Aging of Soft Glassy Materials Probed by Rheology and Light Scattering

摘要

Aging of soft glassy materials studied by rheology, small-angle Dynamic Light Scattering (DLS) and Diffusing Wave Spectroscopy (DWS) is presented. We use these methods to obtain the dynamic signature of aging for various colloidal systems such as compressed water-in-oil emulsions, mixtures of surfactant, oil and water, and xanthan pastes. In all cases, we observe a significant reduction in the colloidal mobility with sample age as derived from measured intensity correlation functions. For all systems, an unusual shape of the age-dependent part of the correlation functions was found, ruling out conventional diffusive mobility. Using an analogy between molecular and colloidal glasses, we analyze a violation of the Generalized Stokes-Einstein Relation using a combination of DWS and rheology.