Whither tube theory: From believing to measuring

Likhtman, Alexei E.

doi:10.1016/j.jnnfm.2008.11.008

Cited by 60 publications

(58 citation statements)

References 17 publications

(15 reference statements)

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“…Open questions include the following [5,[15][16][17][18][19][20][21][22][23][24][25]. Do chains that have been stretched by deformation freely retract in a Rouse-like manner and on Rouse-like time scales?…”

Section: Introduction a Fundamental Open Questions And The Phenommentioning

confidence: 99%

A force-level theory of the rheology of entangled rod and chain polymer liquids. I. Tube deformation, microscopic yielding, and the nonlinear elastic limit

Schweizer

Sussman

2016

The Journal of Chemical Physics

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We employ a first principles, force-level approach to self-consistently construct the anharmonic tube confinement field for entangled fluids of rigid needles and for primitive-path (PP) level chains in two limiting situations where chain stretching is assumed to either completely relax or remain unrelaxed. The influence of shear and extensional deformation and polymer orientation is determined in a nonlinear elastic limit where dissipative relaxation processes are intentionally neglected. For needles and PP-level chains, a Gaussian analysis of transverse polymer dynamical fluctuations predicts that deformation-induced orientation leads to tube dilation. In contrast, for deformed polymers in which chain stretch does not relax we find tube compression. For all three systems, a finite maximum transverse entanglement force localizing the polymers in effective tubes is predicted. The conditions when this entanglement force can be overcome (a force imbalance) by an externally applied force associated with macroscopic deformation can be crisply defined in the nonlinear elastic limit, and the possibility of a "microscopic absolute yielding" event destroying the tube confinement can be analyzed. For needles and contour-relaxed PP chains, this force imbalance is found to occur at a stress of order the equilibrium shear modulus and thus a strain of order unity, corresponding to a mechanically fragile entanglement tube field. However, for unrelaxed stretched chains, tube compression stabilizes transverse polymer confinement, and there appears to be no force imbalance. These results collectively suggest that the crossover from elastic to irreversible viscous response requires chain retraction to initiate disentanglement. We qualitatively discuss comparisons with existing phenomenological models for nonlinear startup shear, step strain, and creep rheology experiments.

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Section: Introduction a Fundamental Open Questions And The Phenommentioning

confidence: 99%

A force-level theory of the rheology of entangled rod and chain polymer liquids. I. Tube deformation, microscopic yielding, and the nonlinear elastic limit

Schweizer

Sussman

2016

The Journal of Chemical Physics

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“…6 Recent opinion pieces summarizing the state of understanding of entangled polymer dynamics have emphasized the need for a conceptual breakthrough, especially on the tube diameter scale and under strong deformation conditions. 7 In this Communication, we initiate the extension of our first-principles microscopic approach for entangled polymer dynamics 8,9 in a fluid of infinitely thin, non-rotating rigid rods of length L to treat the effect of applied stress. Our prior theory predicted the crossover to anisotropic diffusion and the full transverse confining field when the rod number density ρ (degree of entanglement) exceeds a critical threshold.…”

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confidence: 99%

Communication: Effects of stress on the tube confinement potential and dynamics of topologically entangled rod fluids

Sussman

Schweizer

2011

The Journal of Chemical Physics

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A microscopic theory for the effect of applied stress on the transverse topological confinement potential and slow dynamics of heavily entangled rigid rods is presented. The confining entanglement force localizing a polymer in a tube is predicted to have a finite strength. As a consequence, three regimes of terminal relaxation behavior are predicted with increasing stress: accelerated reptation due to tube widening (dilation), relaxation via deformation-assisted activated transverse barrier hopping, and complete destruction of the lateral tube constraints corresponding to microscopic yielding or a disentanglement transition.

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“…The effect of cross-correlation between different chains in entangled polymers has been reported [1][2][3] and its contribution to rheology is not negligible [4][5][6] . In the tube model 7) and its extensions 8,9) , the test chain is assumed to move independently and the cross-correlation is not considered, at least explicitly.…”

Section: Introductionmentioning

confidence: 99%

“…There have been several reports in which the inter-chain correlations are attributed to the nematic-type interactions 5,10) .…”

Section: Introductionmentioning

confidence: 99%

Inter-Chain Cross-Correlation in Multi-Chain Slip-Link Simulations without Force Balance at Entanglements

Masubuchi

Pandey

Amamoto

2017

J. Soc. Rheol., Jpn

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For entangled polymers, there exist considerable contributions of the cross-correlation between different chains in the relaxation modulus, though the contribution is neglected in the single-chain models. Earlier studies have suggested that the cross-correlation is due to the inter-chain interactions such as the force balance around entanglements and the osmotic force suppressing the density fluctuations. However, the origin of the cross-correlation has been yet to be clarified. In this study, a new multi-chain slip-link model has been developed for the simulations of polymer dynamics without the inter-chain forces while the creation of entanglement is performed according to the geometrical manner and the local equilibration. The simulations reproduced the qualitative features of entangled polymer dynamics for the molecular weight dependence of the longest relaxation time and the diffusion coefficient, just as expected from the success of the earlier single-chain models without the inter-chain forces. On the other hand, the remarkable feature of the model is that the cross-correlation exists between chains, suggesting that the cross-correlation is generated via the local equilibration at the creation of entanglement even without the global equilibration by the inter-chain forces.

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Whither tube theory: From believing to measuring

Cited by 60 publications

References 17 publications

A force-level theory of the rheology of entangled rod and chain polymer liquids. I. Tube deformation, microscopic yielding, and the nonlinear elastic limit

A force-level theory of the rheology of entangled rod and chain polymer liquids. I. Tube deformation, microscopic yielding, and the nonlinear elastic limit

Communication: Effects of stress on the tube confinement potential and dynamics of topologically entangled rod fluids

Inter-Chain Cross-Correlation in Multi-Chain Slip-Link Simulations without Force Balance at Entanglements

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