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Cesare Oliviero - One of the best experts on this subject based on the ideXlab platform.

  • Shear Rheology and phase behaviour of sodium oleate water mixtures
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007
    Co-Authors: Filipe E Antunes, Luigi Coppola, Danilo Gaudio, Isabella Nicotera, Cesare Oliviero
    Abstract:

    Abstract The knowledge of structural and dynamical properties in binary sodium oleate (NaO)/water mixtures represents a first step for studying new biocompatible structures. In addition, a deeper understanding of their flow behaviour is crucial to control their mechanical properties. The purpose of this investigation was to revisit the binary NaO/water phase diagram through a combined effort of Shear-Rheology, NMR-diffusometry, optical polarizing microscopy and differential scanning calorimetry. The preparation of NaO/water mixtures in this work fitted with the interesting regions of the phase diagrams where most of the new systems will be prepared (i.e. from 0.01 to 30 wt.% NaO and within the temperature range 5–70 °C). Steady Shear and linear viscoelastic experiments were accurately performed and the relationship between phase morphology and rheological properties was also studied. Regarding the mixtures at low surfactant concentrations, the Shear flow showed: (1) a structural evolution into the liquid micellar phase (L1) as a function of composition and (2) the presence of a viscous micellar region ( L 1 * ) induced by temperature and composition changes. NaO/water mixtures with a liquid-crystalline structure (hexagonal H1) were studied by linear Shear deformations and paying particular attention to frequency and temperature scans. Viscoelastic spectra of H1 phase presented a gel-like response which, although not expected, indicated the presence of a stiff liquid-crystalline lattice. Finally, a correlation between Rheology and microstructural changes was conducted by the “weak-gel” model.

  • Shear Rheology and phase behaviour of sodium oleate/water mixtures
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006
    Co-Authors: Filipe E Antunes, Luigi Coppola, Danilo Gaudio, Isabella Nicotera, Cesare Oliviero
    Abstract:

    Abstract The knowledge of structural and dynamical properties in binary sodium oleate (NaO)/water mixtures represents a first step for studying new biocompatible structures. In addition, a deeper understanding of their flow behaviour is crucial to control their mechanical properties. The purpose of this investigation was to revisit the binary NaO/water phase diagram through a combined effort of Shear-Rheology, NMR-diffusometry, optical polarizing microscopy and differential scanning calorimetry. The preparation of NaO/water mixtures in this work fitted with the interesting regions of the phase diagrams where most of the new systems will be prepared (i.e. from 0.01 to 30 wt.% NaO and within the temperature range 5–70 °C). Steady Shear and linear viscoelastic experiments were accurately performed and the relationship between phase morphology and rheological properties was also studied. Regarding the mixtures at low surfactant concentrations, the Shear flow showed: (1) a structural evolution into the liquid micellar phase (L1) as a function of composition and (2) the presence of a viscous micellar region ( L 1 * ) induced by temperature and composition changes. NaO/water mixtures with a liquid-crystalline structure (hexagonal H1) were studied by linear Shear deformations and paying particular attention to frequency and temperature scans. Viscoelastic spectra of H1 phase presented a gel-like response which, although not expected, indicated the presence of a stiff liquid-crystalline lattice. Finally, a correlation between Rheology and microstructural changes was conducted by the “weak-gel” model.

Dominique Langevin - One of the best experts on this subject based on the ideXlab platform.

  • On the use of Shear Rheology to formulate stable foams. Example of a lyotropic lamellar phase
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016
    Co-Authors: Zenaida Briceño-ahumada, Dominique Langevin, Armando Soltero, Amir Maldonado, Javier Pérez, Marianne Impéror-clerc
    Abstract:

    Abstract In order to formulate stable foams with gels, it is important to know their Shear Rheology properties. We illustrate this fact using a weak gel made of a lyotropic lamellar phase (SDS/hexanol/brine system). The effect of Shear is investigated using Rheology experiments coupled with Small Angle X-ray Scattering (rheo-SAXS) using synchrotron radiation. According to oscillatory tests, the samples exhibit a weak gel behavior. Steady state experiments evidence a Shear-induced transition from lamellar to onion (multilamellar vesicle – MLV) textures at moderate Shear rates. After the Shear is stopped, there is a recovery from the onion texture to the initial lamellar texture within 30 min, as directly demonstrated by the rheo-SAXS data. The lamellar to onion transition is therefore reversible. This excludes the possibility for the foams to be stabilized by onions adsorbed at the air–water interface as in foams made with other types of lamellar phases. In the example presented, the foam stability originates from the bulk rheological properties of the lamellar phase.

