Rheometers: How and What do they Measure?

To understand rheological measurements it is often helpful to learn more about the rheometer setup and how it works.

To measure the rheological properties of your sample with a rotational and oscillatory rheometer requires determination of the torque and deflection angle of the measuring bob. Your sample provides resistance or a reset torque to the setting. The resulting deflection angle is then measured by the rheometer's encoder. The speed is calculated from the deflection angle and the time.

However, as the user you are usually more interested in the rheological parameters. How do you get these? Rheological parameters are calculated from the measured values torque, deflection angle and speed using conversion factors (see Table 1). All further parameters, such as viscosity, are not measured but calculated.

Table 1. Measuring values and rheological parameters with the conversion factors.

Measurement values Conversion factor Rheological parameter
Torque M [mNm] CSS factor Shear stress τ [Pa]
Deflection angle φ [µrad] CSD factor Deformation γ [%]
Speed n [min-1] CSR factor Shear rate ImageForArticle_18927_15808893341096910.png[s-1]

 

Rheometer Design

Rotational and oscillatory rheometers are set up as shown in Figure 1. The measuring head contains the drive motor and encoder which measure and set the torque, deflection angle and speed.

Setup of a modern air-bearing rotational and oscillatory rheometer with the most important components.

Figure 1. Setup of a modern air-bearing rotational and oscillatory rheometer with the most important components

Want to know more? Click here to read the full article.

This information has been sourced, reviewed and adapted from materials provided by Anton Paar GmbH.

For more information on this source, please visit Anton Paar GmbH.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Anton Paar GmbH. (2020, February 14). Rheometers: How and What do they Measure?. AZoM. Retrieved on August 09, 2020 from https://www.azom.com/article.aspx?ArticleID=18927.

  • MLA

    Anton Paar GmbH. "Rheometers: How and What do they Measure?". AZoM. 09 August 2020. <https://www.azom.com/article.aspx?ArticleID=18927>.

  • Chicago

    Anton Paar GmbH. "Rheometers: How and What do they Measure?". AZoM. https://www.azom.com/article.aspx?ArticleID=18927. (accessed August 09, 2020).

  • Harvard

    Anton Paar GmbH. 2020. Rheometers: How and What do they Measure?. AZoM, viewed 09 August 2020, https://www.azom.com/article.aspx?ArticleID=18927.

Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit