“Butterfly” Light Scattering Pattern in Shear-Enhanced   Concentration Fluctuations in Polymer Solutions   and Anomaly at High Shear Rates

Hashimoto, Takeji; Kume, Takuji

doi:10.1143/jpsj.61.1839

Cited by 96 publications

(141 citation statements)

References 18 publications

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“…This suggests that shear enhances the growth in the velocity direction but suppresses it in the gradient direction. This seems to be confirmed by experiments [21,32,33,52].…”

Section: Introductionsupporting

confidence: 62%

Simulations of phase separation in quiescent and sheared liquids

Thakre¹

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“…This suggests that shear enhances the growth in the velocity direction but suppresses it in the gradient direction. This seems to be confirmed by experiments [21,32,33,52].…”

Section: Introductionsupporting

confidence: 62%

Simulations of phase separation in quiescent and sheared liquids

Thakre¹

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“…(Figure 1b, 2a, and 3b in row (B)). [19,22] -Regime III where _ g c;z < _ g < _ g a or t c2 < t < t c3, and _ g a approximately corresponds to t À1 e where t e is the rheological relaxation time for chain stretching. The scattering along the neutral axis starts to remarkably increase (Figure 1b and 2a), which may be a signature of a transformation from the shear-enhanced plane-wave type concentration fluctuations to shear-induced demixed structures.…”

Section: Resultsmentioning

confidence: 99%

“…[15,17,26,27] Rheology exhibits the shear thinning in Regime II and III (Figure 1a). [18,19,21,[28][29][30] The sheared solutions show almost no birefringence up to Regime III ( Figure 1a, 2b), indicating that polymer chains are essentially in relaxed random coils even under the shear flow.…”

Section: Resultsmentioning

confidence: 99%

“…to the flow direction; part c presents isointensity contour plots of the scattering patterns. The steady-state behaviors of these properties are classified into four regimes (Regime I to IV) as shown in part a with respect to three characteristic shear rates _ g c;x , _ g c;z , and _ g a [1,19] as will be defined later in conjunction with Figure 3. Figure 2 typically shows time evolution of the normalized integrated scattered intensity parallel (//) and perpendicular (?)…”

Section: Experimental Partmentioning

confidence: 99%

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Shear‐Induced Phase Separation of Entangled Polymer Solutions: Formation of Optically Anisotropic Strings as Precursor Structures of Shish‐Kebab

Hashimoto

Murase

Ohta

2009

Macromolecular Symposia

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Summary: Shear-induced structures were investigated for both ultrahigh molecular weight atactic polystyrene (UHMWaPS) and linear polyethylene (UHMWPE) solutions, which were entangled but homogeneous without shear flow, as a function of shear rate ( _ g) or time after a step-up shear flow. For the PE solutions, the shear flow was imposed at 124 8C which is higher than the nominal melting temperature T nm of the solution without shear flow. At sufficiently high shear rates both solutions commonly formed highly optically anisotropic string-like structures which are composed of a series of phase-separated domains interconnected by bundles of stretched chains and aligned along the flow direction. After cessation of the shear flow the string-like structures completely disappeared in the UHMWaPS solution, recovering a homogeneous solution, while the UHMWPE solution exhibited shish-kebab structure. The results reveal a new kinetic pathway for shish-kebab formation for the entangled crystallizable solution sheared at T > T nm which involves first formation of the phaseseparated string-like domains and subsequent crystallization into shish from the bundles of stretched chain and then kebab in the demixed domains composed of essentially random coils.

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“…This seems to be confirmed by experiments. [5][6][7][8] Different time scales are involved in the breakup and coalescence of a domain. Depending on the ratio between these time scales and the deformation time scale of the flow, different metastable states are observed.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of phase separating binary liquids in cylindrical Couette flow

Thakre

Padding

Otter

et al. 2008

The Journal of Chemical Physics

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Related ArticlesStructure and dynamics of 1,2-dimethoxyethane and 1,2-dimethoxypropane in aqueous and non-aqueous solutions: A molecular dynamics study J. Chem. Phys. 135, 164501 (2011) Origin of large Landau-Placzek ratio in a liquid metallic alloy J. Chem. Phys. 135, 154510 (2011) Orientational and translational correlations of liquid methane over the nanometer-picosecond scales by molecular dynamics simulation and inelastic neutron scattering J. Chem. Phys We use molecular dynamics simulations to study phase separation of a 50:50 ͑by volume͒ fluid mixture in a confined and curved ͑Taylor-Couette͒ geometry, consisting of two concentric cylinders. The inner cylinder may be rotated to achieve a shear flow. In nonsheared systems we observe that, for all cases under consideration, the final equilibrium state has a stacked structure. Depending on the lowest free energy in the geometry the stack may be either flat, with its normal in the z direction, or curved, with its normal in the r or direction. In sheared systems we make several observations. First, when starting from a prearranged stacked structure, we find that sheared gradient and vorticity stacks retain their character for the durations of the simulation, even when another configuration is preferred ͑as found when starting from a randomly mixed configuration͒. This slow transition to another configuration is attributed to a large free energy barrier between the two states. In case of stacks with a normal in the gra...

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“Butterfly” Light Scattering Pattern in Shear-Enhanced Concentration Fluctuations in Polymer Solutions and Anomaly at High Shear Rates

Cited by 96 publications

References 18 publications

Simulations of phase separation in quiescent and sheared liquids

Simulations of phase separation in quiescent and sheared liquids

Shear‐Induced Phase Separation of Entangled Polymer Solutions: Formation of Optically Anisotropic Strings as Precursor Structures of Shish‐Kebab

Molecular dynamics simulation of phase separating binary liquids in cylindrical Couette flow

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