  • Surface Shear Rheology of monolayers at the surface of water.
    Advances in colloid and interface science, 2013
    Co-Authors: Dominique Langevin
    Abstract:

    The knowledge of surface Shear Rheology is important to understand and model flow in systems where interfaces are present: multiphase flow, wetting, foaming and others. The topic has been investigated for more than 100 years, but the knowledge accumulated is still partial. The experimental devices used for the measurement of the viscoelastic parameters are delicate to operate and the response of the monolayers is complex, usually non-linear and time dependent. Furthermore, it is difficult to decouple from the response of the bulk liquid. Important discrepancies between microscopic and macroscopic methods were reported and remain to be clarified. The knowledge of Shear properties does not suffice in general to achieve proper descriptions of the flow behavior and measurements of compression properties are needed as well. This paper presents examples taken from the literature and discusses the current level of understanding.

  • Shear Rheology of lipid monolayers and insights on membrane fluidity
    Proceedings of the National Academy of Sciences of the United States of America, 2011
    Co-Authors: Gabriel Espinosa, Francisco Monroy, Ivan Lopezmontero, Dominique Langevin
    Abstract:

    The concept of membrane fluidity usually refers to a high molecular mobility inside the lipid bilayer which enables lateral diffusion of embedded proteins. Fluids have the ability to flow under an applied Shear stress whereas solids resist Shear deformations. Biological membranes require both properties for their function: high lateral fluidity and structural rigidity. Consequently, an adequate account must include, in addition to viscosity, the possibility for a nonzero Shear modulus. This knowledge is still lacking as measurements of membrane Shear properties have remained incomplete so far. In the present contribution we report a surface Shear Rheology study of different lipid monolayers that model distinct biologically relevant situations. The results evidence a large variety of mechanical behavior under lateral Shear flow.

  • Interfacial Shear Rheology of Mixed Polyelectrolyte—Surfactant Layers
    Langmuir : the ACS journal of surfaces and colloids, 2009
    Co-Authors: Gabriel Espinosa, Dominique Langevin
    Abstract:

    We have studied the Shear Rheology of mixed surface layers containing polyelectrolytes and surfactants of opposite charges. The layers containing rigid polyelectrolytes are solidlike and can even exhibit brittle behavior. More flexible polyelectrolytes lead to more viscoelastic layers and very flexible ones to purely viscous layers. A relaxation time on the order of tens of seconds was found with the less flexible polymers. In the DNA case, it was possible to show that this relaxation time decreases with the inverse Shear rate, as in three-dimensional soft solids. These short times suggest that the polymer chains might not be entangled between the surface layers containing neutral polymers.

R Miller - One of the best experts on this subject based on the ideXlab platform.

  • Molecular weight dependence of the Shear Rheology of poly(methyl methacrylate) Langmuir films: a comparison between two different rheometry techniques.
    Langmuir : the ACS journal of surfaces and colloids, 2009
    Co-Authors: Armando Maestro, J Kragel, Francisco Ortega, Francisco Monroy, R Miller
    Abstract:

    The surface Shear Rheology of Langmuir monolayers of poly(methyl methacrylate) (PMMA) has been studied as a function of polymer concentration (Γ) and molecular weight (N). Two different Rheology te...

  • interfacial Shear Rheology of protein surfactant layers
    Advances in Colloid and Interface Science, 2008
    Co-Authors: J Kragel, S R Derkatch, R Miller
    Abstract:

    The Shear Rheology of adsorbed or spread layers at air/liquid and liquid/liquid phase boundaries is relevant in a wide range of technical applications such as mass transfer, monolayers, foaming, emulsification, oil recovery, or high speed coating. Interfacial Shear rheological properties can provide important information about interactions and molecular structure in the interfacial layer. A variety of measuring techniques have been proposed in the literature to measure interfacial Shear rheological properties and have been applied to pure protein or mixed protein adsorption layers at air/water or oil/water interfaces. Such systems play for example an important role as stabilizers in foams and emulsions. The aim of this contribution is to give a literature overview of interfacial Shear rheological studies of pure protein and protein/surfactant mixtures at liquid interfaces measured with different techniques. Techniques which utilize the damping of waves, spectroscopic or AFM techniques and all micro-rheological techniques will not discuss here.

