scholarly journals Influence of Branching on the Configurational and Dynamical Properties of Entangled Polymer Melts

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1045 ◽  
Author(s):  
Alexandros Chremos ◽  
Jack F. Douglas
Keyword(s):  
Correlation Function ◽  
Molecular Mass ◽  
Polymer Melts ◽  
Pair Correlation ◽  
Polymer Melt ◽  
Coarse Grained ◽  
Density Correlation ◽  
Glass Forming ◽  
Entangled Polymer ◽  
Simulation Results

We probe the influence of branching on the configurational, packing, and density correlation function properties of polymer melts of linear and star polymers, with emphasis on molecular masses larger than the entanglement molecular mass of linear chains. In particular, we calculate the conformational properties of these polymers, such as the hydrodynamic radius R h , packing length p, pair correlation function g ( r ) , and polymer center of mass self-diffusion coefficient, D, with the use of coarse-grained molecular dynamics simulations. Our simulation results reproduce the phenomenology of simulated linear and branched polymers, and we attempt to understand our observations based on a combination of hydrodynamic and thermodynamic modeling. We introduce a model of “entanglement” phenomenon in high molecular mass polymers that assumes polymers can viewed in a coarse-grained sense as “soft” particles and, correspondingly, we model the emergence of heterogeneous dynamics in polymeric glass-forming liquids to occur in a fashion similar to glass-forming liquids in which the molecules have soft repulsive interactions. Based on this novel perspective of polymer melt dynamics, we propose a functional form for D that can describe our simulation results for both star and linear polymers, covering both the unentangled to entangled polymer melt regimes.

scholarly journals Quantitative relations between cooperative motion, emergent elasticity, and free volume in model glass-forming polymer materials

2015 ◽  
Vol 112 (10) ◽  
pp. 2966-2971 ◽  
Author(s):  
Beatriz A. Pazmiño Betancourt ◽  
Paul Z. Hanakata ◽  
Francis W. Starr ◽  
Jack F. Douglas
Keyword(s):  
Free Volume ◽  
Glass Formation ◽  
Collective Motion ◽  
Configurational Entropy ◽  
Polymer Melt ◽  
Polymer Materials ◽  
Coarse Grained ◽  
Glass Forming ◽  
Cooperative Motion ◽  
Glass Forming Materials

The study of glass formation is largely framed by semiempirical models that emphasize the importance of progressively growing cooperative motion accompanying the drop in fluid configurational entropy, emergent elasticity, or the vanishing of accessible free volume available for molecular motion in cooled liquids. We investigate the extent to which these descriptions are related through computations on a model coarse-grained polymer melt, with and without nanoparticle additives, and for supported polymer films with smooth or rough surfaces, allowing for substantial variation of the glass transition temperature and the fragility of glass formation. We find quantitative relations between emergent elasticity, the average local volume accessible for particle motion, and the growth of collective motion in cooled liquids. Surprisingly, we find that each of these models of glass formation can equally well describe the relaxation data for all of the systems that we simulate. In this way, we uncover some unity in our understanding of glass-forming materials from perspectives formerly considered as distinct.

The two-dimensional pair correlation function for the Si(001) surface: computer simulation results

1994 ◽  
Vol 6 (6) ◽  
pp. 1083-1088 ◽  
Author(s):  
Jia Zhengming ◽  
Yang Genqing ◽  
Cheng Zhaonian ◽  
Liu Xianghuai ◽  
Zou Shichang
Keyword(s):  
Computer Simulation ◽  
Correlation Function ◽  
Pair Correlation Function ◽  
Pair Correlation ◽  
Two Dimensional ◽  
Simulation Results

Quantitative Model for Clusters of String-like Cooperative Motion in a Coarse-Grained Glass-Forming Polymer Melt

2014 ◽  
Vol 1622 ◽  
pp. 95-111 ◽  
Author(s):  
Beatriz A Pazmiño Betancourt ◽  
Jack F. Douglas ◽  
Francis W. Starr
Keyword(s):  
Configurational Entropy ◽  
Polymer Melt ◽  
Quantitative Model ◽  
Coarse Grained ◽  
Residual Entropy ◽  
Arrhenius Behavior ◽  
String Length ◽  
Glass Forming ◽  
Free Parameters ◽  
Lower Temperature

ABSTRACTWe apply a living polymerization theory to describe cooperative string-like particle rearrangement clusters observed in simulations of a coarse-grained polymer melt. The theory quantitatively describes the interrelation between the average string length L, configurational entropy Sconf, and the order parameter for string assembly Φ without free parameters. Combining this theory with the Adam-Gibbs (AG) model allows us to predict the relaxation time τ in a lower temperature T range than accessible by current simulations. In particular, the combined theories suggest a return to Arrhenius behavior near Tg and a low T residual entropy, thus avoiding a Kauzmann ‘entropy crisis’.

Analysis of spin-echo small-angle neutron scattering measurements

2008 ◽  
Vol 41 (5) ◽  
pp. 868-885 ◽  
Author(s):  
Robert Andersson ◽  
Léon F. van Heijkamp ◽  
Ignatz M. de Schepper ◽  
Wim G. Bouwman
Keyword(s):  
Correlation Function ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Spin Echo ◽  
Pair Correlation ◽  
Real Space ◽  
Density Correlation ◽  
Measurement Models ◽  
Space Technique

Spin-echo small-angle neutron scattering (SESANS) is, in contrast to conventional small-angle neutron scattering (SANS), a real-space technique. SESANS measures the projection of the density–density correlation function of a sample, rather than, as in SANS, its Fourier transform. This paper introduces a toolkit for interpretion and analysis of a SESANS measurement. Models that are used in SANS are discussed and translated into a SESANS formalism. These models can be used to analyse and fit the data obtained by SESANS. Dilute, concentrated, random, fractal and anisotropic density distributions are considered. Numerical methods used to calculate the projection from numerical data are presented, either by using Fourier transformation orviathe real-space pair correlation function.

Quantifying chain reptation in entangled polymer melts: Topological and dynamical mapping of atomistic simulation results onto the tube model

2010 ◽  
Vol 132 (12) ◽  
pp. 124904 ◽  
Author(s):  
Pavlos S. Stephanou ◽  
Chunggi Baig ◽  
Georgia Tsolou ◽  
Vlasis G. Mavrantzas ◽  
Martin Kröger
Keyword(s):  
Atomistic Simulation ◽  
Polymer Melts ◽  
Tube Model ◽  
Entangled Polymer ◽  
Simulation Results ◽  
Entangled Polymer Melts ◽  
Dynamical Mapping

A highly coarse-grained model to simulate entangled polymer melts

2012 ◽  
Vol 136 (14) ◽  
pp. 144903 ◽  
Author(s):  
You-Liang Zhu ◽  
Hong Liu ◽  
Zhong-Yuan Lu
Keyword(s):  
Polymer Melts ◽  
Coarse Grained ◽  
Coarse Grained Model ◽  
Entangled Polymer ◽  
Entangled Polymer Melts
Sign in / Sign up

Export Citation Format

Share Document