Definition of Dilatant flow from the PharmacyDictionary.in

Dilatant flow

Synonyms or meaning of Dilatant flow

A characteristic exhibited by polyphasic, liquid systems in which viscosity increases as “shearing stress” increases; for example, pharmaceutical suspensions for which “rate of shear” (velocity gradient) is plotted against “shearing stress” (force per unit area) using an appropriate viscometer.

Dilatant flow or shear thickening behavior is particularly relevant for suspensions.

Suspensions are a type of pharmaceutical dosage form where solid particles are dispersed in a liquid medium. The rheological behavior of these suspensions, including their viscosity or resistance to flow, can significantly impact their processing, stability, and performance.

Dilatant flow is characteristic of suspensions with a high concentration (typically 50% or more) of small, deflocculated particles. When these suspensions are subjected to shear stress, such as during mixing or pumping, they exhibit an increase in viscosity. This is because the particles increase in volume when sheared, leading to an increase in resistance to flow.

This behavior can have practical implications in the pharmaceutical industry. For instance, it can affect the ease of processing of the suspension, its stability under different conditions, and its behavior when administered to the patient. Therefore, understanding and controlling the rheological properties of pharmaceutical suspensions, including dilatant behavior, is crucial in pharmaceutical formulation and manufacturing.

It’s important to note that not all suspensions show dilatant behavior. The rheological behavior of a suspension can be influenced by various factors, including the size, shape, and concentration of the particles, the properties of the dispersion medium, and the presence of any additives.

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