  • Interfacial Shear Rheology of protein–surfactant layers
    Advances in Colloid and Interface Science, 2008
    Co-Authors: J Kragel, S R Derkatch, R Miller
    Abstract:

    The Shear Rheology of adsorbed or spread layers at air/liquid and liquid/liquid phase boundaries is relevant in a wide range of technical applications such as mass transfer, monolayers, foaming, emulsification, oil recovery, or high speed coating. Interfacial Shear rheological properties can provide important information about interactions and molecular structure in the interfacial layer. A variety of measuring techniques have been proposed in the literature to measure interfacial Shear rheological properties and have been applied to pure protein or mixed protein adsorption layers at air/water or oil/water interfaces. Such systems play for example an important role as stabilizers in foams and emulsions. The aim of this contribution is to give a literature overview of interfacial Shear rheological studies of pure protein and protein/surfactant mixtures at liquid interfaces measured with different techniques. Techniques which utilize the damping of waves, spectroscopic or AFM techniques and all micro-rheological techniques will not discuss here.

  • Studies of asdorption and surface Shear Rheology of mixed β-lactoglobulin/surfactant systems
    Progress in Colloid & Polymer Science, 1
    Co-Authors: J Kragel, David C. Clark, Peter J. Wilde, R Miller
    Abstract:

    The structure of mixed β-lactoglobulin/Tween 20 adsorption layers was studied by surface Shear rheological and dynamic surface tension measurements. Surface Shear Rheology was carried out with a torsion pendulum set-up which provides information about the surface Shear viscosity and elasticity in one single experiment.

S R Derkatch - One of the best experts on this subject based on the ideXlab platform.

  • Interfacial Shear Rheology
    Current Opinion in Colloid & Interface Science, 2010
    Co-Authors: J Kragel, S R Derkatch
    Abstract:

    This review summarises the interfacial Shear Rheology in the context of problems occurring during the measuring process. The main areas covered are surfactants, proteins, macromolecules, monolayers, particles or mixed systems at the gas/liquid and liquid/liquid interface. New developments in measuring techniques, in data analysis, modelling and theory will be discussed, while micro-rheological techniques using optical or magnetic tweezers are not in the scope of this contribution.

  • interfacial Shear Rheology of protein surfactant layers
    Advances in Colloid and Interface Science, 2008
    Co-Authors: J Kragel, S R Derkatch, R Miller
    Abstract:

    The Shear Rheology of adsorbed or spread layers at air/liquid and liquid/liquid phase boundaries is relevant in a wide range of technical applications such as mass transfer, monolayers, foaming, emulsification, oil recovery, or high speed coating. Interfacial Shear rheological properties can provide important information about interactions and molecular structure in the interfacial layer. A variety of measuring techniques have been proposed in the literature to measure interfacial Shear rheological properties and have been applied to pure protein or mixed protein adsorption layers at air/water or oil/water interfaces. Such systems play for example an important role as stabilizers in foams and emulsions. The aim of this contribution is to give a literature overview of interfacial Shear rheological studies of pure protein and protein/surfactant mixtures at liquid interfaces measured with different techniques. Techniques which utilize the damping of waves, spectroscopic or AFM techniques and all micro-rheological techniques will not discuss here.

  • Interfacial Shear Rheology of protein–surfactant layers
    Advances in Colloid and Interface Science, 2008
    Co-Authors: J Kragel, S R Derkatch, R Miller
    Abstract:

    The Shear Rheology of adsorbed or spread layers at air/liquid and liquid/liquid phase boundaries is relevant in a wide range of technical applications such as mass transfer, monolayers, foaming, emulsification, oil recovery, or high speed coating. Interfacial Shear rheological properties can provide important information about interactions and molecular structure in the interfacial layer. A variety of measuring techniques have been proposed in the literature to measure interfacial Shear rheological properties and have been applied to pure protein or mixed protein adsorption layers at air/water or oil/water interfaces. Such systems play for example an important role as stabilizers in foams and emulsions. The aim of this contribution is to give a literature overview of interfacial Shear rheological studies of pure protein and protein/surfactant mixtures at liquid interfaces measured with different techniques. Techniques which utilize the damping of waves, spectroscopic or AFM techniques and all micro-rheological techniques will not discuss here.

