Most fluids are non-Newtonian. What that means is that as the sample is exposed to shear rates, the viscosity can change (increase or decrease). Some samples display Newtonian behavior until a certain shear rate point where it changes the viscosity so it's imperative to be aware of all possibilities and expand your testing capabilities as wide as possible so you are prepared for all unknown.
When measuring non-Newtonian samples on rheometers and viscometers, such solutions often violate the assumptions programmed into the instrumentation. Diving deeper, the assumption that the change in shear stress over shear rate is linear would then be violated. However, there is a way to work with non-Newtonian samples in such cases by using the Weissenberg-Rabinowitsch-Mooney Correction (WRM).
In this webinar, we will go over the mathematics of the WRM correction through a step by step tutorial on how to deal with non-Newtonian samples in such cases and specifically for use with RheoSense viscometers powered by VROC® technology (listed in USP as chapter 914, Rectangular slit method).