes of gelled montmorillonite dispersions with different NaCl concentrations and alkali conditions were evaluated by ultrasonic spinning rheometry. It uses velocity-profile information that is obtained in an opencylindrical container under periodic oscillations. The measurement was conducted with a focus on the rheological behavior at a low shear rate O(1 s −1), which is difficult to measure because of shear banding. The rheometry represents the coexistence of gel and sol conditions in dispersions as profiles of the phase lag of oscillations that are propagated from the cylinder wall. The critical shear rate at a yielding point and the onset of shear-thinning behavior was quantified, which has been regarded as only an apparent or speculated value by many previous researchers. Viscoelasticity from particle networks in the dispersion was observed, and the networks deform like a spring, without breaking the structure under low-shear-rate conditions.

Overview of Ultrasonic Spinning Rheometry: Application to Complex Fluids

“…The results of clay dispersion are shown in gray plots and its thixotropy is caused by the interaction between dispersed particles. 15,17) The µ drastically changes at the interface of gel and sol, where the interface is indicated as star shaped plot and determined by the phase lag profile. 18) The spatial evaluation mentioned above is an emphasized advantage of USR in comparison with standard rheometer which often shows heterogeneity due to shear history effect.…”

“…The macro-rheology in clay dispersion with both gel and sol are also discussed. 15) As the property is approximated as locally effective Newtonian viscosity, USR Ver. 1.0 still has room to explore the scope for improvement.…”

A method for evaluating time‐resolved rheological functionalities of fluid foods

“…The efficacy of USR has been verified by comparing with a standard torque‐type rheometer (Ohie, Yoshida, Tasaka, & Murai, 2022; Yoshida, Tasaka, & Murai, 2019a). USR has been used to investigate milli‐bubble/solid particle suspensions (Sakurai et al, 2013; Tasaka et al, 2015; Yoshida, Tasaka, & Murai, 2019b), an oil–water mixture (Ohie, Yoshida, Park, Tasaka, & Murai, 2020), porridge (Tasaka et al 2021), and gel–sol coexistent fluids (Yoshida, Tasaka, & Fischer, 2019; Yoshida, Tasaka, & Murai, 2017; Yoshida, Tasaka, Tanaka, Park, & Murai, 2018). In addition to its applicability to the analysis of complex fluids, USR can be used to evaluate the shear‐rate‐dependent viscosity as the shear rate is ∼ (10 1 s −1 ) near the cylindrical wall of the vessel and ∼ (10 −1 s −1 ) near the central axis, which fall in the shear rate range required for evaluating the rheological properties of swallowed foods (Kumagai et al, 2009; Shama & Sherman, 1973; Tashiro et al, 2010).…”

Nonintrusive In-Line Rheometry Using Ultrasonic Velocity Profiling

“…Depending on the specific rheological model used, USR can evaluate the effective viscosity, shear rate-dependent viscosity, and effective viscoelasticity. USR can be applied to a wide range of fluids, such as polymer solutions, , bubble suspensions, , particle suspensions in non-Newtonian fluids, clay dispersions, , and pectin gels. , We evaluated the efficacy and measurable range of USR for different materials by comparison with a standard torque-type rheometer . Some of the advantages of USR include its applicability for multiphase and heterogeneous fluids and for evaluating the transient behavior of the fluids such as thixotropy and chemical reactions.…”