As the user of a modern rheometer you have many different measuring systems available for use.
You can rheologically characterize almost all substances.
But what are the criteria for choosing the correct measuring system?
To select the best measuring system for your sample, consider the following:
- What is the samples' consistency? Where is the sample located on the Rheology Road?
- Are there particles in the sample and how big are they?
- How much sample is available for the measurement?
- How difficult is the cleaning?
- Does the sample sediment or dry out?
- What are the benefits and drawbacks of the different systems?
What is the Samples' Consistency? Where is the Sample Located on the Rheology Road?
Table 1 gives an overview and rough classification of different substances, from low-viscosity liquids to solids. Each column lists the most common test types and a recommended measuring system.
The lower the viscosity of a sample, the larger the surface of the measuring bob should be.
Low-viscosity samples are often measured in cylinder measuring systems. At high shear rates the centrifugal forces lead to turbulence in the measuring gap (Taylor vortices). This leads to an apparent increase in the viscosity. Therefore, a critical shear rate limit should not be exceeded.
My recommendation: The more viscous the substance, the more likely it is that a cone-plate or parallel plate measuring system should be used.
Table 1. Rheology Road (DG: double-gap measuring system, CC: cylinder measuring system, CP: cone-plate measuring system, PP: parallel plate measuring system, SRF: Solid Rectangular Fixture, UXF and SER: Extensional Rheometer Systems).
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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.