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Petra Peer, Martin Stenicka, Petr Filip, Vladimir Pavlinek
Comparison of Electrorheological Measurements Based on Different Methods of Electric Field Generation

Appl. Rheol. 24:4 (2014) 42875 (4 pages)

Electrorheological measurements represent a key approach in characterizing the efficiency of electrorheological fluids. The rotational rheometers, the Physica MCR 501 (Anton Paar) equipped with an electrorheological cell and the Bohlin Gemini CVOR 150 (Malvern Instruments) modified for electrorheological experiments generate an electric field in two completely different ways. Each of the two generations has a specific influence on electrorheological measurements. The experimental data were obtained and compared for a suspension of polyaniline powders mixed (10 wt%) in silicone oil. For a concentric-cylinders arrangement, it was shown that the data are fully comparable for both rheometers. However, for a parallel-plate arrangement, the data using the Physica MCR 501 provide higher values in comparison with both the corresponding plateplate data obtained with the Bohlin Gemini CVOR 150 and with the mutually comparable concentric cylinders data.

Cite this publication as follows:
Peer P, Stenicka M, Filip P, Pavlinek V: Comparison of Electrorheological Measurements Based on Different Methods of Electric Field Generation, Appl. Rheol. 24 (2014) 42875.

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.

Martin Stenicka, Vladimir Pavlinek, Petr Saha, Natalia V Blinova, Jaroslav Stejskal, Otakar Quadrat
Electrorheology of suspensions of variously protonated polyaniline particles under steady and oscillatory shear

Appl. Rheol. 20:5 (2010) 55371 (7 pages)


Electrorheological (ER) and dielectric properties of silicone-oil suspensions of polyaniline (PANI) particles protonated with phosphoric and tetrafluoroboric acids to various doping level have been investigated. The particle conductivity was thus varied between the order of 10-9 S/cm and 10-4 S/cm. The dynamic yield stresses obtained at controlled shear rate mode viscometry, the storage moduli from the oscillatory shear experiments and the dielectric relaxation times from frequency dependences of dielectric constant and loss factor were used as criteria of rigidity or elasticity of ER structures and particle mobility in the electric field. The conductivity of suspension particles plays a decisive role in their ER behaviour. The ER efficiency increased as conductivity of dispersed particles raised, irrespective of the type of employed acid used for the protonation of PANI.

Cite this publication as follows:
Stenicka M, Pavlinek V, Saha P, Blinova NV, Stejskal J, Quadrat O: Electrorheology of suspensions of variously protonated polyaniline particles under steady and oscillatory shear, Appl. Rheol. 20 (2010) 55371.

V. Pavlinek, P. Saha, K. Perez-Gonzalez, L. de Vargas, J. Stejskal, O. Quadrat
Analysis of the Yielding Behavior of Electrorheological Suspensions by Controlled Shear Stress Experiments

Appl. Rheol. 16:1 (2006) 14-18

The yielding behavior of two model electrorheological suspensions of uncoated silica particles and silica coated with polyaniline base in silicone oil using controlled shear rate and controlled shear stress experiments has been analyzed. The results demonstrate that unlike the uncertain dynamic yield stress values estimated from the results obtained in the former mode by extrapolation of the unsteady shear stresses to zero shear rate, the controlled shear stress measurement permits to detect sensitively the region starting from the initial rupture of particle chain structure in the electric field at rest corresponding to a static yield stress and ending in total breakage of suspension structure at a breaking stress. The latter quantity can be detected with a good accuracy and proved to be a reliable criterion of the stiffness of electrorheological (ER) structure.

Cite this publication as follows:
Pavlinek V, Saha P, Perez-Gonzalez J, DeVargas L, Stejskal J, Quadrat O: Analysis of the Yielding Behavior of Electrorheological Suspensions by Controlled Shear Stress Experiments, Appl. Rheol. 16 (2006) 14.

V. Pavlinek, P. Saha, T. Kitano, T. Tanegashima
Influence of the Electric Field on the Electrorheological Behaviour of Cellulose Suspensions in Silicone Oils

Appl. Rheol. 9:2 (1999) 64-68

Cite this publication as follows:
Pavlinek V, Saha P, Kitano T, Tanegashima T: Influence of the Electric Field on the Electrorheological Behaviour of Cellulose Suspensions in Silicone Oils, Appl. Rheol. 9 (1999) 64.


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