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Off-equilibrium surface tension in driven colloidaland polymer suspensions
Auteur(s): Truzzolillo D., Cipelletti L., Dupas C., Mora S.
Conference: Micromast, 1st International Conference on Multiscale Applications of Surface Tension (Brussels, BE, 2016-09-05)
Ref HAL: hal-01937340_v1
Exporter : BibTex | endNote
Résumé: We report the measurement of non-equilibrium interfacial tension of polymer and hard sphere suspensions in contact with their own solvent. By visualizing fingering instability (VF) in radial Hele-Shaw geometry, we measure interfacial tension in function of the volume fraction of the suspensions showing that the internal degrees of freedom of the particles drive the magnitude of such tension. We rationalize our findings proposing a phenomenological model capturing the compositional dependence of the non equilibrium interfacial tension for the whole range of concentration gradients and for all the systems at hand. More generally we propose the analysis of fluid dynamic instabilities as a new tool to measure interfacial tensions between complex fluids.
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Rheology, microscopic dynamics and material failure in the creep of a colloidal gel
Auteur(s): Cipelletti L., Ramos L., Aime S.
Conference: Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications (Schloss Hernstein, AT, 2016-07-10)
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Microscopic dynamics of polymer samples under tensile stress
Auteur(s): Cipelletti L.
Conférence invité: 3rd International Workshop on Nonlinear Response in Complex Matter (Primošten, HR, 2016-09-26)
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Microscopic dynamics and macroscopic rheology in a semi-crystalline polymer
Auteur(s): Cipelletti L.
Conférence invité: International Conference on Multiscale Materials Modeling (Dijon, FR, 2016-10-19)
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Scattering Techniques
Auteur(s): Cipelletti L., Trappe Veronique, Pine D. J.
Chapître d'ouvrage: Fluids, Colloids And Soft Materials, vol. p.131-148 (2016)
Ref HAL: hal-01934656_v1
Exporter : BibTex | endNote
Résumé: Scattering techniques can average over many more particles than can direct methods and thus often provide much better quantitative measurements of the average structural and dynamical properties of materials. Scattering techniques generally work best when the wavelength of the radiation is about the same as the size of the structures that scatter the radiation. The basic principle underlying light scattering can be grasped by considering the intensity of the light scattered by two particles within the scattering volume. Dynamic light scattering (DLS) takes note of particular fact and uses the time dependence of the flickering speckles to quantitatively characterize the underlying motion of the scatterers. Scattering methods based on imaging geometries have been developed, such as Photon Correlation Imaging and Near Field Scattering. In differential dynamic microscopy (DDM), one takes again advantage of a differential algorithm.
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A stress-controlled shear cell for small-angle light scattering and microscopy
Auteur(s): Aime S., Ramos L., Fromental J.-M., Prevot G., Jelinek R., Cipelletti L.
(Article) Publié:
Review Of Scientific Instruments, vol. 87 p.123907 (2016)
Texte intégral en Openaccess :
Ref HAL: hal-01292652_v1
Ref Arxiv: 1603.06703
DOI: 10.1063/1.4972253
WoS: 000392096800036
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
10 Citations
Résumé: We develop and thoroughly test a stress-controlled, parallel plates shear cell that can be coupled to an optical microscope or a small angle light scattering setup, for simultaneous investigation of the rheological properties and the microscopic structure of soft materials under an imposed shear stress. In order to minimize friction, the cell is based on an air bearing linear stage, the stress is applied through a contactless magnetic actuator, and the strain is measured through optical sensors. We discuss the contributions of inertia and of the small residual friction to the measured signal and demonstrate the performance of our device in both oscillating and step stress experiments on a variety of viscoelastic materials.
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Space-resolved diffusing wave spectroscopy measurements of the macroscopic deformation and the microscopic dynamics in tensile strain tests
Auteur(s): Nagazi M. Y., Brambilla G., Meunier Gérard, Marguerès Philippe, Périé Jean-Noël, Cipelletti L.
(Article) Publié:
Optics And Lasers In Engineering, vol. 88 p.5 - 12 (2016)
Texte intégral en Openaccess :
Ref HAL: hal-01292690_v1
Ref Arxiv: 1603.06384
DOI: 10.1016/j.optlaseng.2016.07.006
WoS: 000385319500002
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
16 Citations
Résumé: We couple a laser-based, space-resolved dynamic light scattering apparatus to a universal testing machine for mechanical extensional tests. We perform simultaneous optical and mechanical measurements on polyether ether ketone, a semi-crystalline polymer widely used in the industry. Due to the high turbidity of the sample, light is multiply scattered by the sample and the diffusing wave spectroscopy (DWS) formalism is used to interpret the data. Space-resolved DWS yields spatial maps of the sample strain and of the microscopic dynamics. An excellent agreement is found between the strain maps thus obtained and those measured by a conventional stereo-correlation bench. The microscopic dynamics reveals both affine motion and plastic rearrangements. Thanks to the extreme sensitivity of DWS to displacements as small as 1 nm, plastic activity and its spatial localization can be detected at an early stage of the sample deformation, making the technique presented here a valuable complement to existing material characterization methods.
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