“What is the difference between newtonian viscosities and thixotropic viscosities? How would that impact my application?”

Newtonian products are materials which have the same viscosity even under different shear rates. Water, milk, and mineral oil are examples of common newtonian materials. Thixotropic materials on the other hand will flow when a shear force is put onto the material (like squeezing a tube of toothpaste), but when the force is removed, the material will not flow. A newtonian material might be used to pot an application or fill a cavity, while a thixotropic adhesive might be used to dispense a bead along a molded ridge.

Adhesives adhesive viscosity, newtonian, thixotropic, Viscosity

A question that came through:

“We currently use one of your medical-grade adhesives with a viscosity of 500 cP. We are looking for a higher-viscosity adhesive and do not want to have to redo biocompatibility testing. Can you tell me if you have an adhesive that is made of the same materials as the one we now use but with a higher viscosity?”

Answer:

DYMAX offers adhesives with several viscosity variations. An adhesive might have a standard base viscosity of 500 cP but also be available in a T (thick) grade with a viscosity of approximately 5,000 cP, a VT (very thick) grade with a viscosity of approximately 12,500 cP, and a gel grade with a viscosity of approximately 25,000 cP. These thixotropic versions all use a nonreactive biocompatible thickener and exhibit the same biocompatibility test results as the standard product. The thixotropic adhesives with gel viscosity allow the material to have a little slump, a minor slump, or no slump at all, enabling them to be dispensed along a ridge or in a groove.

View our Viscosity Comparison Chart.

Adhesives, Medical Adhesives, Medical-Grade, Viscosity