Extensional viscosity is a critical parameter for characterizing fluids, such as paints, coatings, and inks, that experience extensional deformation during manufacturing, processing, or application. Extensional rheological measurements were once obtained with the beloved Caber extensional viscometer, which has since been discontinued.

Now, the m-VROC II viscometer can guide you to precise data, supporting formulation, quality control, and process optimization in these and other applications.

The m-VROC II viscometer measures extensional viscosity using a small sample volume (<1.5 mL) and offers a wide dynamic range under precise temperature control.

We tested an off-the-shelf paint across a wide range of extensional rates at a controlled temperature of 25 °C. The test was conducted as follows:

• Two chips were used for testing: EB20 and EE20 extensional chips.

• For the EB20, ~100 μL of sample was loaded into the syringe. For the EE20 chip, ~1.5 mL of sample was front-loaded into a 2.5 mL syringe.

• Extensional viscosity data was gathered across a broad range of extensional rates using the software’s automatic measurement features. The software selects the appropriate rates, so even if you’re unsure, you can run tests like an expert.

• The cleaning solvent order on CCS includes 2.5 % Aquet, DI water, and Acetone.

The paint exhibits non-Newtonian extensional thinning behavior, with viscosity decreasing from ~270 Pa-s to 4 Pa-s as the extensional rate increases from 0.9 s⁻¹ to 14,000 s⁻¹. The data demonstrates high measurement repeatability, showcasing the ability to obtain accurate and precise results without requiring extensive expertise. Paints, coatings, and thick samples can be challenging to work with in general but can be run seamlessly using the m-VROC II viscometer.