Dilatant behavior is often observed in highly concentrated suspensions where particles become increasingly crowded during rapid deformation.

As the shear rate increases, the particles may lose their ability to move past each other efficiently, resulting in an increase in apparent viscosity.

Cosmetic Relevance

Dilatant behavior is less common than shear-thinning behavior in conventional creams and lotions but can be relevant to highly concentrated dispersions, mineral systems and specialty products.

It can affect pumping, filling and mixing behavior.

Processing Considerations

A formulation exhibiting strong shear thickening may become unexpectedly difficult to pump or mix at high processing speeds.

This is one reason rheological characterization should be performed under conditions that approximate actual manufacturing.

References

Barnes, H. A. A Handbook of Elementary Rheology.

Barel, A. O., Paye, M. and Maibach, H. I. Handbook of Cosmetic Science and Technology.

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