Montigny-lès-Metz, France
Montigny-lès-Metz, France

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Banchathanakij R.,Laboratoire Of Physique Des Milieux Denses | Greffier O.,Laboratoire Of Physique Des Milieux Denses | Becu L.,Laboratoire Of Physique Des Milieux Denses | Stebe M.J.,University of Lorraine | And 2 more authors.
Journal of Physical Chemistry B | Year: 2012

Micellar phases can be used as templates for the preparation of mesoporous silica materials. Fluorinated and hydrogenated surfactants can provide a large variety of well-defined micellar structures: spherical and cylindrical micelles as well as more complex structures such as lamellar or sponge phases can be formed in various thermodynamic conditions. However, the preparation of ordered mesoporous materials from these organized media is not always successful for a reason not known at the moment. It thus seems of the highest importance to properly characterize the micellar solution prior to the addition of the silica precursor during the material synthesis. In this paper, we describe some rheophysical properties of the micellar phase L1 prepared with a fluorinated surfactant, the formula of which is C7F 15C2H4(OC2H4) 8OH, labeled as RF7(EO)8. This surfactant forms micelles in water, and the direct micellar phases have been characterized in a wide range of temperatures and surfactant concentrations. The rheological properties of the L1 phase have also been studied as a function of temperature and concentration. Under steady and dynamic flow conditions, the solutions behave like Newtonian or shear thinning fluids depending on the temperature and surfactant concentration. A crossover between G′ and G″ is observed in the solution at the concentration of 20 wt % and at the temperature of 10 °C, suggesting the presence of long entangled micelles in solution at this temperature. When subjected to the action of a shearing device, the 20 wt % solution becomes optically anisotropic and shows flow birefringence, but the average orientation of the micelles quantified by the extinction angle π shows an unexpected behavior when the shear rate is gradually increased. © 2012 American Chemical Society.


Arbaoui J.,Laboratoire Of Physique Des Milieux Denses | Schmitt Y.,IUT de Thionville Yutz | Pierrot J.-L.,Laboratoire Of Physique Des Milieux Denses | Royer F.-X.,Laboratoire Of Physique Des Milieux Denses
Archives of Metallurgy and Materials | Year: 2014

Sandwich structures are widely used in lightweight construction especially in aerospace industries because of their high specific strength and stiffness. This paper investigates the effect of core thickness and intermediate layers on the mechanical properties of a polypropylene honeycomb core/composite facing multilayer sandwich structure under three points bending. We developed a theoretical model which makes it possible to calculate the shear properties in multi-cores. The results obtained by this model are agreed with our experimental results, and the results obtained with bending test showed that the mechanical properties of the composite multilayer structures increase with core thickness and intermediate layers.


PubMed | Laboratoire Of Physique Des Milieux Denses
Type: Journal Article | Journal: The journal of physical chemistry. B | Year: 2012

Micellar phases can be used as templates for the preparation of mesoporous silica materials. Fluorinated and hydrogenated surfactants can provide a large variety of well-defined micellar structures: spherical and cylindrical micelles as well as more complex structures such as lamellar or sponge phases can be formed in various thermodynamic conditions. However, the preparation of ordered mesoporous materials from these organized media is not always successful for a reason not known at the moment. It thus seems of the highest importance to properly characterize the micellar solution prior to the addition of the silica precursor during the material synthesis. In this paper, we describe some rheophysical properties of the micellar phase L(1) prepared with a fluorinated surfactant, the formula of which is C(7)F(15)C(2)H(4)(OC(2)H(4))(8)OH, labeled as R(F)(7)(EO)(8). This surfactant forms micelles in water, and the direct micellar phases have been characterized in a wide range of temperatures and surfactant concentrations. The rheological properties of the L(1) phase have also been studied as a function of temperature and concentration. Under steady and dynamic flow conditions, the solutions behave like Newtonian or shear thinning fluids depending on the temperature and surfactant concentration. A crossover between G and G is observed in the solution at the concentration of 20 wt % and at the temperature of 10 C, suggesting the presence of long entangled micelles in solution at this temperature. When subjected to the action of a shearing device, the 20 wt % solution becomes optically anisotropic and shows flow birefringence, but the average orientation of the micelles quantified by the extinction angle shows an unexpected behavior when the shear rate is gradually increased.

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