Hierarchical Approach to Flow Calculations for Polymeric Liquid Crystals

Laso, Manuel; Muneta, L. M.; Müller, Manfred; Alcázar, Victoria; Chinesta, Francisco; Animar, A.

doi:10.1016/s1570-7946(06)80017-9

Cited by 2 publications

(1 citation statement)

References 42 publications

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“…The success of the model suggested that the non-aggregating CNTs behave essentially as short rigid fibres and the corresponding shear-thinning behaviour was due to the progressive alignment of CNT in the shear direction. In reference [94], the degree of alignment was quantified using a scalar order parameter S commonly used in liquid crystal (polymer) studies [60,130]. S varies between 0 and 1 and the larger the magnitude of S, the higher the degree of alignment.…”

Section: Modellingmentioning

confidence: 99%

A review of the microstructure and rheology of carbon nanotube suspensions

Yearsley

Chinesta

et al. 2008

Proceedings of the Institution of Mechanical Engineers, Part N:

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The present review is concerned with the way that the incorporation of carbon nanotubes (CNTs) into a fluid matrix can modify the microstructure and rheology of the resulting suspensions. Some background to CNT manufacture and in particular methods of dispersing them into a suspension is presented for a range of different systems, where effective dispersion of CNTs remains a delicate and open issue. Steady shear, linear viscoelasticity, non-linear viscoelasticity and extensional responses are classified for a range of different CNT/matrix combinations together with their associated microstructure. The rheological modelling of certain CNT/matrix systems is reviewed, with particular attention given to the authors' work on modelling CNT suspension behaviour using Fokker-Planck advection-diffusion modelling.

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Section: Modellingmentioning

confidence: 99%

A review of the microstructure and rheology of carbon nanotube suspensions

Yearsley

Chinesta

et al. 2008

Proceedings of the Institution of Mechanical Engineers, Part N:

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The rheology and modeling of chemically treated carbon nanotubes suspensions

Ma¹,

Chinesta²,

Mackley³

2009

Journal of Rheology

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This paper reports recent experimental findings and rheological modeling on chemically treated single-walled carbon nanotubes ͑CNTs͒ suspended within an epoxy resin. When a CNT suspension was subject to a steady shear flow, it exhibited a shear-thinning characteristic, which was subsequently modeled by a Fokker-Planck ͑FP͒ based orientation model. The model assumes that the shear flow aligns CNT in the flow direction, but there are events such as Brownian motion and tube-tube interaction trying to randomize the orientation. In the FP orientation model, randomizing events were modeled with an appropriate rotary diffusion coefficient ͑D r ͒ and the shear-thinning behavior was explained in terms of progressive alignment of CNTs toward the shear direction. In terms of linear viscoelasticity ͑LVE͒, small-amplitude oscillatory measurements revealed mild elasticity for semidilute treated CNT suspensions. The exact origin for this elasticity is not clear and both tube-tube interaction and bending/stretching of CNTs have been proposed by other authors as possible origins. It is, however, clear from the current modeling that the experimental evolution of storage modulus ͑GЈ͒ cannot be described using a single-mode Maxwell model or simple Brownian rod modeling. In this paper, experimental LVE data of the treated CNT suspensions were fitted using the FP orientation model with an "effective diffusion coefficient" term and an empirical relation was subsequently identified for the effective diffusion term. Intuitively, chemical treatment has created a weakly interconnected network of CNT and it is believed that the mild elasticity originated from this weak network as well as other randomizing events ͑Brownian motion and tube-tube hydrodynamic interaction͒. Finally, step strain experiments confirmed the presence of a weak network at small strains, which at large strains was found to be destroyed. Incorporation of a strain softening factor allowed for the formulation of a 1 self-consistent FP based orientation model describing both the steady shear and LVE responses of treated CNT suspensions.

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Hierarchical Approach to Flow Calculations for Polymeric Liquid Crystals

Cited by 2 publications

References 42 publications

A review of the microstructure and rheology of carbon nanotube suspensions

A review of the microstructure and rheology of carbon nanotube suspensions

The rheology and modeling of chemically treated carbon nanotubes suspensions

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