Applied Rheology: Publications

Appl Rheol online available publications for selected issue

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S. Ahzi, S. Patlazhan, Y. Remond, M. Khaleel
Third International Conference on Polymer Behavior (Marrakech, Marocco, 2008)

Appl. Rheol. 19:4 (2009) 247-249

Cite this publication as follows:
Ahzi S, Patlazhan S, Remond Y, Khaleel M: Third International Conference on Polymer Behavior (Marrakech, Marocco, 2008), Appl. Rheol. 19 (2009) 247.

Delegates of the national rheological societies
Society's Site Sep 2009 - Feb 2010

Appl. Rheol. 19:4 (2009) 257-266

Cite this publication as follows:
Rheological Societies: Society's Site Sep 2009 - Feb 2010, Appl. Rheol. 19 (2009) 257.

Philippe Coussot, Nadja El Kissi, Jean-Francois Tassin
De Gennes Discussion Conference 2009, a brief survey

Appl. Rheol. 19:4 (2009) 250-251

Cite this publication as follows:
Coussot P, Kissi NE, Tassin J-F: De Gennes Discussion Conference 2009, a brief survey, Appl. Rheol. 19 (2009) 250.

Ernest Carl McIntyre, Frank E. Filisko
Squeeze Flow Rheology of Zeolite Suspensions

Appl. Rheol. 19:4 (2009) 44322 (8 pages)

Aggregation, heterogeneous flows, and complex particle geometries all pose challenges in rheology. This paper uses squeeze flow rheometry techniques to examine a case, where all of these played a role. The applicability of some squeeze theories is tested, and the ability to predict results based on suspension theories is examined. The squeeze flow data is shown to deviate from Stefan's Law [Stefan J, Sitz. Kais. Akad. Wiss. Math. Nat. Wien 69 (1874) 713-735]. The suspension rheology deviated from predicted theory, but by taking into account particle effects such as aggregation the fit to the empirical Maron-Pierce equation [Maron SH and PE Pierce, J. Coll. Sci. 11 (1956) 80-95] could be understood. The conclusions of this study show how using only squeeze flow techniques the synergistic nature of these effects can be better understood.

Cite this publication as follows:
McIntyre EC, Filisko FE: Squeeze Flow Rheology of Zeolite Suspensions, Appl. Rheol. 19 (2009) 44322.

Ulf Bjorkman
The non-Newtonian Fluid Mechanics of Technical Fibre Suspensions: Compressive Flows

Appl. Rheol. 19:4 (2009) 44290 (24 pages)

The flow of non-Newtonian technical fibre suspensions (paper pulps) through a number of contractions is analysed and compared. Traditionally technical fibre flows are modelled as flow of fibres in a suspending medium. Here they are treated as crowded flows of fibre flocs from which the liquid may be squeezed in and out from. Compressive flows are common in the fibre-based process industry. They can e.g. be found in the headbox of a paper machine, in extruder nozzles in polymer technology, in the stirrer zone of mixers, etc. Traditionally such flows are analysed in elongational flow terms. Here it will be demonstrated that elongational and compressive flows for technical fibres suspensions differ qualitatively. The nature of technical fibre flocs is also discussed. For historic reasons they have come to be regarded as the outcome of a flocculation process of electrostatic-colloidal and/or mechanical-entanglement type. It will be shown that such a process is unnecessary for technical fibre suspensions and that these flocs are qualitatively different, viz. frozen-developed dissipative structures of the flocky fibre flow from which they originate. It will also be demonstrated that technical fibre flocs, in contrast with flocs of the chemically flocked type, are basically non-coherent, i.e. not kept together by themselves. It is this non-coherence that makes a compressive approach fruitful, for these economically important flows. An attempt to explain the reasons behind the present state of fibre flow theory is presented. The ambition is to stop to the present inproductive tradition in technical fibre flow.

Cite this publication as follows:
Bjorkman U: The non-Newtonian Fluid Mechanics of Technical Fibre Suspensions: Compressive Flows, Appl. Rheol. 19 (2009) 44290.

Filipe E. Antunes, Luigi Gentile, Lorena Tavano, Cesare Oliviero Rossi
Rheological characterization of the thermal gelation of poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)co-Acrylic Acid

Appl. Rheol. 19:4 (2009) 42064 (9 pages)

The combined effect of charged addition and molecular weight, Mw, on the thermal gelation and gel dissolution of poly(Nisopropylacrylamide) chains was explored by using Rheological techniques. The synthesized charged derivative is poly(N-isopropylacrylamide co-Acrylic acid). The rheological behavior of the two macromolecules is clearly different: the thermal gelation of the high Mw and charged macromolecule is much more accentuated. This suggests that the gelation at high temperatures only occurs when the inter polymer aggregate distance is sufficiently short to allow polymer bridging; this situation can be achieved by different approaches, such as increasing polymer concentration and increasing polymer persistence length and polymer Mw.

Cite this publication as follows:
Antunes FE, Gentile L, Tavano L, OlivieroRossi C: Rheological characterization of the thermal gelation of poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)co-Acrylic Acid, Appl. Rheol. 19 (2009) 42064.

Katarzyna Niedzwiedz, Oliver Arnolds, Norbert Willenbacher, Rudiger Brummer
Capillary Breakup Extensional Rheometry of Yield Stress Fluids

Appl. Rheol. 19:4 (2009) 41969 (10 pages)

Filament breakup of high viscosity fluids with apparent yield stress has been investigated and strategies for an appropriate characterization of their behavior in CaBER experiments are discussed. Filament profiles of such fluids exhibit significant concave curvature. Accurate determination of filament shape is mandatory for understanding deformation behavior. Therefore, we have set up an optical train including high-speed camera, telecentric objective and telecentric back-light illumination with a blue light emitting diode (LED) providing high contrast filament shape imaging. Image analysis allows for diameter determination with an accuracy of 3.55 μm/pixel. In addition to the transient filament diameter at the neck we have extracted the curvature at this point as a function of time and the region of deformation, in order to characterize the extensional flow behavior.We have investigated the time evolution of filament shape as a function of various experimental parameters like stretching time, velocity profile during stretching, stretching ratio and initial sample volume at constant stretching ratio. Filament thinning is independent of stretching time, tsub>s and stretching velocity profile. But when the same stretching ratio is applied at different initial volume fraction, filament curvature increases strongly with decreasing sample volume leading to an increase of filament life time according to the negative contribution of its curvature to the Laplace pressure inside the fluid.

Cite this publication as follows:
Niedzwiedz K, Arnolds O, Willenbacher N, Brummer R: Capillary Breakup Extensional Rheometry of Yield Stress Fluids, Appl. Rheol. 19 (2009) 41969.


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