COMPARING RHEOMETER & VISCOMETER
A rheometer offers much more flexibility to provide insight into your product properties
A viscometer is well suited as a basic screening and QC tool - simple to use and relatively inexpensive to purchase, maintain and operate to provide viscosity data with relatively limited experimental options to provide limited rheological insight.
In contrast, a rheometer with rotational and oscillational capability is a versatile R&D problem solving instrument to perform an array of assays with relatively a small volume (typically100uL to 1mL/assay) to probe a broad range of rheological responses to applied forces and conditions such as stress, strain, shear, temperature, amplitude, frequency, tribology (friction), vertical compression/pull-away and surface tension. These properties include, but are not limited to viscosity, viscoelasticity, shear-thinning/thickening, flow such as pumpability, spreadability, suspension stability, texture/sensory, thixotropy, structural characterization, stringiness, stickiness, adhesion/cohesion, and physical and thermal stability.
The above tabs describe in more detail just some of the primary rheology measurements and their applications that RTS offers to help you better understand your product properties. RTS is highly streamlined regarding client interactions (i.e. no bureaucracy), is very flexible and often performs investigative one-off analyses with rapid turn-around that includes a detailed report and follow-up discussions to meet your particular rheological needs. Assays are performed with the very capable and flexible Kinexus Pro rheometer.
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Figure 1 highlights an important potential oversight when using a viscometer to determine viscosity at a single shear rate instead of a rheometer measuring across many shear rates. This classic example, using a rheometer shows mayonnaise (black curve) being more viscous than honey (gold curve) at lower shear rates (<14/sec), both having same viscosity at 14/sec, and then become less viscous than honey at >14/sec due to shear thinning. The decreasing viscosity with increasing shear rate shows the shear thinning mayonnaise to be "non-Newtonian". In contrast, honey maintaining a constant viscosity is "Newtonian". The extent and rate of a shear thinned sample to rheologically rebuild can be quantified with a "Thixotropy" assay.
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