Detailed analysis of Rouse mode and dynamic scattering function of highly entangled polymer melts in equilibrium

We present large-scale molecular dynamics simulations for a coarse-grained model of polymer melts in equilibrium. From detailed Rouse mode analysis we show that the time-dependent relaxation of the autocorrelation function (ACF) of modes p can be well described by the effective stretched exponential...

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Bibliographic Details
Published in:The European physical journal. ST, Special topics Special topics, 2017-04, Vol.226 (4), p.693-703
Main Authors: Hsu, Hsiao-Ping, Kremer, Kurt
Format: Article
Language:English
Subjects:
Atomic
Autocorrelation functions
Chain entanglement
Classical and Continuum Physics
Condensed Matter Physics
Crossovers
Entanglement
Exponential functions
Materials Science
Measurement Science and Instrumentation
Melts
Molecular
Molecular dynamics
Monomers
Optical and Plasma Physics
Physics
Physics and Astronomy
Polymer melts
Polymers
Recent Advances in Phase Transitions and Critical Phenomena
Regular Article
Relaxation time
Reptation
Scattering functions
Time dependence
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Summary:We present large-scale molecular dynamics simulations for a coarse-grained model of polymer melts in equilibrium. From detailed Rouse mode analysis we show that the time-dependent relaxation of the autocorrelation function (ACF) of modes p can be well described by the effective stretched exponential function due to the crossover from Rouse to reptation regime. The ACF is independent of chain sizes N for N / p < N e ( N e is the entanglement length), and there exists a minimum of the stretching exponent as N / p → N e . As N / p increases, we verify the crossover scaling behavior of the effective relaxation time τ eff, p from the Rouse regime to the reptation regime. We have also provided evidence that the incoherent dynamic scattering function follows the same crossover scaling behavior of the mean square displacement of monomers at the corresponding characteristic time scales. The decay of the coherent dynamic scattering function is slowed down and a plateau develops as chain sizes increase at the intermediate time and wave length scales. The tube diameter extracted from the coherent dynamic scattering function is equivalent to the previous estimate from the mean square displacement of monomers.
ISSN:1951-6355
1951-6401
DOI:10.1140/epjst/e2016-60322-5