We attribute similarities in the rheology of many soft materials (foams, emulsions, slurries, etc.) to shared features structural disorder and metastability. A generic model for mesoscopic dynamics ``soft glassy matter'' is introduced, with interactions represented by a mean-field noise temperature x. find power law fluid behavior either (x<1) or without (1<x<2) yield stress. For 1<x<2, both storage loss modulus vary frequency as $\omega^{x-1}$, becoming flat near glass transition (x=1)....

Filled elastomers exhibit a complex dependence of their viscoelastic modulus as function both temperature and frequency. Otherwise, recent observations on thin polymer films have shown that glass transition depends thickness. On the basis these results model, we propose mechanical behavior filled elastomer is strongly influenced by gradient in vicinity particles. This allows us to suggest specific temperature−frequency superposition law for rubbers. seems apply very successfully two systems...

The dynamics of the polymer matrix in filled rubbers is modified by presence solid particles. We used low-field proton NMR to investigate model samples consisting a dispersion grafted silica particles into an elastomeric matrix. Exploiting magic-sandwich echo experiments, we were able determine fraction with slower and correlate it specific surface. immobilized polymer—most probably due gradient glass transition temperature around particles—is detected whether there covalent bond between...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLinear and nonlinear viscoelasticity of semidilute solutions wormlike micelles at high salt contentA. Khatory, F. Lequeux, Kern, S. J. CandauCite this: Langmuir 1993, 9, 6, 1456–1464Publication Date (Print):June 1, 1993Publication History Published online1 May 2002Published inissue 1 June 1993https://pubs.acs.org/doi/10.1021/la00030a005https://doi.org/10.1021/la00030a005research-articleACS PublicationsRequest reuse permissionsArticle...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDynamic Properties of Salt-Free Viscoelastic Micellar SolutionsF. Kern, F. Lequeux, R. Zana, and S. J. CandauCite this: Langmuir 1994, 10, 6, 1714–1723Publication Date (Print):June 1, 1994Publication History Published online1 May 2002Published inissue 1 June 1994https://pubs.acs.org/doi/10.1021/la00018a018https://doi.org/10.1021/la00018a018research-articleACS PublicationsRequest reuse permissionsArticle Views1208Altmetric-Citations329LEARN ABOUT...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEntangled versus multiconnected network of wormlike micellesA. Khatory, F. Kern, Lequeux, J. Appell, G. Porte, N. Morie, A. Ott, and W. UrbachCite this: Langmuir 1993, 9, 4, 933–939Publication Date (Print):April 1, 1993Publication History Published online1 May 2002Published inissue 1 April 1993https://pubs.acs.org/doi/10.1021/la00028a010https://doi.org/10.1021/la00028a010research-articleACS PublicationsRequest reuse permissionsArticle...

In this paper, we introduce a simple mode-coupling model for concentrated suspensions under flow . This exhibits jamming transition, and stress vs shear rate relations which are very similar to experimental results. Namely newtonian regime or yield followed by slow variation of the higher rates, an apparent large rates. Another striking result is that oscillating strain, even in jammed state, system relaxation time depends on strain amplitude.

We report the modifications of microscopic dynamics a colloidal glass submitted to shear. use multispeckle diffusing wave spectroscopy monitor evolution spontaneous slow relaxation processes after samples have been various straining. show that high shear rejuvenates system and accelerates its dynamics, whereas moderate over-ages system. analyze these phenomena within frame Bouchaud's trap model.

The effect of connection between giant wormlike micelles is studied. We calculate the diffusion rate, which increased by sliding connections. viscosity weakly reduced connections in case scission-recombination reactions.

We use diffusing-wave spectroscopy to measure the motion of droplets in concentrated emulsions subjected a periodic shear strain. The strain gives rise echoes correlation function which decay with increasing amplitude. For given amplitude, implies that finite fraction emulsion never rearranges under while remaining repeatedly rearranges. Yielding occurs when about 4--5% rearrange.

