Phenomenological Modelling of Non-Monotonous Shear Viscosity Functions

Phenomenological Modelling of Non-Monotonous Shear Viscosity Functions

Blog Article

The aim of this paper is to present a new phenomenological rheological model suitable for the description of a wide class of viscoelastic fluids.Classical phenomenological models predict the relation shear viscosity vs.shear rate (or shear stress) for shear-thinning (or thickening) materials exhibiting smooth monotonous passage from the first - upper (lower) - Newtonian plateau to the second - lower (upper) - one.However, present state of non-Newtonian materials used in practice (ranging from aqueous surfactant solutions, bituminous materials, associative polymers, polymer Rugby - Shoes - Mens thickeners, lacquers and gels, to some special disperse systems, etc.

) evokes the need to describe this - for many materials non-monotonous - relation in the corresponding way, i.e.through the sufficiently simple phenomenological model with a moderate number of parameters.A six-parameter model enabling description of not only monotonous but also non-monotonous course of shear viscosity function against shear rate (stress) is proposed including physical characterisation of the parameters.

This model describes not only extreme points (maximum or minimum) but also a possible appearance of intermediate Newtonian plateau or its indication.The meaning and influence of the individual six parameters is documented on the experimental Dish Detergent data published in the literature.There is a good agreement of the model proposed with many different experimental data representing different rheological behaviour.The applicability of this model for a wide class of viscoelastic materials is its principal advantage over the hitherto published phenomenological models.