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Erschienen in: Rheologica Acta 2/2008

01.03.2008 | Original Contribution

Effects of strong anchoring on the dynamic moduli of heterogeneous nematic polymers

verfasst von: Eric P. Choate, Zhenlu Cui, M. Gregory Forest

Erschienen in: Rheologica Acta | Ausgabe 2/2008

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Abstract

We focus on the linear viscoelastic response of heterogeneous nematic polymers to small amplitude oscillatory shear, paying special attention to the macroscopic influence of strong plate anchoring conditions. The model consists of the Stokes hydrodynamic equations with viscous and nematic stresses, coupled to orientational dynamics and structure driven by the flow gradient, an excluded-volume potential, and a two-constant distortional elasticity potential. We show that the dynamical response simplifies when plate anchoring is either tangential or homeotropic, recovering explicitly solvable Leslie–Ericksen–Frank behavior together with weakly varying order parameters across the plate gap. With these plate conditions, we establish “model consistency” so that all experimental driving conditions (plate-controlled velocity [strain] or shear stress, imposed oscillatory pressure) yield identical dynamic moduli for the same material parameters and anchoring conditions, eliminating the culpability of device influence in scaling behavior. Two physical predictions emerge that imply significant macroscopic elastic and viscous effects controlled by plate anchoring relative to flow geometry: (1) The storage modulus is enhanced by two to three orders of magnitude for homeotropic relative to parallel anchoring, across all frequencies. (2) The loss modulus exhibits enhancement of a factor of two to three for homeotropic over tangential anchoring, restricted to low frequencies. We further deduce a scaling law for the dynamic moduli versus anisotropy of the distortional elasticity potential.

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1
As also observed in (de Andrade Lima and Rey 2004b), when l L = 1, we find purely viscous behavior for tangential anchoring with (w) = 0 and G″(w) = C w.
 
