![]() ![]() Only true Newtonian solutions are independent of the amount of shear applied. Thus when you use a viscometer you cannot compare formulations at different spindle/speeds or even the same formulation at a different spindles/speeds during a stability trial as you are applying different amounts of shear. The issue is every spindle and speed combination produces a different amount of shear to the cream and as a result you are on different parts of a thixotropic curve (see Fig 1). While simple Newtonian fluids can be characterised by a single value of viscosity, most creams we deal with daily change their viscosity with changing shear – they are described as Thixotropic. Rheology is the more complex study of the flow of liquids, gels, creams or ointments that exhibit some level of flow.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |