arXiv subjects

Luca Cipelletti

Publications and source records attributed to Luca Cipelletti.

58 records · Page 4Linked to original sources

arXiv2004

Heterogeneous Dynamics of Coarsening Systems

We show by means of experiments, theory and simulations, that the slow dynamics of coarsening systems displays dynamic heterogeneity similar to that observed in glass-forming systems. We measure dynamic heterogeneity via novel multi-point functions which quantify the emergence of dynamic, as opposed to static, correlations of fluctuations. Experiments are performed on a coarsening foam using Time Resolved Correlation, a recently introduced light scattering method. Theoretically we study the Ising model, and present exact results in one dimension, and numerical results in two dimensions. For all systems the same dynamic scaling of fluctuations with domain size is observed.

cond-mat.stat-mech↗

arXiv2004

Analysis by the Two-Fluids Model of the Dynamical Behavior of a Viscoelastic Fluid Probed by Dynamic Light Scattering

The dynamic properties of a model transient network have been studied by dynamic light scattering. The network is formed by microemulsion droplets linked by telechelic polymers (modified hydrophilic polymers with two grafted hydrophobic stickers). We compare the properties of two networks that are similar but for the residence time of the hydrophobic stickers in the droplets. The results are interpreted according to the so-called two-fluids model, which was initially developed for semidilute polymer solutions and which we extend here to any Maxwellian viscoelastic medium characterized by its elastic modulus and terminal time as measured by rheology. This model is found to describe consistently and quantitatively the experimental observations.

cond-mat.soft↗

arXiv2003

Intermittency and non-Gaussian fluctuations in the dynamics of aging colloidal gels

This paper has been temporarily withdrawn by the authors. We have recently found that noise in the experiments is at the origin of the supposed "back-and-forth" motion which is discussed in the first version of the paper. As a consequence, figs 4 and 5 as well as their discussion are incorrect. Figure 1 and the general trend of fig. 2 are still valid. At this time, we are uncertain whether or not the short time behavior of cI, shown in fig. 3, is affected by measurement noise. We are working on a new version of the paper, using new techniques that allow us to correct for the experimental noise.

cond-mat.soft↗

arXiv2001

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 $t_{w}^μ$. We find the same aging exponent $μ=0.78$ 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.

cond-mat.soft↗