%0 Book Section %1 statphys23_0985 %A Wyss, H.M. %A Mattsson, J. %A Miyazaki, K. %A Reichman, D.R. %A Weitz, D.A. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K glassy materials relaxation rheology soft statphys23 structural topic-7 %T Rheological probes of the relaxation dynamics of densely packed soft colloids %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=985 %X Densely packed deformable colloids such as foams or compressed emulsions exhibit fascinating mechanial and dynamical properties; while they consist entirely of viscous components, their macroscopic rheological behavior is elastic-like within the time scales accessible to oscillatory rheology. They show the viscoelastic behavior typical for soft glassy materials, which suggests that a slow structural relaxation process should dominate their rheology at low frequencies. Here we use a new approach to oscillatry rheology, which we term Strain-Rate Frequency Superposition (SRFS), to obtain detailed information on the structural relaxation process in this class of materials. By probing different oscillation frequencies at a constant strain rate amplitude, our approach allows us to study the dependence of slow relaxation processes on an applied strain rate. Our results indicate that strain rate acts as an effective temperature, speeding up the relaxation processes in the system to a range of frequencies where they can be directly probed. We exploit this behavior to identify key differences in the relaxation dynamics of different soft glassy materials; notably we detect a secondary relaxation process in foams that is intimately linked to the main structural relaxation, with a time scale that shows the same strain rate dependent scaling behavior. We present a simple model description that qualitatively accounts for the observed behavior.

@incollection{statphys23_0985, abstract = {Densely packed deformable colloids such as foams or compressed emulsions exhibit fascinating mechanial and dynamical properties; while they consist entirely of viscous components, their macroscopic rheological behavior is elastic-like within the time scales accessible to oscillatory rheology. They show the viscoelastic behavior typical for soft glassy materials, which suggests that a slow structural relaxation process should dominate their rheology at low frequencies. Here we use a new approach to oscillatry rheology, which we term Strain-Rate Frequency Superposition (SRFS), to obtain detailed information on the structural relaxation process in this class of materials. By probing different oscillation frequencies at a constant strain rate amplitude, our approach allows us to study the dependence of slow relaxation processes on an applied strain rate. Our results indicate that strain rate acts as an effective temperature, speeding up the relaxation processes in the system to a range of frequencies where they can be directly probed. We exploit this behavior to identify key differences in the relaxation dynamics of different soft glassy materials; notably we detect a secondary relaxation process in foams that is intimately linked to the main structural relaxation, with a time scale that shows the same strain rate dependent scaling behavior. We present a simple model description that qualitatively accounts for the observed behavior.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Wyss, H.M. and Mattsson, J. and Miyazaki, K. and Reichman, D.R. and Weitz, D.A.}, biburl = {https://www.bibsonomy.org/bibtex/227d42e548367a2ad8a1dd6a1bc76328e/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {db9d68b2c5eae3c38eee8e8df1f72cd1}, intrahash = {27d42e548367a2ad8a1dd6a1bc76328e}, keywords = {glassy materials relaxation rheology soft statphys23 structural topic-7}, month = {9-13 July}, timestamp = {2007-06-20T10:16:36.000+0200}, title = {Rheological probes of the relaxation dynamics of densely packed soft colloids}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=985}, year = 2007 }