Ultraslow dynamics and stress relaxation in the aging of a soft glassy system.
We use linear rheology and multispeckle dynamic light scattering (MDLS) to investigate the aging of a gel composed of multilamellar vesicles. Light scattering data indicate rearrangement of the gel through an unusual ultraslow ballistic motion. A dramatic slowdown of the dynamics with sample age t(w) is observed for both rheology and MDLS, the characteristic relaxation time scaling as t(mu)w. We find the same aging exponent mu = 0.78 for both techniques, suggesting that they probe similar physical processes, that is the relaxation of applied or internal stresses for rheology or MDLS, respectively. A simple phenomenological model is developed to account for the observed dynamics.
Ramos
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Groupe de Dynamique des Phases Condensées (UMR 5581), Université Montpellier 2, 34095 Montpellier Cedex 5, France.
Cipelletti
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