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Larbi Hammadi, Alain Ponton
Rheological investigation of vase of dam: effects of aging time, shear rate and temperature

Appl. Rheol. 27:1 (2017) 14667 (9 pages)

In this paper we investigate the rheological complex behavior of a vase of Fergoug dam which is located in the region Perregaux (Western Algeria) as a function of aging time, shear rate, and temperature. The modified Herschel-Bulkley model is used to fit the stationary flow curves of vase as a function of aging time and the generalized model of Kelvin-Voigt is successfully applied to fit the creep and recovery data and to analyze the viscoelastic properties of vase as a function of temperature. Finally the thixotropic behavior studied at constant temperature is analyzed by using the Herschel-Bulkley model including a structural parameter in order to account for time dependent effect. It is demonstrated that the increase in shear rate induces a restructuring and reorganization of the particles of the vase at the microstructural level.

Cite this publication as follows:
Hammadi L, Ponton A: Rheological investigation of vase of dam: effects of aging time, shear rate and temperature, Appl. Rheol. 27 (2017) 14667.

Florentina Talos, Alain Ponton, Berengere Abou, Alexandre Chevillot, Helene Lecoq, Simion Simon
Multiscale viscoelastic investigation of silica-calcium-phosphate sol-gel materials

Appl. Rheol. 25:6 (2015) 63567 (12 pages)

The sol-gel transition of homogeneous biocomposites synthesized using tetraethyl-orthosilicate alkoxide, calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate salts as reagents are investigated at the macroscopic scale by small amplitude oscillatory shear measurements and probed locally by passive microrheology at 37 C. Structural evolutions during the sol-gel transition are studied by using Fourier Transform Infrared (FT-IR) analysis. The Young's modulus of the aged gels is measured as a function of time, at room temperature. Moreover the materials are dried, thermally treated and characterized by laser scattering analysis and X-ray diffraction to obtain the particle size distribution and crystallite size respectively and to observe the morphology by Scanning Electron Microscopy.

Cite this publication as follows:
Talos F, Ponton A, Abou B, Chevillot A, Lecoq H, Simon S: Multiscale viscoelastic investigation of silica-calcium-phosphate sol-gel materials, Appl. Rheol. 25 (2015) 63567.

Alain Ponton, Claire Meyer, Guillaume Foyart, Luc Aymard, Karim Djellab
Structural and thermomechanical investigation of lyotropic liquid crystal phases doped with monodisperse microparticles

Appl. Rheol. 24:1 (2014) 14147 (7 pages)

We present a study of the structural and thermomechanical properties of lyotropic phase in the quasi ternary system made of Cetylpyridinium chloride (CPCl)/hexanol/salt water (0.9% by mass) with and without cobalt microparticles. Phase transition temperatures of the structural sequence isotropic L1/nematic calamitic Nc,/hexagonal H have been determined by differential scanning microcalorimetry. Temperature induced developable domains in hexagonal phase H and disclinations in calamitic nematic phase Nc were observed in crossed polar optical microscopy in confined geometry. A rheological study of calamitic nematic phase Nc highlighted structuring effect of cobalt microparticles from a concentration of 2% to be demonstrated by an increase in viscosity and viscoelastic moduli. This could be explained by a stabilization of disclinations.

Cite this publication as follows:
Ponton A, Meyer C, Foyart G, Aymard L, Djellab K: Structural and thermomechanical investigation of lyotropic liquid crystal phases doped with monodisperse microparticles, Appl. Rheol. 24 (2014) 14147.

M. Guettari, I. Ben Naceur, G. Kassab, A. Ponton, T. Tajouri
Temperature and concentration induced complex behavior in ternary microemulsion

Appl. Rheol. 23:4 (2013) 44966 (7 pages)

Viscosity measurements were performed in water/AOT (sodium bis(2-ethylhexyl) sulfoccinate)/isooctane microemulsions as a function of temperature between 25 C and 55 C, molar ratio Wo = water/AOT ranging from 3 to 45 and three values of AOT/isooctane volume fractions (Φm = 0.1, 0.15, and 0.2). It was shown that microemulsions behaved as Newtonian fluids in the studied range of shear rate. For a critical molar ratio, Woc, the corresponding viscosity, ηoc, was shown to be constant with temperature but dependent on the micellar concentration. For Wo < Woc, the solutions behaved as simple fluids and the temperature dependence of viscosity was described by an Arrhenius law. The total activation energy was found to be dependent on W with a maximum for Wo = 5. A correlation between the microscopic structure of the reverse micelles and the total activation energy was proposed. However, a complex fluid behavior was observed for Wo > Woc, where the viscosity increased with temperature. For some values of Wo, the viscosity reached a maximum, which could be explained by attractive interdroplet interactions and formation of droplet clusters.

Cite this publication as follows:
Guettari M, BenNaceur I, Kassab G, Ponton A, Tajouri T: Temperature and concentration induced complex behavior in ternary microemulsion, Appl. Rheol. 23 (2013) 44966.


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