Literatur
Zurück zum Zitat Burghardt WR (1991) Oscillatory shear flow of nematic liquid crystals. J Rheol 35:49–62CrossRef Burghardt WR (1991) Oscillatory shear flow of nematic liquid crystals. J Rheol 35:49–62CrossRef
Zurück zum Zitat Choate EP, Forest MG (2006) A classical problem revisited: Rheology of nematic polymer monodomains in small amplitude oscillatory shear. Rheol Acta 46:83–94CrossRef Choate EP, Forest MG (2006) A classical problem revisited: Rheology of nematic polymer monodomains in small amplitude oscillatory shear. Rheol Acta 46:83–94CrossRef
Zurück zum Zitat Colby RH, Nentwich LM, Clingman SR, Ober CK (2002) Defect-mediated creep of structured materials. Europhys Lett 54:269–274CrossRef Colby RH, Nentwich LM, Clingman SR, Ober CK (2002) Defect-mediated creep of structured materials. Europhys Lett 54:269–274CrossRef
Zurück zum Zitat Cui Z, Forest MG, Wang Q, Zhou H (2006) On weak plane shear and Poiseuille flows of rigid rod and platelet ensembles. SIAM J Appl Math 66:1227–1260CrossRef Cui Z, Forest MG, Wang Q, Zhou H (2006) On weak plane shear and Poiseuille flows of rigid rod and platelet ensembles. SIAM J Appl Math 66:1227–1260CrossRef
Zurück zum Zitat de Andrade Lima LRP, Rey AD (2004a) Superposition and universality in the linear viscoelasticity of Leslie–Ericken liquid crystals. J Rheol 48:1067–1084CrossRef de Andrade Lima LRP, Rey AD (2004a) Superposition and universality in the linear viscoelasticity of Leslie–Ericken liquid crystals. J Rheol 48:1067–1084CrossRef
Zurück zum Zitat de Andrade Lima LRP, Rey AD (2004b) Assessing flow alignment of nematic liquid crystals through linear viscoelasticity. Phys Rev E 70:011701CrossRef de Andrade Lima LRP, Rey AD (2004b) Assessing flow alignment of nematic liquid crystals through linear viscoelasticity. Phys Rev E 70:011701CrossRef
Zurück zum Zitat de Andrade Lima LRP, Rey AD (2006) Superposition principles for small amplitude oscillatory shearing of nematic mesophases. Rheol Acta 45:591–600CrossRef de Andrade Lima LRP, Rey AD (2006) Superposition principles for small amplitude oscillatory shearing of nematic mesophases. Rheol Acta 45:591–600CrossRef
Zurück zum Zitat Forest MG, Wang Q (2003) Monodomain response of finite-aspect-ratio macromolecules in shear and related linear flows. Rheol Acta 42:20–46CrossRef Forest MG, Wang Q (2003) Monodomain response of finite-aspect-ratio macromolecules in shear and related linear flows. Rheol Acta 42:20–46CrossRef
Zurück zum Zitat Forest MG, Wang Q, Zhou H (2000) Exact banded patterns from a Doi–Marrucci–Greco model of nematic liquid crystal polymers. Phys Rev E 61:6655–6662CrossRef Forest MG, Wang Q, Zhou H (2000) Exact banded patterns from a Doi–Marrucci–Greco model of nematic liquid crystal polymers. Phys Rev E 61:6655–6662CrossRef
Zurück zum Zitat Forest MG, Wang Q, Zhou H, Zhou R (2004) Structure scaling properties of confined nematic polymers in plane shear cells: the weak flow limit. J Rheol 48:175–192CrossRef Forest MG, Wang Q, Zhou H, Zhou R (2004) Structure scaling properties of confined nematic polymers in plane shear cells: the weak flow limit. J Rheol 48:175–192CrossRef
Zurück zum Zitat Larson RG, Mead DW (1989) Linear viscoelasticity of nematic liquid crystalline polymers. J Rheol 33:185–206CrossRef Larson RG, Mead DW (1989) Linear viscoelasticity of nematic liquid crystalline polymers. J Rheol 33:185–206CrossRef
Zurück zum Zitat Mather PT, Romo-Uribe A, Han CD, Kim SS (1997) Rheo-optical evidence of a flow-induced isotropic–nematic transition in a thermotropic liquid-crystalline polymer. Macromolecules 30:7977–7989CrossRef Mather PT, Romo-Uribe A, Han CD, Kim SS (1997) Rheo-optical evidence of a flow-induced isotropic–nematic transition in a thermotropic liquid-crystalline polymer. Macromolecules 30:7977–7989CrossRef
Zurück zum Zitat Mendil H, Baroni P, Noirez L (2005) Unexpected giant elasticity in side-chain liquid–crystal polymer melts: A new approach for the understanding of shear-induced phase transition. Europhys Lett 76:983–989CrossRef Mendil H, Baroni P, Noirez L (2005) Unexpected giant elasticity in side-chain liquid–crystal polymer melts: A new approach for the understanding of shear-induced phase transition. Europhys Lett 76:983–989CrossRef
Zurück zum Zitat Mendil H, Baroni P, Noirez L (2006) Solid-like rheological response of non-entangled polymers in the molten state. Euro Phys J E 19:77–85CrossRef Mendil H, Baroni P, Noirez L (2006) Solid-like rheological response of non-entangled polymers in the molten state. Euro Phys J E 19:77–85CrossRef
Zurück zum Zitat Pujolle-Robic C, Noirez L (2001) Observation of shear-induced nematic–isotropic transition in side-chain liquid crystal polymers. Nature 409:167–171CrossRef Pujolle-Robic C, Noirez L (2001) Observation of shear-induced nematic–isotropic transition in side-chain liquid crystal polymers. Nature 409:167–171CrossRef
Zurück zum Zitat Rubin SF, Kannan RM, Kornfield JA, Boeffel C (1995) Effect of mesophase order and molecular weight on the dynamics of nematic and smectic side-group liquid-crystalline polymers. Macromolecules 28:3521–3530CrossRef Rubin SF, Kannan RM, Kornfield JA, Boeffel C (1995) Effect of mesophase order and molecular weight on the dynamics of nematic and smectic side-group liquid-crystalline polymers. Macromolecules 28:3521–3530CrossRef
Zurück zum Zitat Wang Q (2002) A hydrodynamic theory of nematic liquid crystalline polymers of different configurations. J Chem Phys 116:9120–9136CrossRef Wang Q (2002) A hydrodynamic theory of nematic liquid crystalline polymers of different configurations. J Chem Phys 116:9120–9136CrossRef
Zurück zum Zitat Zhou H, Forest MG (2006) Anchoring distortions coupled with plane Couette and Poiseuille flows of nematic polymers in viscous solvents: morphology in molecular orientation, stress, and flow. Discrete Contin Dyn Syst B 6:407–425 Zhou H, Forest MG (2006) Anchoring distortions coupled with plane Couette and Poiseuille flows of nematic polymers in viscous solvents: morphology in molecular orientation, stress, and flow. Discrete Contin Dyn Syst B 6:407–425
Zurück zum Zitat Zhou H, Forest MG (2007) Nematic liquids in weak capillary Poiseuille flow: Structure scaling laws and effective conductivity implications. International J Numer Anal Mod 4:460–477 Zhou H, Forest MG (2007) Nematic liquids in weak capillary Poiseuille flow: Structure scaling laws and effective conductivity implications. International J Numer Anal Mod 4:460–477
Metadaten
Titel
Effects of strong anchoring on the dynamic moduli of heterogeneous nematic polymers
verfasst von
Eric P. Choate
Zhenlu Cui
M. Gregory Forest
Publikationsdatum
01.03.2008
Verlag
Springer-Verlag
Erschienen in
Rheologica Acta / Ausgabe 2/2008
Print ISSN: 0035-4511
Elektronische ISSN: 1435-1528
DOI
https://doi.org/10.1007/s00397-007-0235-2

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