Non-linear viscoelasticity and two-step yielding in magnetorheology: a colloidal gel approach to understand the effect of particle concentration

SEGOVIA-GUTIÉRREZ, J. P. ; BERLI , CLAUDIO L. A.; DE VICENTE, J.

JOURNAL OF RHEOLOGY

JOURNAL RHEOLOGY AMER INST PHYSICS

Año: 2012 vol. 56 p. 1429 - 1448

0148-6055

The yielding behavior of conventional magnetorheological (MR) fluids is revisited for a wide range of magnetic fields and particle concentrations under a colloidal gel perspective. A two-step yielding behavior is found at intermediate magnetic fields (10 kA/m) that can be explained as a transition from a strong-link to a weak-link (or transition) regime upon increasing the particle concentration in the MR fluid. This two-step yielding behavior is reminiscent of the classical concepts of static (frictional) and dynamic (Bingham) yield stress. By relating macroscopic elastic properties to a scaling fractal model we could identify the prevalent gelation regime in MR fluids.