Rheology: From simple and to complex fluids

Hess, Siegfried; Aust, C.; Bennett, Loris; Kröger, Martin; Borgmeyer, C. Pereira; Weider, T.

doi:10.1016/s0378-4371(97)00136-2

Cited by 36 publications

(39 citation statements)

References 71 publications

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“…In Fig.3 we can see that the dynamics of our system cannot be described by the Rouse dynamics with increasing N ( 100). Though the largest N (= 250) is only 2.5 times larger than our estimated N e , the N dependencies in Fig.3 are consistent with the crossover from the Rouse to reptation dynamics reported in the previous simulations [10][11][12][13][15][16][17]. We also show that our model polymer melts exhibit strongly nonlinear behavior forγ > τ −1 r .…”

Section: B Crossover From Rouse To Reptation Dynamicssupporting

confidence: 91%

“…At this temperature there was no glass-like enhancement of the structural relaxation time, but at T = 0.2ǫ/k B the present model with N = 10 became glassy in our previous simulation [24]. Note that our density value is higher than the widely used value n = 0.85/σ 3 in the previous simulations [10,13,[15][16][17][18]25] (With increasing n the free volume for particles decreases and hence N e in our case should be somewhat shorter than in the previous simulations). The consecutive beads on each chain are connected by an anharmonic spring potential of the form,…”

Section: A Modelmentioning

confidence: 50%

“…The reptation theory [2][3][4][5][6][7] is the most successful approach to date in describing the dynamics of entangled polymer chains in a surprisingly simple manner. It has been supported by a number of experimental [8,9] and numerical [10][11][12][13][14][15][16][17][18][19][20] papers, where experimentally accessible quantities such as the stress relaxation function G(t), the incoherent dynamic scattering function, the mean square displacement, and the viscosity have been compared with the theoretical predictions [3]. However, N e estimated from the mean square displacement and that from the plateau modulus were around 30 and 70, respectively [13], where the difference of these two estimations indicates inaccuracy of the prefactors in the predicted formulae [3,21].…”

Section: Introductionmentioning

confidence: 81%

“…See Refs. [15,16,24] for the microscopic expression of σ αβ (t). On one hand, the curve for the short chain case N = 25 and M = 40 is a result of the averages over 10 independent runs and over the initial time t 0 .…”

Section: B Crossover From Rouse To Reptation Dynamicsmentioning

confidence: 99%

“…Though still inadequate, extensive simulations have been performed in this direction [15][16][17][18][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Entanglements in quiescent and sheared polymer melts

Yamamoto

Ōnuki

2004

Phys. Rev. E

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We visualize entanglements in polymer melts using molecular dynamics simulation. A bead at an entanglement interacts persistently for long times with the non-bonded beads (those excluding the adjacent ones in the same chain). The interaction energy of each bead with the non-bonded beads is averaged over a time interval τ much longer than microscopic times but shorter than the onset time of tube constraints τe. Entanglements can then be detected as hot spots consisting of several beads with relatively large values of the time-averaged interaction energy. We next apply a shear flow with rate much faster than the entangle motion. With increasing strain the chains take zigzag shapes and a half of the hot spots become bent. The chains are first stretched as a network but, as the bends approach the chain ends, disentanglements subsequently occur, leading to stress overshoot observed experimentally.

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Section: B Crossover From Rouse To Reptation Dynamicssupporting

confidence: 91%

Section: A Modelmentioning

confidence: 50%

Section: Introductionmentioning

confidence: 81%

Section: B Crossover From Rouse To Reptation Dynamicsmentioning

confidence: 99%

“…Though still inadequate, extensive simulations have been performed in this direction [15][16][17][18][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Entanglements in quiescent and sheared polymer melts

Yamamoto

Ōnuki

2004

Phys. Rev. E

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Block Copolymers Under Shear Flow

Rychkov

2005

Macro Theory & Simulations

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Summary: Microphase separation transition in block copolymer melts and solutions in equilibrium and under shear flow is reviewed. The non‐equilibrium molecular dynamics (NEMD) computer simulation methodology is presented in detail including the derivation of the SLLOD equations of motion, Gaussian thermostat, and operator‐splitting symplectic integrators. Results of our recent NEMD computer simulation studies of diblock copolymers in a selective solvent under shear flow are presented. Shear‐dependent structural, rheological, and microscopical properties are described. New phase transitions are discovered. The parallel‐perpendicular orientational transition in a weak‐strong flow is revealed. Theoretical approaches are reviewed including the Edwards Hamiltonian, Landau‐Ginzburg model, self‐consistent mean field theory, field‐theoretic simulation, as well as the time‐dependent Landau‐Ginzburg framework and its application to the studies of complex fluids. magnified image

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Nano‐Rheology of Single Unentangled Polymeric Lubricant Films

Guo

Chung

Jhon

et al. 2008

Macro Theory & Simulations

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Rheology and tribology become more and more critical issues in order to satisfy the harsh requirements for ultra‐small head/media spacing HDDs. In this communication, MD simulations with a bead/spring model were employed to examine the nano‐rheological response of nonfunctional and functional PFPEs by analyzing the shear viscosity of nanoscale PFPE films and the relaxation processes as a function of wall interaction/separation and endgroup functionality. Our simulation results indicate that thin PFPE films show more solid‐like behavior, especially under high shear rate. The film deformation and shear viscosity change by tuning the film thickness and the endgroup functionality was discussed in conjunction with the relaxation processes.

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Rheology: From simple and to complex fluids

Cited by 36 publications

References 71 publications

Entanglements in quiescent and sheared polymer melts

Entanglements in quiescent and sheared polymer melts

Block Copolymers Under Shear Flow

Nano‐Rheology of Single Unentangled Polymeric Lubricant Films

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