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John Embery
UK Polymer Showcase 2007 - Innovative Materials
Appl. Rheol. 18:2 (2008) 125-126 ►
► Cite this publication as follows:
Embery J: UK Polymer Showcase 2007 - Innovative Materials, Appl. Rheol. 18 (2008) 125.Martin Zatloukal
Novel Trends in Rheology II
Appl. Rheol. 18:2 (2008) 124-124 ►
► Cite this publication as follows:
Zatloukal M: Novel Trends in Rheology II, Appl. Rheol. 18 (2008) 124.
Technical fibre flows are normally flocky, but have theoretically mainly been treated as individual fibre flows. The reason for this can only be understood in the context of historic development. In Part 1 of this historic investigation the roots of fibre flow research are traced to the beginning of the 19th century.The subsequent development is followed through its formative period in the first half of the 20th century up to about WW2. Part 2 will continue up to about 1960s when the present main tradition had been well established. In Part 2, an example of an alternative approach will also be given, and some proposals for future development presented.► Cite this publication as follows:
Bjorkman U: The Nonlinear History of Fibre Flow Research: Part 1. Background and Beginning, Appl. Rheol. 18 (2008) 23974.
Electrorheological fluids (ERF) change viscosity when an electric field is applied. A special type of ERF consists of polyurethane particles which are doped with Li+ and/or Zn2+ cations and suspended in silicone oil.This article gives an overview of the temperature dependent behavior of the ER effect for these fluids and describes the basic principles how this is explained. Chemical analyses provide information as a basis for a polarization model in several dimensions down to molecular size.► Cite this publication as follows:
Schneider S, Eibl S: Review of the Electrorheological (ER) Effect of Polyurethane-based ER Fluids, Appl. Rheol. 18 (2008) 23956.
Rheological behavior of asphalt is strongly affected by loading conditions, temperature and environment. One of the main challenges in understanding the rheology of asphalt is to relate the chemical constituents and the micro-structure of asphalt on one hand to its rheological behavior on the other hand. In this work, nonlinear rheological behaviour of asphalt was investigated using a structural rheological model. A first order kinetic equation to describe structural changes in asphalt has been incorporated with the nonlinear rheological model of White- Metzner. The resulting set of governing equations was solved numerically to describe the rheology of asphalts. Different modes of rheological testing and asphalts with different compositions were considered. An analysis and comparison of model behaviour with experimental data from the literature is carried out in both stress growth at constant shear rate and oscillatory shear modes. A strategy is proposed for the estimation and tuning of the model parameters based on available experimental data and literature. Qualitatively, the model can capture the rheological behaviour of non-Newtonian fluids such as asphalt under different modes of rheological testing. Quantitative analysis from this work shows that the model describes the rheological behaviour of asphalt for the temperature range of 20 - 60oC. It is demonstrated that a single set of equations tuned with the steady shear experimental data can be used to predict the nonlinear rheological behaviour of asphalts. In addition, it is shown that the model parameters can be related to the chemical composition of asphalts.► Cite this publication as follows:
Vijay R, Deshpande AP, Varughese S: Nonlinear rheological modeling of asphalt using White-Metzner model with structural parameter variation based asphaltene structural build-up and breakage, Appl. Rheol. 18 (2008) 23214.
Small micellar casein particles were formed in aqueous solutions of native casein after addition of polyphosphate. These socalled submicelles aggregated and gelled with a rate that increased with increasing temperature.The evolution of the viscosity during this process was determined at constant shear rate or shear stress. When applying a small shear stress the viscosity increased strongly until the shear rate became immeasurably slow, but when the applied shear stress exceeded a critical value (σc) the aggregates broke up and the viscosity reached a maximum. At longer times the viscosity decreased rapidly at first, followed by a very slow decrease. sc was independent of the shear rate and heating temperature, but increased strongly with increasing casein concentration.At constant shear rate the stress remained close to σc, but fluctuated irregularly.After cessation of shear flow, gels were formed rapidly. Oscillation shear measurements for σ > σc showed a strongly non-linear response at the time of maximum viscosity.► Cite this publication as follows:
Pitkowski A, Nicolai T, Durand D: Shear flow and large amplitude oscillation shear study of solutions of aggregating micellar casein particles, Appl. Rheol. 18 (2008) 23050.
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