Rheological Characterization of Yield-Stress Fluids with Brookfield Viscometer

Abstract

This paper analyzes various techniques to use viscometers equipped with vane spindles to characterize rheological properties of yield stress fluids. Specifically, application of Brookfield viscometers to this end is discussed. A wide selection of toothpastes and lotions were tested. It is shown that a simple method based on apparent shear rate and stress, commonly referred to as a representative viscosity method, works well for moderately non-Newtonian samples but may significantly underestimate viscosity for samples with a more pronounced yield stress behavior. To get more accurate data an integral equation relating torque to angular velocity needs to be solved which can be easily done numerically to get a good agreement between the data collected on an inexpensive viscometer and the data from high-end rheometers.

The Optimal Diameter of the Droplets of a High-Viscosity Liquid Containing Solid State Catalyst Particles

“…A Brookfield DV-II + Pro sp. 02 rotational viscometer made by AMTEK [19] was used to measure the dynamic viscosity of the liquid. Brookfield viscometers are widely used for measuring the viscosity of food and cosmetics.…”

Visual assessment and rheological characterization of shape retention of products on a surface

“…The advantage of the second method is that it provides a more comprehensive characterization of the material. The flow curve is typically fitted with an equation such as Herschel and Bulkley (1926) or Casson (1959), with a fitting parameter to be used for predicting various processes including shape retention (Potanin & Marron, 2021). In this work, we analyzed how this method can be used.…”

“…Here, we followed the default TA Instruments settings for this geometry, that is, performing a single‐point conversion of the measured variable into the apparent ones with a shift factor accounting for the gap width rather than calculating the actual shear rate and strain. The latter can be done by fitting the full flow curves (see, e.g., Ahuja et al, 2018, or Potanin & Marron, 2021) but would be largely redundant for this work, namely, to establish a correlation to sensorial attributes, in this case‐ shape retention. Thus, all rheological variables reported below are in fact apparent ones as reported by the rheometer software.…”

“…When it comes to rheological tests, preferences in the industry are often given to strain‐controlled inexpensive viscometers rather than more advanced rheometers. In our previous work, we have shown how such viscometers can be used to characterize yield‐stress materials, such as toothpaste and lotions (Potanin & Marron, 2021). This explains the focus of this work on the tests which can be performed on such viscometers along with well‐known tests performed on rheometers in stress‐controlled mode.…”

Importancia de la medición de la Viscosidad sanguínea: retos y limitaciones

“…Este viscosímetro tiene parámetros de confiabilidad muy altos, su precisión es de +/-1 %, puede evaluar viscosidades en rangos de 0.2 a 3000cP, y su uso ha sido demostrado en otros estudios en salud que evaluaban viscosidad sanguínea, cumpliendo con las recomendaciones de las guías internacionales. [25,26,32] Para evaluar los valores dinámicos de la viscosidad, se ha propuesto el uso de rotaciones diferenciadas para calcular la viscosidad sanguínea diastólica y sistólica. [33] Aunque la propuesta original fue emplear 1 y 300 sec-1 como share rate (velocidad de corte), para ello se requiere un ajuste de las revoluciones por minuto (RPM) y su normalización según el share rate del spindle (cono-plato) que se emplea.…”