Inverse thixotropy

Inverse thixotropy (or negative thixotropy) is the opposite of thixotropy. Such substances show a steadily increasing apparent viscosity when sheared at a constant rate. Examples are rare, one being suspensions of vanadium oxide. 

PROPERTIES OF SPECIAL INTEREST Weak acid, brittle solid that cannot be molded, crosslink on heating, decomposes without softening at high temperature, too water sensitive to be plastics, generation of viscosity and thixotropy at low concentrations, interaction with counter-ions or charged particulate matter, inverse solubility-temperature behavior. 

Rheopexy n. (1) The inverse of thixotropy. The viscosity of a rheopectic material increases with time under an applied constant stress, approaching a constant value. When the stress is removed or reduced, the viscosity diminishes toward its original value. (2) A special form of thixotropic gel, which possesses the property of solidifying more rapidly when sheared (stirred) very slowly than when at complete rest. It should not be confused with dilatancy. The equilibrium state of the former is a sohd gel, while the latter is a hquid. 

Kawashima Y, Hino T, Takeushi H, Niwa T, Horibe K. 1991. Rheological study of W/ OAV emulsion by a cone-and-plate viscometer Negative thixotropy and shear-induced phase inversion. Int J Pharm 72 65-77. 

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