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A.J. Nogueiro, J.M. Maia
On the Influence of Concentration on the Rheology of Polymer Solutions:Can Scaling Laws Be Found?

Appl. Rheol. 13:2 (2003) 87-92

The present work is concerned with the study of the rheology of polymer solutions spanning different concentration regimes and originates from a former round-robin research programme on this subject, the S1 project, involving a number of research groups and institutions. The base fluid for this programme was the so-called S1 fluid, which is a 2.5% w/w solution of Polyisobutylene (PIB) in a solvent consisting of a mixture of polybutene oil and dekalin. In this paper a set of solutions having different concentrations of PIB are studied in steady shear, oscillatory shear and in axi-symmetrical contraction flows. The focus of the study is on the possibility of finding concentration scaling laws for polymer solutions spanning each or several of the concentration regimes. The results in shear flows show that it is possible to find scaling laws both for temperature and concentration in all regimes. Extensional results show that the curves superimpose within each concentration regime, but not over the whole range of concentrations. Accordingly, concentration scaling laws were then found for both shear and extension, the latter depending on the concentration regime: dilute, semi-dilute or concentrated.

Cite this publication as follows:
Nogueiro AJ, Maia JM: On the Influence of Concentration on the Rheology of Polymer Solutions:Can Scaling Laws Be Found?, Appl. Rheol. 13 (2003) 87.

J.M.Maia, O.S.Carneiro, A.V.Machado, J.A.Covas
On-Line Rheometry for Twin-Screw Extrusion (Along the Extruder) and its Applications

Appl. Rheol. 12:1 (2002) 18-24

Due to a number of practical difficulties, both in- and on-line measurements of the rheological properties of complex systems during extrusion are usually performed at the end of the extruder, under very specific experimental conditions. This makes this type of instruments more useful for quality control than for process optimisation, since information about the influence of the geometry and/or processing conditions on the evolution of the material characteristics inside the extruder is not easily gathered. Recently, however, the authors have developed an on-line capillary rheometry system that overcomes most of the existing problems and allows small amounts of sample to be tested in very near real time, along the extruder. The present work aims at illustrating the usefulness of this concept for the study of physical compounding processes and some reactive systems. Two very different systems will be used for that purpose: a reactive extrusion process (the peroxide-induced thermal degradation of polypropylene) and the dispersive mixing involved in the preparation of thermoplastic/carbon fibre composites.

Cite this publication as follows:
Maia JM, Carneiro OS, Machado AV, Covas JA: On-Line Rheometry for Twin-Screw Extrusion (Along the Extruder) and its Applications, Appl. Rheol. 12 (2002) 18.

Joao M. Maia
Numerical and analytical methods in non-Newtonian fluid mechanics

Appl. Rheol. 11:5 (2001) 287

Cite this publication as follows:
Maia JM: Numerical and analytical methods in non-Newtonian fluid mechanics, Appl. Rheol. 11 (2001) 287.

I. M. Afonso, J. M. Maia
Rheological Monitoring of Structure Development and Rebodying of Set-Style Yoghurt

Appl. Rheol. 10:2 (2000) 73-79

Cite this publication as follows:
Afonso IM, Maia JM: Rheological Monitoring of Structure Development and Rebodying of Set-Style Yoghurt, Appl. Rheol. 10 (2000) 73.


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