scholarly journals Ionic Polymer Nanocomposites Subjected to Uniaxial Extension: A Nonequilibrium Molecular Dynamics Study

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4001
Author(s):  
Ahmad Moghimikheirabadi ◽  
Argyrios V. Karatrantos ◽  
Martin Kröger
Keyword(s):  
Molecular Dynamics ◽  
Strain Rate ◽  
Polymer Nanocomposites ◽  
Volume Fraction ◽  
Uniaxial Extension ◽  
Coarse Grained ◽  
Nonequilibrium Molecular Dynamics ◽  
Simultaneous Increase ◽  
Nanoparticle Volume Fraction ◽  
Ionic Polymer

We explore the behavior of coarse-grained ionic polymer nanocomposites (IPNCs) under uniaxial extension up to 800% strain by means of nonequilibrium molecular dynamics simulations. We observe a simultaneous increase of stiffness and toughness of the IPNCs upon increasing the engineering strain rate, in agreement with experimental observations. We reveal that the excellent toughness of the IPNCs originates from the electrostatic interaction between polymers and nanoparticles, and that it is not due to the mobility of the nanoparticles or the presence of polymer–polymer entanglements. During the extension, and depending on the nanoparticle volume fraction, polymer–nanoparticle ionic crosslinks are suppressed with the increase of strain rate and electrostatic strength, while the mean pore radius increases with strain rate and is altered by the nanoparticle volume fraction and electrostatic strength. At relatively low strain rates, IPNCs containing an entangled matrix exhibit self-strengthening behavior. We provide microscopic insight into the structural, conformational properties and crosslinks of IPNCs, also referred to as polymer nanocomposite electrolytes, accompanying their unusual mechanical behavior.

A MULTI-SCALE NONEQUILIBRIUM MOLECULAR DYNAMICS ALGORITHM AND ITS APPLICATIONS

2009 ◽  
Vol 01 (03) ◽  
pp. 405-420 ◽  
Author(s):  
NI SHENG ◽  
SHAOFAN LI
Keyword(s):  
Molecular Dynamics ◽  
Local Equilibrium ◽  
Random Force ◽  
Coarse Grained ◽  
Nonequilibrium Molecular Dynamics ◽  
Fine Scale ◽  
Coarse Scale ◽  
Fe Method ◽  
Time Step ◽  
Multi Scale

In this paper, we introduce a multi-scale nonequilibrium molecular dynamics (MS-NEMD) model that is capable of simulating nano-scale thermal–mechanical interactions. Recent simulation results using the MS-NEMD model are presented. The MS-NEMD simulation generalises the nonequilibrium molecular dynamics (NEMD) simulation to the setting of concurrent multi-scale simulation. This multi-scale framework is based on a novel concept of multi-scale canonical ensemble. Under this concept, each coarse scale finite element (FE) node acts as a thermostat, while the atoms associated with each node are assumed to be in a local equilibrium state within one coarse scale time step. The coarse scale mean field is solved by the FE method based on a coarse-grained thermodynamics model; whereas in the fine scale the NEMD simulation is driven by the random force that is regulated by the inhomogeneous continuum filed through a distributed Nośe–Hoover thermostat network. It is shown that the fine scale distribution function is canonical in the sense that it obeys a drifted local Boltzmann distribution.

scholarly journals Cyclic deformation behaviour and stability of grain-refined 301LN austenitic stainless structure

2018 ◽  
Vol 165 ◽  
pp. 06005 ◽  
Author(s):  
Jiří Man ◽  
Antti Järvenpää ◽  
Matias Jaskari ◽  
Ivo Kuběna ◽  
Stanislava Fintová ◽  
...  
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Early Stage ◽  
Low Cycle Fatigue ◽  
Deformation Behaviour ◽  
Polarized Light ◽  
Constant Strain Rate ◽  
Coarse Grained ◽  
Grain Sizes ◽  
Cyclic Straining

