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Thomas Mezger
Basics of Rheology Workshop 2011

Appl. Rheol. 21:5 (2011) 303-304

Cite this publication as follows:
Mezger T: Basics of Rheology Workshop 2011, Appl. Rheol. 21 (2011) 303.

Sami Seyfert, Arnold Uhl
International Workshop Dispersion Analysis (Berlin, 2011)

Appl. Rheol. 21:5 (2011) 300-303

Cite this publication as follows:
Seyfert S, Uhl A: International Workshop Dispersion Analysis (Berlin, 2011), Appl. Rheol. 21 (2011) 300.

Julian Oberdisse, Anne-Caroline Genix, Marc Couty, Gerald J. Schneider, Wim Pyckhout-Hintzen
3rd European Workshop on Nanocomposites and Polymer Dynamics (2011)

Appl. Rheol. 21:5 (2011) 299-300

Cite this publication as follows:
Oberdisse J, Genix A, Couty M, Schneider GJ, Pyckhout-Hintzen W: 3rd European Workshop on Nanocomposites and Polymer Dynamics (2011), Appl. Rheol. 21 (2011) 299.

Arnaud Perrot, Yannick Melenge, Patrice Estelle, Damien Rangeard, Christophe Lanos
The back extrusion test as a technique for determining the rheological and tribological behaviour of yield stress fluids at low shear rates

Appl. Rheol. 21:5 (2011) 53642 (10 pages)

A new method is developed to determine the rheological and tribological behaviour of viscoplastic fluids using a back extrusion test. In back extrusion geometry, the material is forced to flow in the gap between the inner and the outer cylinder. Such a flow is modelled by a Bingham constitutive law under different wall boundary conditions (stick, slip with friction and perfect slip). When steady-state flow is reached, an apparent shear rate is computed. The analysis of the inner cylinder penetration force versus the penetration depth helps us to develop a method to identify the fluid rheological and tribological properties. This method is based on an inverse analysis to identify the fluid behaviour parameters from experiments performed at different ram velocities and with different apparatus geometries. In order to study more complex fluids (Herschell-bulkley rheological behaviour, for example), an equivalent flow curve is plotted from tests characterized by different average shear rates. The tribological behaviour is identified using different wall boundary conditions, varying the surface roughness of the cylinders. The method is applied to oil/sugar suspension and plasticine. Rheological and tribological behaviours are identified and results are compared with those obtained under steady state shear flow. The obtained rheological parameters are close to those provided by the common rheological methods (difference lower than 15 %).

Cite this publication as follows:
Perrot A, Melinge Y, Estelle, Rangeard D, Lanos C: The back extrusion test as a technique for determining the rheological and tribological behaviour of yield stress fluids at low shear rates, Appl. Rheol. 21 (2011) 53642.

N. Ouari, A. Kaci, A. Tahakourt, M. Chaouche
Rheological behaviour of fibre suspensions in non-Newtonian fluids

Appl. Rheol. 21:5 (2011) 54801 (10 pages)

The influence of short fibre addition on the rheological behaviour of different non-Newtonian fluids is investigated experimentally. Two types of suspending fluids are considered: power-law shear thinning fluids and yieldstress shear-thinning fluids. The power-law suspending fluids consist of aqueous xanthan solutions at different concentrations. The yield stress fluids are mortar tile adhesives characterised by different rheological parameters. The flow curves of the suspensions at different fibre contents are determined at controlled stresses. Three rheological parameters are inferred from the flow curves: the yield stress, the consistency and the fluidity index. The influence of the fibres on the rheological behaviour of purely shear-thinning fluids is found to be quite similar to what can be expected for Newtonian suspending fluids. On the other hand, addition of fibres to yield stress granular fluids leads to a qualitatively different change of their rheological properties compared to the case of Newtonian suspending fluids. In particular, it is found that the fibres can lead to the decrease of the apparent viscosity and the yield stress for low fibre concentrations in the case of granular suspending fluids. Our experimental findings indicate that the models for fibre suspensions in Newtonian solvents cannot be used straightforwardly in the case of fibre suspensions in granular materials such as building materials, ceramic materials, etc.

Cite this publication as follows:
Ouari N, Kaci A, Tahakourt A, Chaouche M: Rheological behaviour of fibre suspensions in non-Newtonian fluids, Appl. Rheol. 21 (2011) 54801.

H.W. Tan, M. Misran, S.K. Khoo
Viscoelastic Behavior of Olive Oil-in-Water Emulsion Stabilized By Sucrose Fatty Acid Esters

Appl. Rheol. 21:5 (2011) 54599 (9 pages)

The rheological behavior of the olive oil-in-water emulsions has been studied by varying the oil to water ratio as well as the surfactant concentration. The viscoelastic property of the olive oil emulsions was investigated with a cone-and-plate system, using a Bohlin C-VOR Rheometer. The obtained results indicated that the emulsions with greater oil and surfactant concentrations are highly packed systems with greater interdroplet interactions as well as higher critical strain. The viscoelastic property of the emulsions can be enhanced by increasing the oil concentration. The elastic modulus of the emulsions was always predominant over the viscous modulus, thereby emphasizing the elastic character of the above mentioned emulsions. The emulsion with a higher oil composition shows greater elasticity, which implies a strong dynamic rigidity of the emulsions. A high oil composition also enhanced the structural integrity as well as the interdroplet interactions of the emulsion.

Cite this publication as follows:
Tan H, Misran M, Khoo S: Viscoelastic Behavior of Olive Oil-in-Water Emulsion Stabilized By Sucrose Fatty Acid Esters, Appl. Rheol. 21 (2011) 54599.

Miroslav Mrlik, Vladimir Pavlinek, Petr Saha, Otakar Quadrat
Electrorheological properties of suspensions of polypyrrole coated titanate nanorods

Appl. Rheol. 21:5 (2011) 52365 (7 pages)

The behaviour of silicone-oil suspensions of titanate nanorods coated with polypyrrole base in electric field has been investigated. Unlike suspension of globular particles of neat polypyrrole, rod-like particles show a stronger electrorheological (ER) effect corresponding to high rigidity of the structure. A great influence of the oil viscosity on the ER efficiency was observed. A good reproducibility of the effect and a fast response to the switching-on and -off the electric field has been confirmed by monitoring the time course of shear stress under controlled shear rate.

Cite this publication as follows:
Mrlik M, Pavlinek V, Saha P, Quadrat O: Electrorheological properties of suspensions of polypyrrole coated titanate nanorods, Appl. Rheol. 21 (2011) 52365.


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