We propose a practical map representation termed rheology mapping for comprehensively evaluating the dependence of viscoelasticity on applied shear deformation and shear timescale represented by oscillation frequency, utilizing ultrasonic spinning rheometry (USR), which has excellent applicability to a wide variety of polymer solutions. The rheology mapping was applied to two typical kinds of polymer solutions. One is carboxymethyl cellulose (CMC) aqueous solution, a well-known viscous and shear thinning fluid. The other is polyacrylamide (PAM) aqueous solution generally considered as a viscoelastic fluid while its viscoelasticity is difficult to be evaluated by a standard torque-type rheometer. The rheology mapping for the solutions showed notable rheological properties. The viscoelasticity of both the CMC and PAM solutions vary widely from elastic to viscous, depending on the applied shear rate, strain, and oscillation frequency. The mapping also revealed the clear dependence of the viscosity of the solutions: the CMC solutions on the shear rate and the PAM solutions on the shear strain. These results provide quantitative support of findings in other reports associating these macroscopic properties with the microscopic dynamics of polymer coils.

This paper evaluated measurement accuracy and precision of ultrasonic spinning rheometry (USR), which can evaluate rheological properties through equation of motion and velocity information captured by ultrasonic velocity profiler (UVP), in cases that assumptions of two-dimensional one-directional flow are not perfectly satisfied. Time variation of effective viscosity in separating oil-water mixture was examined by USR to demonstrate its applicability for both time-dependent rheological properties and multiphase media, which cannot be evaluated by conventional torque-type rheometers. Decrease in pseudoplasticity and effective viscosity of the media with time during separation of water droplets from the media accompanied by monotonic decrease in diameter and volume fraction of the droplets on the measurement line, was quantified. The time variations show the same trend with formula theoretically derived for evaluating emulsion viscosity, but the viscosity was estimated larger than the theory. An increase of effective volume fraction or non-equilibrium flow field may have increased the viscosity.

A novel method enabling in situ measurement in a reserve tank for evaluating an instantaneous viscosity curve is presented. This aims to satisfy the practical demand of industrial production process for monitoring real-time rheological properties without taking samples. With applicable ranges of shear rate and viscosity, O(10 −1 −10 2 s −1 ) and O(10 −2 −10 0 Pa•s), it enables evaluation of fluid properties having shear strain rate dependence, based on ultrasonic spinning rheometry. Since this method evaluates the characteristic of shear thinning viscosity while changing the fluid temperature in a reserve tank, some useful examples are expected as further applications for measuring viscosity during chemical reaction processes, such as gelation, hydrolysis, and polymerization. Efficacy of the method evaluating rheological properties is validated by numerical and experimental results.

A novel rheometry termed ultrasonic spinning rheometry (USR) is overviewed in this paper. This methodology utilizes ultrasonic velocity profiling as a representative velocimetry for various complex fluids including multi-phase state. The USR determines optimal properties from cost function which is calculated from both equation of motion and constitutive equation of test fluids by substituting the measured velocity profiles. Various examples are explained to indicate the applicability and efficacy of USR for measuring complex fluids; silicon oil, polymer solution, clay dispersion, water-oil two-phase fluid, and more. Through these results, we discussed future prospects of USR developments regarding its applicability and efficacy.

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