Low cycle fatigue (LCF) behaviour of metastable austenitic 301LN stainless steel with different grain sizes – coarse-grained (13 μm), fine-grained (1.4 μm) and ultrafine-grained (0.6 μm) – produced by reversion annealing after prior cold rolling was investigated. Fully symmetrical LCF tests with constant total strain amplitudes of 0.5% and 0.6% were performed at room temperature with a low constant strain rate of 2×10-3 s-1. Microstructural changes in different positions within the gauge part of the specimens were examined by optical microscopy (polarized light) and electron backscatter diffraction (EBSD) technique; for quantitative assessment of the volume fraction of deformation induced martensite (DIM) a Feritscope FMP 30 was adopted. The cyclic stress-strain response and specific changes of hysteresis loop shapes in the very early stage of cycling are confronted with the character of DIM formation and its distribution in the whole volume of the material. A possible effect of strain rate (frequency of cycling) on the destabilization of austenitic structure during cyclic straining of materials with different grain sizes is highlighted.

High-Strain-Rate Plastic Flow Studied via Nonequilibrium Molecular Dynamics

1982 ◽  
Vol 48 (26) ◽  
pp. 1818-1820 ◽  
Author(s):  
William G. Hoover ◽  
Anthony J. C. Ladd ◽  
Bill Moran
Keyword(s):  
Molecular Dynamics ◽  
High Strain Rate ◽  
Strain Rate ◽  
Plastic Flow ◽  
High Strain ◽  
Nonequilibrium Molecular Dynamics

scholarly journals Homogenization of Mutually Immiscible Polymers Using Nanoscale Effects: A Theoretical Study

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Sarah Montes ◽  
Agustín Etxeberria ◽  
Javier Rodriguez ◽  
Jose A. Pomposo
Keyword(s):  
Molecular Weight ◽  
Polymer Nanocomposites ◽  
Room Temperature ◽  
Theoretical Study ◽  
Volume Fraction ◽  
Mean Field Theory ◽  
Mean Field ◽  
Nanoparticle Volume Fraction ◽  
Immiscible Polymers ◽  
Complete Miscibility

A theoretical study to investigate homogenization of mutually immiscible polymers using nanoscale effects has been performed. Specifically, the miscibility behavior of all-polymer nanocomposites composed of linear-polystyrene (PS) chains and individual cross-linked poly(methyl methacrylate)-nanoparticles (PMMA-NPs) has been predicted. By using a mean field theory accounting for combinatorial interaction energy and nanoparticle-driven effects, phase diagrams were constructed as a function of PMMA-NP size, PS molecular weight, and temperature. Interestingly, complete miscibility (i.e., homogeneity) was predicted from room temperature to 675 K for PMMA-nanoparticles with radius less than ~7 nm blended with PS chains (molecular weight 150 kDa, nanoparticle volume fraction 20%) in spite of the well-known immiscibility between PS and PMMA. Several nanoscale effects affecting miscibility in PMMA-NP/PS nanocomposites involving small PMMA-nanoparticles are discussed.

Rheological and Structural Properties of Associated Polymer Networks Studied via Nonequilibrium Molecular Dynamics Simulation

2021 ◽  
Author(s):  
Yuankun Peng ◽  
Tongkui Yue ◽  
Sai Li ◽  
Ke Gao ◽  
Yachen Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Structural Properties ◽  
Functional Groups ◽  
Molecular Level ◽  
Polymer Networks ◽  
Dynamics Simulation ◽  
Coarse Grained ◽  
Nonequilibrium Molecular Dynamics ◽  
Nonequilibrium Molecular Dynamics Simulation

An intensive understanding of the rheological and structural properties of polymer physical networks formed via the associative functional groups at the molecular level is still lacking. Herein, we employed coarse-grained...

Simultaneous uniaxial extensional deformation and cylindrical confinement of block copolymers using non-equilibrium molecular dynamics

Soft Matter ◽  
2018 ◽  
Vol 14 (8) ◽  
pp. 1389-1396 ◽  
Author(s):  
George L. Shebert ◽  
Yong Lak Joo
Keyword(s):  
Molecular Dynamics ◽  
Block Copolymers ◽  
Coarse Grained ◽  
Nonequilibrium Molecular Dynamics ◽  
Combined Effects ◽  
Extensional Deformation ◽  
Non Equilibrium Molecular Dynamics ◽  
Symmetric Block ◽  
Non Equilibrium

Using coarse-grained nonequilibrium molecular dynamics, symmetric block copolymers are simulated under the combined effects of cylindrical confinement and uniaxial extensional deformation.

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