Abstract
Dilatant behavior of slurries formed by cosmetic powders was analyzed by the rhelogical analysis. The slurry formed by sericite shows dilatant flow at large strain range. In case of sericite slurry, the storage modulus was larger than the loss modulus even when the strain of one hundred percent was added. Flowability depending on the thickness of synthetic micas tended to show dilatant behavior.
The reason why the cosmetic slurries showed dilatant behavior was considered that the affinity between these powders in a solution was weaker than the one between ordinal mica powders. The weak affinity of sericite and synthetic micas brought viscoelastic characters. Consequently, it was considered that they could not be easily molded. To get rid of the difficulty in molding, surface treatment of powder were found to be effective. When the surface of sericite was thickly coated by silicone, reduction of the dilatancy was the most significant.
