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The European Physical Journal E

, Volume 9, Issue 3, pp 287–291 | Cite as

Anomalous dynamical light scattering in soft glassy gels

  • J.-P. Bouchaud
  • E. Pitard

Abstract:

We compute the dynamical structure factor S(q,τ) of an elastic medium where force dipoles appear at random in space and in time, due to “micro-collapses” of the structure. Various regimes are found, depending on the wave vector q and the collapse time θ. In an early time regime, the logarithm of the structure factor behaves as (qτ)3/2, as predicted in (L. Cipelletti et al., Phys. Rev Lett. 84, 2275 (2000)) using heuristic arguments. However, in an intermediate-time regime we rather obtain a (qτ)5/4 behaviour. Finally, the asymptotic long-time regime is found to behave as q3/2τ. We also give a plausible scenario for aging, in terms of a strain-dependent energy barrier for micro-collapses. The relaxation time is found to grow with the age tw, quasi-exponentially at first, and then as tw4/5 with logarithmic corrections.

PACS. 82.70.Gg Gels and sols – 81.40.Cd Solid solution hardening, precipitation hardening, and dispersion hardening; aging 

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Copyright information

© EDP Sciences, Springer-Verlag, Società Italiana di Fisica 2002

Authors and Affiliations

  • J.-P. Bouchaud
    • 1
  • E. Pitard
    • 2
  1. 1.Service de Physique de l'État Condensé, Centre d'études de Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, FranceFR
  2. 2.Laboratoire de Physique Mathématique et Théorique, Université Montpellier II, UMR 5825, FranceFR

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