J Kragel - One of the best experts on this subject based on the ideXlab platform.

  • Interfacial Shear Rheology
    Current Opinion in Colloid & Interface Science, 2010
    Co-Authors: J Kragel, S R Derkatch
    Abstract:

    This review summarises the interfacial Shear Rheology in the context of problems occurring during the measuring process. The main areas covered are surfactants, proteins, macromolecules, monolayers, particles or mixed systems at the gas/liquid and liquid/liquid interface. New developments in measuring techniques, in data analysis, modelling and theory will be discussed, while micro-rheological techniques using optical or magnetic tweezers are not in the scope of this contribution.

  • Molecular weight dependence of the Shear Rheology of poly(methyl methacrylate) Langmuir films: a comparison between two different rheometry techniques.
    Langmuir : the ACS journal of surfaces and colloids, 2009
    Co-Authors: Armando Maestro, J Kragel, Francisco Ortega, Francisco Monroy, R Miller
    Abstract:

    The surface Shear Rheology of Langmuir monolayers of poly(methyl methacrylate) (PMMA) has been studied as a function of polymer concentration (Γ) and molecular weight (N). Two different Rheology te...

  • interfacial Shear Rheology of protein surfactant layers
    Advances in Colloid and Interface Science, 2008
    Co-Authors: J Kragel, S R Derkatch, R Miller
    Abstract:

    The Shear Rheology of adsorbed or spread layers at air/liquid and liquid/liquid phase boundaries is relevant in a wide range of technical applications such as mass transfer, monolayers, foaming, emulsification, oil recovery, or high speed coating. Interfacial Shear rheological properties can provide important information about interactions and molecular structure in the interfacial layer. A variety of measuring techniques have been proposed in the literature to measure interfacial Shear rheological properties and have been applied to pure protein or mixed protein adsorption layers at air/water or oil/water interfaces. Such systems play for example an important role as stabilizers in foams and emulsions. The aim of this contribution is to give a literature overview of interfacial Shear rheological studies of pure protein and protein/surfactant mixtures at liquid interfaces measured with different techniques. Techniques which utilize the damping of waves, spectroscopic or AFM techniques and all micro-rheological techniques will not discuss here.

  • Interfacial Shear Rheology of protein–surfactant layers
    Advances in Colloid and Interface Science, 2008
    Co-Authors: J Kragel, S R Derkatch, R Miller
    Abstract:

    The Shear Rheology of adsorbed or spread layers at air/liquid and liquid/liquid phase boundaries is relevant in a wide range of technical applications such as mass transfer, monolayers, foaming, emulsification, oil recovery, or high speed coating. Interfacial Shear rheological properties can provide important information about interactions and molecular structure in the interfacial layer. A variety of measuring techniques have been proposed in the literature to measure interfacial Shear rheological properties and have been applied to pure protein or mixed protein adsorption layers at air/water or oil/water interfaces. Such systems play for example an important role as stabilizers in foams and emulsions. The aim of this contribution is to give a literature overview of interfacial Shear rheological studies of pure protein and protein/surfactant mixtures at liquid interfaces measured with different techniques. Techniques which utilize the damping of waves, spectroscopic or AFM techniques and all micro-rheological techniques will not discuss here.

  • Studies of asdorption and surface Shear Rheology of mixed β-lactoglobulin/surfactant systems
    Progress in Colloid & Polymer Science, 1
    Co-Authors: J Kragel, David C. Clark, Peter J. Wilde, R Miller
    Abstract:

    The structure of mixed β-lactoglobulin/Tween 20 adsorption layers was studied by surface Shear rheological and dynamic surface tension measurements. Surface Shear Rheology was carried out with a torsion pendulum set-up which provides information about the surface Shear viscosity and elasticity in one single experiment.