Applied Rheology: Publications

Appl Rheol online available publications for selected issue

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Delegates of the national rheological societies
Society's Site Sep 2004 - Feb 2005

Appl. Rheol. 14:4 (2004) 215-225

Cite this publication as follows:
Rheological Societies, Emri I, Mielke W, Fischer P, Urska FS: Society's Site Sep 2004 - Feb 2005 , Appl. Rheol. 14 (2004) 215.

Martin Kroger, Peter Fischer
Patents Review (Aug 2004)

Appl. Rheol. 14:4 (2004) 207-209

Cite this publication as follows:
Kroger M, Fischer P: Patents Review (Aug 2004) , Appl. Rheol. 14 (2004) 207.

Petra Roth
RheoFuture Conference 2004

Appl. Rheol. 14:4 (2004) 204-205

Cite this publication as follows:
Roth P: RheoFuture Conference 2004, Appl. Rheol. 14 (2004) 204.

N. Katsikis
Rheology of Disperse Systems (German Society of Rheology 2004 Workshop)

Appl. Rheol. 14:4 (2004) 202-203

Cite this publication as follows:
Katsikis N: Rheology of Disperse Systems (German Society of Rheology 2004 Workshop), Appl. Rheol. 14 (2004) 202.

Thomas Schweizer
A Quick Guide to Better Viscosity Measurements of Highly Viscous Fluids

Appl. Rheol. 14:4 (2004) 197-201

The performance of tests with elastic liquids at high shear rates is cumbersome due to viscous dissipation heating, high normal forces, and - above all - edge fracture. This paper shows how such measurements can be improved and simplified over the conventional cone-plate technique by using a partitioned plate. For a polystyrene melt with zero shear viscosity 44.5 kPas at 190.C, steady state viscosities can be obtained up to 100 s-1. For samples with twice the diameter of the sensing area of the tool, the strain beyond which disturbances can be noticed is about 2 - 3 times higher than for conventional cone-plate. As a consequence of the design, precise viscosity measurements can be made without knowing the exact radius of the sample and without well centring it. This geometry is ideal for quick and dirty loading. Drawbacks are that the tool requires regular cleaning of the ring gap, that it can only be fitted to rheometers with a non-displacing force measuring cell (force rebalance transducer), and that it is not suited to measure low viscous systems such as polymer solutions.

Cite this publication as follows:
Schweizer T: A Quick Guide to Better Viscosity Measurements of Highly Viscous Fluids, Appl. Rheol. 14 (2004) 197.

J.M. Valverde, A.T. Perez, A. Castellanos, R.E. Viturro
Rheological Testing of Xerographic Liquid Inks: A Need for Printing Technology

Appl. Rheol. 14:4 (2004) 190-196

Rheological properties of xerographic liquid inks of different concentrations of solid particles have been tested. Generally we have found that viscosity decreases with increasing shear rate, i.e. the system is pseudoplastic as corresponds to the break down of aggregated particles by the applied shear. The viscosity of inks may vary in orders of magnitude depending on solids concentration, reaching up values of ~ 108 Pas for solids concentration of 40 wt%. The existence of a yield critical stress has been discussed and we estimate that it increases exponentially with solids concentration. We have looked for possible differences in the rheological behavior of ink samples obtained either diluting more concentrated inks or drying less concentrated ones. Concentration and dilution of xerographic inks do not change their rheological properties meaning that the microscopic structure of the concentrated dispersion is broken (when diluting) and recovered (when drying) reversibly. On the other hand processed ink (previously subjected to high mechanical and electrostatic stresses) behaves differently than non-processed ink. The properties of processed inks are not totally recovered when diluting, manifesting itself in a higher effective apparent viscosity. This result should be of main concern to liquid ink based printing technologies, for which elimination of waste by recycling processed ink is a major goal.

Cite this publication as follows:
Valverde JM, Perez AT, Castellanos A, Viturro RE: Rheological Testing of Xerographic Liquid Inks: A Need for Printing Technology, Appl. Rheol. 14 (2004) 190.

Gholamhossein Sodeifian, Ali Haghtalab
Discrete Relaxation Spectrum and K-BKZ Constitutive Equation for PVC, NBR and Their Blends

Appl. Rheol. 14:4 (2004) 180-189

Frequency sweep experiments were performed on poly(vinyl chloride) (PVC) and acrylonitrile butadiene rubber (NBR) as well as their miscible blends PVC/NBR (70/30), PVC/NBR (50/50), and PVC/NBR (30/70) in oscillatory shear. The samples were prepared by mechanical blending at 160.C. In order to investigate the validity of time temperature superposition (TTS) principle the loss angle d versus the logarithm of the absolute value of the complex modulus, G*, were plotted. It was shown that the TTS principle is not valid for the above-mentioned polymer materials and therefore they are not thermorheologically simple. Master curves of PVC, NBR, and PVC/NBR (50/50) blend were therefore obtained approximately. Using a nonlinear regression method, discrete relaxation spectra were determined for PVC, NBR, and PVC/NBR (50/50). To study non-linear viscoelasticity behavior, the experiments of steady shear, start up steady shear, and step strain were carried out. The damping function was determined by the step strain experiments. Using K-BKZ constitutive equation, the shear viscosity and the shear stress growth function were calculated from the discrete relaxation spectra and the damping function and then compared to experimental data. The K-BKZ constitutive equation provides very good prediction over the entire range of experimental results.

Cite this publication as follows:
Sodeifian G, Haghtalab A: Discrete Relaxation Spectrum and K-BKZ Constitutive Equation for PVC, NBR and Their Blends, Appl. Rheol. 14 (2004) 180.

Martin Kroger
Ferrofluids: Magnetically Controllable Fluids and Their Applications (Stefan Odenbach)

Appl. Rheol. 14:4 (2004) 178

Cite this publication as follows:
Kroger M: Ferrofluids: Magnetically Controllable Fluids and Their Applications (Stefan Odenbach), Appl. Rheol. 14 (2004) 178.


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