We use optical techniques to study the aging behavior of glassy colloidal suspensions Laponite, a synthetic Hectorite clay. Multi-speckle diffusing wave spectroscopy measurements tracer particle motion in Laponite show that slow collective relaxation time τ medium scales linearly with age tw sample, universal feature many systems. Moreover, mean-square displacement particles terminal regime as ⟨Δr2(tw,t)⟩ ∼ (t/tw)γ, where γ = 1.5 ± 0.1. Light scattering studies pure scattered light intensity...

In an attempt to establish connections between classical rheology and aging in paste colloidal suspensions, we report this paper a large set of experimental results on given system. We have studied suspensions polyethylene oxide-protected silica particles performed experiments that exhibit very nonlinear behavior. then evidenced through stress relaxation as observed various glassy systems, finally show other manifestations rheological experiments. Qualitative agreement these the predictions...

The slowing-down of the dynamics a polymer chain near surface has been observed for many years now. Here we show that behavior model nanocomposites can be quantitatively described with gradient glass-transition temperature. We describe single parameter---the range this gradient---the temperature and solvent effect on spin relaxation dynamics. Moreover, parameter allows quantitative description nanocomposite calorimetric response from one bulk polymer.

We study the adsorption dynamics of an azobenzene-based photo-responsive charged surfactant to investigate how photo-stimulation impacts at air–water interface. The hydrophobic tail this photo-converts reversibly from a cis trans conformation when wavelength switches UV blue. This change in results decrease surface tension. Using kinetically limited model adsorption, including electrostatics effects and competition between two photo-isomers, we reproduce AzoTAB measured experimentally. find...

Powders of nanoparticles are volatile, i.e. easily disperse in air, which makes their handling difficult. Granulation nanoparticle powders provides a solution to that issue, and it is generally performed by spray drying the have been suspended liquid. Spray colloidal suspension consists atomising into droplets fast flowing hot gas. Once dried, resulting dry grains/microparticles can be used wide range applications - food, pharmaceutics, fillers, ceramics, etc. It well known grains from...

We report evidence for photocontrolled stability and breakage of aqueous foams made from solutions a cationic azobenzene-containing surfactant over wide range concentrations. Exposure to UV or visible lights results in shape polarity switches the molecule, which turn affects several properties including critical micelle concentration, equilibrium surface tension, air-water interfacial composition (cis isomers are displaced by trans ones). demonstrate that isomer stabilizes foams, whereas cis...

The reinforcement of elastomers by inorganic fillers, a concept very high technological importance, is commonly understood to result from the presence mechanical network partially aggregated filler particles. non-linear properties, in particular decrease modulus at strain (Payne effect), are further interpreted be consequence breakdown this network. There are, however, many open questions concerning actual nature interparticle connections, where modified polymer layer forming "glassy...

We analyze the influence of a glass transition gradient near particle surfaces on nonlinear mechanical behavior reinforced elastomers. studied systems consisting grafted silica particles dispersed in cross-linked poly(ethyl acrylate) matrix. Both particle/matrix interfaces and dispersion states have been precisely characterized. On basis previous studies same evidencing around particles, we show that precocious these filled is related to strain-softening glassy polymer shell surrounding...

The aging behavior of colloidal suspensions laponite, a model synthetic clay, is investigated using light scattering techniques. In order to measure the complete dynamic structure factor as function time and wave vector, we have developed an original optical setup multispeckle technique for simple scattering. We thus measured correlation scattered intensity age sample t(w) various concentrations. For sufficiently concentrated samples, observe two-stage relaxation process. fast diffusive,...

A multispeckle technique for efficiently measuring correctly ensemble-averaged intensity autocorrelation functions of scattered light from nonergodic and/or nonstationary systems is described. The method employs a charge coupled device (CCD) camera as detector and computer-based correlator, permits the simultaneous calculation up to 500 correlation functions, where each function started at different time. are calculated in real time referenced unique starting nature CCD means that true...

By studying model systems consisting of poly(ethyl acrylate) polymer chains covalently bound to silica particles, we show here how the temperature dependence modulus filled elastomers can be explained by a long-ranged gradient matrix glass transition in vicinity particles. We are led this conclusion comparing NMR and mechanical data. thereby that mechanisms reinforcement same as those which lead an increase strongly adsorbed thin films. It allows us particular propose new time-temperature...