Linear macroscopic properties of polymeric liquids and melts. A new approach

Brand, Helmut R.; Pleiner, Harald; Renz, Wolfgang

doi:10.1051/jphys:0199000510110106500

Cited by 23 publications

(13 citation statements)

References 10 publications

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“…In these cases the system reacts like a fluid below a certain frequency, the so-called Maxwell frequency, and like a solid or glass above this frequency. Therefore, the consequences of a transient strain field on the macroscopic behavior by combining it with the hydrodynamic approach have also been explored [60][61][62][63][64][65]. It therefore seems a natural next step to incorporate macroscopic variables such as a transient strain field into the EDDFT approach.…”

Section: Discussionmentioning

confidence: 99%

Microscopic approach to entropy production

Wittkowski¹,

Löwen²,

Brand³

2013

J. Phys. A: Math. Theor.

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It is a great challenge of nonequilibrium statistical mechanics to calculate entropy production within a microscopic theory. In the framework of linear irreversible thermodynamics, we combine the Mori-Zwanzig-Forster projection operator technique with the first and second law of thermodynamics to obtain microscopic expressions for the entropy production as well as for the transport equations of the entropy density and its time correlation function. We further present a microscopic derivation of a dissipation functional from which the dissipative dynamics of an extended dynamical density functional theory can be obtained in a formally elegant way.

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Section: Discussionmentioning

confidence: 99%

Microscopic approach to entropy production

Wittkowski¹,

Löwen²,

Brand³

2013

J. Phys. A: Math. Theor.

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“…The dynamic couplings between polarization and heat and concentration current, provided by the dissipative transport parameters D P ⊥,|| and κ P ⊥,|| , Eqs. (31) and (32) are specific to polar nematics. In such materials a (transverse) heat current is invoked by a rotation ofp i , if an external field is present, j σ ⊥ ∼ −2κ P ⊥ χE 2 δp ⊥ , while changes in the magnitude of the polarization and of the temperature, pressure, or concentra-tion all lead to a longitudinal heat current j σ || ∼ −κ P || χ −1 δP , ∼ δρ, ∼ δT , ∼ δc, respectively.…”

Section: Experimental Consequencesmentioning

confidence: 99%

“…The use of macroscopic variables has been pioneered by Khalatnikov [26] using the modulus of the order parameter as a macroscopic variable in the vicinity of the λ transition in superfluid 4 He. This concept has since been applied to numerous systems including the superfluid phases of 3 He [27] (for which the tiny magnetic dipole interaction renders the magnetization density to be no longer strictly hydrodynamic) and to nematic elastomers [28,29] and uniaxial magnetic gels [30] (for which relative rotations between the polymer network and the director or the magnetization become macroscopically important) as well as to polymers [31] and nematic side-chain polymers [32] for which the strain associated with the transient network becomes a macroscopic variable.…”

Section: Introductionmentioning

confidence: 99%

Macroscopic dynamics of polar nematic liquid crystals

2006

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We present the macroscopic equations for polar nematic liquid crystals. We consider the case where one has both, the usual nematic director, n[over ] , characterizing quadrupolar order as well as the macroscopic polarization, P , representing polar order, but where their directions coincide and are rigidly coupled. In this case one has to choose P as the independent macroscopic variable. Such equations are expected to be relevant in connection with nematic phases with unusual properties found recently in compounds composed of banana-shaped molecules. Among the effects predicted, which are absent in conventional nematic liquid crystals showing only quadrupolar order, are pyro-electricity and its analogs for density and for concentration in mixtures as well as a flow alignment behavior, which is more complex than in usual low molecular weight nematics. We also discuss the formation of defect structures expected in such systems.

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“…In case of a transient elasticity, this strain field relaxes on the long time scale. The consequences of the approach of transient elasticity for complex fluids such as polymer solutions and melts have been investigated in the linear [29,30] as well as in the nonlinear regime [31][32][33][34][35][36][37] for systems ranging from polymer melts and solutions [29, 31-34, 36, 37] over nematic polymers [30,35] to ferrocholesteric gels and elastomers [38]. Quite recently the applicability of the theory of transient elasticity to a large range of rheologically important small and large amplitude experiments has also been demonstrated [39,40].…”

Section: Macroscopic Dynamicsmentioning

confidence: 99%

On the influence of a network on optically isotropic fluid phases with tetrahedral/octupolar order

Brand

Pleiner

2017

Eur. Phys. J. E

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Abstract.We investigate the influence of transient or permanent elasticity on liquid phases with octupolar (tetrahedral) order, a question that has never been addressed before. The focus will be on optically isotropic liquid phases with tetrahedral order including the T d phase and the chiral T phase introduced by Fel. It turns out that the presence of both, a network as well as tetrahedral order can lead to the formation of chiral domains of both hands in an optically isotropic fluid due to a completely novel mechanism, thus providing a possible macroscopic explanation for recent experimental observations. We study in detail how elasticity influences the macroscopic dynamics of both, the T d and the T phase. The simultaneous presence of a transient network as well as of octupolar order is shown to lead to completely new crosscoupling phenomena for optically isotropic systems including transient dissipative elastic strains due to temperature gradients.

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Linear macroscopic properties of polymeric liquids and melts. A new approach

Abstract: Abstract. 2014

Cited by 23 publications

References 10 publications

Microscopic approach to entropy production

Microscopic approach to entropy production

Macroscopic dynamics of polar nematic liquid crystals

On the influence of a network on optically isotropic fluid phases with tetrahedral/octupolar order

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