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Rotational Viscosity

Viscosity:- A measure of the resistance of a liquid to flow.

Thixotropic:- Describes materials that are gel-like at rest but liquid when agitated.

Centipoise:- A unit of measurement of which water is the standard at 1cP.

Newtonian Liquids:- The viscosity of a Newtonian liquid is dependent only on temperature, not shear rate and time.

Non-Newtonian Liquids:- Time-dependent. The viscosity of the liquid is dependent on temperature, shear rate and time.

Depending on how viscosity changes with time the flow behavior is characterized as;
<> Thixotropic (time thinning, i.e. viscosity decreases with time).
<> Rheopetic (time thickening, i.e. viscosity increases with time).
Thixotropic liquids are quite common in the chemical and food industries. Rheopectic liquids are very rare.
Note: Some liquids show time thinning behavior due to breakdown of structure. This phenomenon is sometimes known as Rheomaiaxis.

Non-Newtonian Liquids:- Time-independent. The viscosity of a Non-Newtonian time-independent liquid is dependent not only on temperature but also on shear rate.

Depending on how viscosity changes with shear rate, the flow behavior is characterized as;
<> shear thinning - also known as Pseudoplastics - the viscosity decreases with increased shear rate.
<> shear thickening - also known as Dilatant - the viscosity increases with increased shear rate.
<> plastic - exhibits a so-called yield value, i.e. a certain shear stress must be applied before flow occurs.

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Rotational Viscosity