Читать книгу The Rheology Handbook - Thomas Mezger - Страница 147

After stirring, yogurt remains considerably thinner compared to the initial state, even when waiting a long period of time.

Each material displaying a certain degree of structural decomposition in the shear phase with time, of course is showing time-dependent behavior. However, such a material is not thixotropic if the initial structural strength does not completely return finally, even after an “infinitely” long period of time at rest. In this case a permanently remaining structural change has taken place. If structural regeneration does not occur completely (i. e. to 100 %), it is sometimes referred to as incomplete or “false thixotropy”. In this case, instead of thixotropy it is better to speak of partial regeneration, e. g. expressed in a percentage compared to the initial viscosity value.

Example of a meaningful specification, related to the viscosity value: After a high-shear phase, during a rest period of t = 120 s, structural regeneration has taken place up to 70 % compared to the initial structural strength-at-rest before shearing.