Nonlinear rheology of Laponite suspensions under an external drive
نویسندگان
چکیده
We investigate the nonlinear rheological behavior of colloidal suspensions of Laponite, a synthetic clay, driven by steady homogeneous shear strain. We show that the external drive leads to drastic slowing down of the aging dynamics or even, in some cases, in rejuvenation of the system. Under shear, after a surprisingly long time, the spontaneous aging process observed at rest is suppressed. The system then reaches a nonequilibrium stationary state that is characterized by complex viscosity depending on the shear rate applied. In addition, the glass exhibits non-Newtonian shear-thinning behavior. This rheological behavior confirms recent numerical and theoretical predictions. © 2003 The Society of Rheology. @DOI: 10.1122/1.1574022#
منابع مشابه
Multiple nonergodic disordered states in Laponite suspensions: a phase diagram.
We study the time evolution of different Laponite suspensions from a low-viscosity ergodic state to a viscoelastic nonergodic state over a wide range of volume fractions and salt contents. We find that the evolution of nonergodicity parameter (Debye-Waller factor) splits into two branches for all the samples, which correspond to two distinct dynamically arrested states. At moderately high salt ...
متن کاملDelayed solidification of soft glasses: new experiments, and a theoretical challenge.
When subjected to large amplitude oscillatory shear stress, aqueous Laponite suspensions show an abrupt solidification transition after a long delay time t(c). We measure the dependence of t(c) on stress amplitude, frequency, and on the age-dependent initial loss modulus. At first sight our observations appear quantitatively consistent with a simple soft-glassy rheology (SGR)-type model, in whi...
متن کاملLocal rheological probes for complex fluids: application to Laponite suspensions.
We present an experimental method allowing a direct measurement of the local rheological behavior of complex fluids. A magnetic probe is inserted into the bulk of the fluid and submitted to a controlled magnetic force or torque, which induces a mechanical perturbation of the fluid. The geometry of the perturbation can be varied using two kinds of probes: a magnetic bead submitted to a homogeneo...
متن کاملSlow dynamics, aging, and glassy rheology in soft and living matter
We explore the origins of slow dynamics, aging and glassy rheology in soft and living matter. Non-diffusive slow dynamics and aging in materials characterised by crowding of the constituents can be explained in terms of structural rearrangement or remodelling events that occur within the jammed state. In this context, we introduce the jamming phase diagram proposed by Liu and Nagel to understan...
متن کاملRheological signatures of gelation and effect of shear melting on aging colloidal suspension
Colloidal suspensions that are out of thermodynamic equilibrium undergo physical aging wherein their structure evolves to lower the free energy. In aqueous suspension of Laponite, physical aging accompanies increases of elastic and viscous moduli as a function of time. In this work, we study temporal evolution of elastic and viscous moduli at different frequencies and observe that freshly prepa...
متن کامل