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Matteo Papa, Roberta Pedrazzani, Stefano Nembrini
Should rheological properties of activated sludge be measured?

Appl. Rheol. 25:2 (2015) 24590 (6 pages)

The core of activated sludge monitoring lies in the biological analyses. Anyway, the knowledge of sludge physical characteristics is crucial for a proper management of WWTPs (Waste Water Treatment Plants). One of these physical features is viscosity that, notwithstanding its valuable role has not yet become a routine analysis. This study examined the evolution of rheological properties of two sludges alongside the .purification route. (from the biological reactor up to the sludge treatments). It could been shown that sludges behaved like non-Newtonian fluids and dry solids content strongly affected viscosity values, which reached relatively high values. Microscopic observation of flocs was carried out. Both the sludges revealed similar features, in particular an over-proliferation of filamentous bacteria. This work showed how rheological measurements can be a tool to obtain information on microbiological composition of activated sludge and how it could be related to settleability properties.

Cite this publication as follows:
Papa M, Pedrazzani R, Nembrini S: Should rheological properties of activated sludge be measured?, Appl. Rheol. 25 (2015) 24590.

Amir Saadat, Hossein Nazockdast, Fatemeh Sepehr, Milad Mehranpoor
Viscoelastic modeling of extrudate swell of AcryloNi.Rile-Butadiene-Styrene/Clay nanocomposite

Appl. Rheol. 23:1 (2013) 12131 (11 pages)

The aim of the present work was to predict the extrudate swelling behavior of organoclay containing AcryloNi.Rile- Butadiene-Styrene (ABS) nanocomposite. The modeling was performed on the basis of unconstrained recovery concept originally introduced by Tanner but employing Wagner viscoelastic model with generalized Wagner damping function which is believed to be capable of taking into account the effect of organoclay on viscoelastic properties of nanocomposite sample. This approach enabled us to evaluate the effect of organoclay on extrudate swell in terms of disentanglement kinetics and chain relaxation behavior. In our modeling, the effect of die entrance region on the extent of extrudate swelling was also considered. In order to evaluate the validity of our modeling, the extrudate swell was measured as a function of wall shear stress for samples varying in organoclay content. The results predicted from the model were found to be in relatively good agreement with the experimental results.

Cite this publication as follows:
Saadat A, Nazockdast H, Sepehr F, Mehranpoor M: Viscoelastic modeling of extrudate swell of Acrylonitrile-Butadiene-Styrene/Clay nanocomposite, Appl. Rheol. 23 (2013) 12131.

Luigi Gentile, Giuseppina De Luca, Filipe E. Antunes, Cesare Oliviero Rossi, Giuseppe Antonio RaNi.Ri
Thermogelation Analysis Of F127-Water Mixtures By Physical Chemistry Techniques

Appl. Rheol. 20:5 (2010) 52081 (9 pages)

Aqueous solutions of F127 pluronic systems exhibit an interesting thermal gelation above a certain concentration. This phenomenon concerns the transition from a liquid-like behavior at low temperatures to a solid-like behavior at high temperatures, and it is due to different temperature responses from the different polymer segments, polypropylene oxide (PPO) and polyethylene oxide (PEO). Such property leads to a structural change in the self assembled macromolecule upon heating, from an isotropic micellar structure to an ordered cubic structure. These two types of assembly are clearly distinct with respect to their rheological behavior.This contribution emphasizes the rheological properties of the pluronic system in micellar and cubic phase, in combination with NMR, Dynamic Light Scattering and DSC information. The results emphasize the gelation process upon heating and a cubic phase characterized by higher storage modulus and higher A and z Weak Gel Model exponents than the micellar phase. Micellar growth upon heating was found within micellar phase. The presented data support the hypothesis that each polymer segment actively participates in the formation of the different phases: while PPO is responsible for micelle formation, PEO plays a dominating role in cubic phase formation. Finally, different stiffness between the core and the corona of the aggregates in the two phases is observed.

Cite this publication as follows:
Gentile L, DeLuca G, Antunes FE, OlivieroRossi C, Ranieri GA: Thermogelation Analysis Of F127-Water Mixtures By Physical Chemistry Techniques, Appl. Rheol. 20 (2010) 52081.

D.C. Venerus, J. Buongiorno, R. Christianson, J. Townsend, I.C. Bang, G. Chen, S.J. Chung, M. Chyu, H. Chen, Y. Ding, F. Dubois, G. Dzido, D. Funfschilling, Q. Galand, J. Gao, H. Hong, M. Horton, Lin-wen Hu, C.S. Iorio, A.B. Jarzebski, Y. Jiang, S. Kabelac, M.A Kedzierski, C. Kim, Ji-Hyun Kim, S. Kim, T. McKrell, R. Ni, J. Philip, N. Prabhat, P. Song, S. Van Vaerenbergh, D. Wen, S. Witharana, Xiao-Zheng Zhao, Sheng-Qi Zhou
Viscosity measurements on colloidal dispersions (nanofluids) for heat transfer applications

Appl. Rheol. 20:4 (2010) 44582 (7 pages)

This article reports viscosity data on a series of colloidal dispersions collected as part of the International Nanofluid Property Benchmark Exercise (INPBE). Data are reported for seven different fluids that include dispersions of metal-oxide nanoparticles in water, and in synthetic oil. These fluids, which are also referred to as 'nanofluids,' are currently being researched for their potential to function as heat transfer fluids. In a recently published paper from the INPBE study, thermal conductivity data from more than 30 laboratories around the world were reported and analyzed. Here, we examine the influence of particle shape and concentration on the viscosity of these same nanofluids and compare data to predictions from classical theories on suspension rheology.

Cite this publication as follows:
Venerus DC, Buongiorno J, Christianson R, Townsend J, Bang I, Chen G, Chung S, Chyu M, Chen H, Ding Y, Dubois F, Dzido G, Funfschilling D, Galand Q, Gao J, Hong H, Horton M, Hu L-W, Iorio CS, Jarzebski AB, Jiang Y, Kabelac S, Kedzierski MA, Kim C, Kim J-H, Kim S, McKrell T, Ni R, Philip J, Prabhat N, Song P, VanVaerenbergh S, Wen D, Witharana S, Zhao X-Z, Zhou S-Q: Viscosity measurements on colloidal dispersions (nanofluids) for heat transfer applications, Appl. Rheol. 20 (2010) 44582.

Dmitry Borin, Piotr Ni.Rityuk, Stefan Odenbach
On the magnetic field influence on the viscosity of liquid GaInSn with suspended solid particles

Appl. Rheol. 19:6 (2009) 61995 (7 pages)

Experimental and numerical studies have been undertaken to check the influence of a magnetic field on the viscosity of liquid GaInSn with suspended solid particles.The rheological investigations show a significant change of the slope of the measured flow curves between the situation B = 0 and 0.02 T. By means of numerical simulations of the flow in the presence of Lorentz forces it could be shown that the influence of magnetohydrodynamic damping of the flow reduces the measured changes but does not annihilate them. As conclusion a 15 % change of viscosity of the melt in a magnetic field with B = 0.02 T could be fixed.

Cite this publication as follows:
Borin D, Nikrityuk P, Odenbach S: On the magnetic field influence on the viscosity of liquid GaInSn with suspended solid particles, Appl. Rheol. 19 (2009) 61995.

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