Applied Rheology: Publications

Appl Rheol online available publications for selected issue

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Jasna Zelko, J. Ravi Prakash, Burkhard Duenweg
Fluid-Structure Interactions in Soft-Matter Systems: From the Mesoscale to the Macroscale (Prato, 2012)

Appl. Rheol. 23:2 (2013) 124-125

Cite this publication as follows:
Zelko J, Prakash JR, Duenweg B: Fluid-Structure Interactions in Soft-Matter Systems: From the Mesoscale to the Macroscale (Prato, 2012), Appl. Rheol. 23 (2013) 124.

Wu Ge
Turbulent Drag Reduction by Surfactant Additives (FC Li, B Yu, JJ Wei, Y Kawaguchi)

Appl. Rheol. 23:2 (2013) 84-85

Cite this publication as follows:
Ge W: Turbulent Drag Reduction by Surfactant Additives (FC Li, B Yu, JJ Wei, Y Kawaguchi), Appl. Rheol. 23 (2013) 84.

Arsia Takeh, Sachin Shanbhag
A Computer Program to Extract the Continuous and Discrete Relaxation Spectra from Dynamic Viscoelastic Measurements

Appl. Rheol. 23:2 (2013) 24628 (10 pages)

We describe and implement an efficient, open-source, multi-platform computer program ReSpect to infer the continuous and discrete relaxation spectra from dynamic moduli measurements obtained by small-angle oscillatory shear experiments. We employ nonlinear Tikhonov regularization and the Levenberg-Marquardt method to extract the continuous relaxation spectrum. To obtain the discrete relaxation spectrum, we introduce a novel algorithm that exploits the continuous spectrum to position the modes. It uses a simple criterion which balances accuracy and conditioning of the resulting least-squares problem to determine a parsimonious number of modes. The end result is an easy-to-use, and easy-to-extend program, which can be used from the command-line or from a graphical user interface to override some of the default algorithmic choices. © 2013 Applied Rheology.

Related Software ReSpect available for free download at mathworks.

Cite this publication as follows:
Takeh A, Shanbhag S: A Computer Program to Extract the Continuous and Discrete Relaxation Spectra from Dynamic Viscoelastic Measurements, Appl. Rheol. 23 (2013) 24628.

Roberto Cesar de Oliveira Romano, Caio Cesar Liberato, Marcelo Montini, Jorge Borges Gallo, Maria Alba Cincotto, Rafael Giuliano Pileggi
Evaluation of transition from fluid to elastic solid of cementitious pastes with bauxite residue using oscillation rheometry and isothermal calorimetry

Appl. Rheol. 23:2 (2013) 23830 (9 pages)

This work evaluates the impact of using bauxite residue (BR) as filler addition in cementitious compositions, during the early ages of transformation from the viscous fluid phase to an elastic solid. Chemical reaction and consolidation (physical phenomena of hardening) were also correlated. The chemical reaction rate was accompanied using isothermal calorimetry and the consolidation measured using oscillatory rheometry (quantifying the storage modulus - G' and relating with yield stress, σ0). The results show that BR accelerates the cement hydration reaction, but in pastes with pure cement, consolidation was faster, showing a distinct effect on the fluid-solid transition.

Cite this publication as follows:
Romano RCdO, Liberato CC, Montini M, Gallo JB, Cincotto MA, Pileggi RG: Evaluation of transition from fluid to elastic solid of cementitious pastes with bauxite residue using oscillation rheometry and isothermal calorimetry, Appl. Rheol. 23 (2013) 23830.

Selvin P. Thomas, S.K. De, I.A. Hussein
Impact of Aspect ratio of Carbon Nanotubes on shear and extensional Rheology of Polyethylene Nanocomposites

Appl. Rheol. 23:2 (2013) 23635 (10 pages)

This paper reports the results of studies on the effect of aspect ratio of multiwall carbon nanotubes (CNT) on the shear and extensional rheological behavior of low density polyethylene (LDPE) nanocomposites. Up to a CNT loading of 2 wt%, as used in the present study, the shear rheological data suggest no network formation in the nanocomposites, irrespective of the aspect ratio of the nano filler. Dynamic shear viscosity η' increases with increase in loading and aspect ratio of CNT. However, at low CNT loadings (0.1 wt%) and with CNT of high aspect ratio, h. for the nanocomposites is found to be lower than that of neat polymer. Steady shear rheology results show negative values for the normal stress for the high aspect ratio CNT which is believed to be due to the tumbling of CNT with high aspect ratio. Results of extensional viscosity measurements show that extent of strain hardening is dependent on the CNT aspect ratio and follows the order, high aspect ratio > medium aspect ratio > short aspect ratio, while the time of break follows the reverse order. The effect of aspect ratio on critical extensional stress becomes prominent only at the high aspect ratio, but the stress increases with the increase in CNT loading, irrespective of the aspect ratio.

Cite this publication as follows:
Thomas SP, De S, Hussein I: Impact of Aspect ratio of Carbon Nanotubes on shear and extensional Rheology of Polyethylene Nanocomposites, Appl. Rheol. 23 (2013) 23635.

Dingzheng Yang, Andrew Hrymak
Rheology of Aqueous Dispersions of Hydrogenated Castor Oil

Appl. Rheol. 23:2 (2013) 23622 (9 pages)

Three major hydrogenated castor oil crystal morphologies have been observed: fiber, rosette and irregular crystal. Due to the difficulty in obtaining samples with a single crystal morphology, rheological studies of suspensions containing mixtures of the three morphologies in an aqueous solution have been undertaken. The viscometry of dilute suspensions has shown that the magnitude of intrinsic viscosity is dominated by the fraction of a crystal morphology type, i.e. fiber > rosette > irregular crystal. A modified Farris model was fitted to the rheology data for mixtures of crystal morphology with interacting particles. A yield stress exists for concentrated suspensions followed by a shear thinning behavior with the increase of shear rate. A power-law relation has been found between yield stress and total particle volume fraction, and a constant exponent of 1.5 has been obtained regardless of crystal morphology.

Cite this publication as follows:
Yang D, Hrymak A: Rheology of Aqueous Dispersions of Hydrogenated Castor Oil , Appl. Rheol. 23 (2013) 23622.


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