scholarly journals Investigation of Crystallization and Relaxation Effects in Coarse-Grained Polyethylene Systems after Uniaxial Stretching

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4466
Author(s):  
Dirk Grommes ◽  
Martin Schenk ◽  
Olaf Bruch ◽  
Dirk Reith
Keyword(s):  
Real Life ◽  
Crystallization Rate ◽  
Polymer Processing ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Mechanical Relaxation ◽  
Uniaxial Stretching ◽  
Relaxation Effects ◽  
Shrinkage And Swelling ◽  
Dynamics Simulations

In this study, we investigate the thermo-mechanical relaxation and crystallization behavior of polyethylene using mesoscale molecular dynamics simulations. Our models specifically mimic constraints that occur in real-life polymer processing: After strong uniaxial stretching of the melt, we quench and release the polymer chains at different loading conditions. These conditions allow for free or hindered shrinkage, respectively. We present the shrinkage and swelling behavior as well as the crystallization kinetics over up to 600 ns simulation time. We are able to precisely evaluate how the interplay of chain length, temperature, local entanglements and orientation of chain segments influences crystallization and relaxation behavior. From our models, we determine the temperature dependent crystallization rate of polyethylene, including crystallization onset temperature.

A Finite Element-Based Coarse-Grained Model for Cell–Nanomaterial Interactions by Combining Absolute Nodal Coordinate Formula and Brownian Dynamics

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Teng Ma ◽  
Yuanpeng Liu ◽  
Guochang Lin ◽  
Changguo Wang ◽  
Huifeng Tan
Keyword(s):  
Finite Element ◽  
Brownian Dynamics ◽  
Lipid Membrane ◽  
Contact Region ◽  
Detection Algorithm ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Absolute Nodal Coordinate ◽  
Coarse Grained Model ◽  
Dynamics Simulations

Abstract A fundamental understanding of the interactions between one-dimensional nanomaterials and the cell membrane is of great importance for assessing the hazardous effects of viruses and improving the performance of drug delivery. Here, we propose a finite element-based coarse-grained model to describe the cell entry of nanomaterials based on an absolute nodal coordinate formula and Brownian dynamics. The interactions between nanoparticles and lipid membrane are described by the Lennard–Jones potential, and a contact detection algorithm is used to determine the contact region. Compared with the theoretical and published experimental results, the correctness of the model has been verified. We take two examples to test the robustness of the model: the endocytosis of nanorods grafted with polymer chains and simultaneous entry of multiple nanorods into a lipid membrane. It shows that the model can not only capture the effect of ligand–receptor binding on the penetration but also accurately characterize the cooperative or separate entry of multiple nanorods. This coarse-grained model is computationally highly efficient and will be powerful in combination with molecular dynamics simulations to provide an understanding of cell–nanomaterial interactions.

Scattering patterns and stress–strain relations on phase-separated ABA block copolymers under uniaxial elongating simulations

Soft Matter ◽  
2019 ◽  
Vol 15 (5) ◽  
pp. 926-936 ◽  
Author(s):  
Katsumi Hagita ◽  
Keizo Akutagawa ◽  
Tetsuo Tominaga ◽  
Hiroshi Jinnai
Keyword(s):  
Molecular Dynamics ◽  
Block Copolymers ◽  
Molecular Dynamics Simulations ◽  
Coarse Grained ◽  
Two Dimensional ◽  
Stress Strain ◽  
Uniaxial Stretching ◽  
Dynamics Simulations ◽  
Coarse Grained Molecular Dynamics

To develop molecularly based interpretations of the two-dimensional scattering patterns (2DSPs) of phase-separated block copolymers (BCPs), we performed coarse-grained molecular dynamics simulations of ABA tri-BCPs under uniaxial stretching for block-fractions where the A-segment (glassy domain) is smaller than the B-segment (rubbery domain), and estimated the behaviour of their 2DSPs.

Molecular dynamics simulation of thermo-mechanical behaviour of elastomer cross-linked via multifunctional zwitterions

2019 ◽  
Vol 21 (38) ◽  
pp. 21615-21625 ◽  
Author(s):  
Naveed Athir ◽  
Ling Shi ◽  
Sayyed Asim Ali Shah ◽  
Zhiyu Zhang ◽  
Jue Cheng ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Molecular Dynamics Simulations ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Coarse Grained ◽  
Dynamics Simulations

Coarse-grained (CG) molecular dynamics simulations have been employed to study the thermo-mechanical response of a physically cross-linked network composed of zwitterionic moieties and fully flexible elastomeric polymer chains.

Effects of Copolymer Sequence on Adsorption and Dynamics Near Nanoparticle Surfaces in Simulated Polymer Nanocomposites

2020 ◽  
Vol 48 (1) ◽  
pp. 62-75 ◽  
Author(s):  
Alex J. Trazkovich ◽  
Tarik H. Akyuz ◽  
Lisa M. Hall
Keyword(s):  
Random Sequence ◽  
Polymer Nanocomposite ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Linear Polymers ◽  
Covalent Bonds ◽  
Sequence Effects ◽  
Filler Particles ◽  
Dynamics Simulations ◽  
Styrene Butadiene

ABSTRACT We study a simple nanocomposite, consisting of a single spherical nanoparticle in a dense melt of coarse-grained copolymer chains, using molecular dynamics simulations. The polymers contain equal amounts of two monomer types, which differ only in their monomer-nanoparticle interaction (adsorption) strengths, and are placed in a random sequence or in a sequence of alternating blocks with various block lengths. This model is motivated by a need to understand copolymer sequence effects relevant to designing tire tread compounds, given the synthetic ability to adjust copolymer architecture (e.g., amount of blockiness) in styrene-butadiene rubbers and the ability to choose fillers and covering agents that functionalize the filler particles to give them different affinities for the styrene and butadiene monomers (it is also possible to use coupling agents, which form covalent bonds between filler particles and polymer chains). Our simple, generalized model considers linear polymers of uniform length that are not cross-linked, and thus we do not attempt to capture the overall mechanical properties of tire tread materials. Instead, we focus our analysis on how copolymer sequence impacts polymer adsorption on the nanoparticle, known to be a significant factor in determining polymer nanocomposite properties. We find that copolymer sequence impacts both the range and magnitude of the interphase of slowed dynamics surrounding the nanoparticle, with longer block lengths yielding a greater reduction in mobility over a wider region.

Polymer-grafted nanoparticles prepared via a grafting-from strategy: a computer simulation study

2018 ◽  
Vol 20 (27) ◽  
pp. 18400-18409 ◽  
Author(s):  
Long Li ◽  
Cheng Han ◽  
Dan Xu ◽  
Ji-Yuan Xing ◽  
Yao-Hong Xue ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Reaction Model ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Computer Simulation Study ◽  
Grafted Nanoparticles ◽  
Dynamics Simulations ◽  
Grafting From ◽  
Stochastic Reaction

Nanoparticles (NPs) grafted with polymer chains prepared via a grafting-from strategy are studied through coarse-grained molecular dynamics simulations combined with our stochastic reaction model.

Mechanisms of Mechanical Behavior of Filled Rubber by Coarse-Grained Molecular Dynamics Simulations

2020 ◽  
Vol 48 (2) ◽  
pp. 78-106 ◽  
Author(s):  
Takashi Kojima ◽  
Masataka Koishi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Conformational Changes ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Reinforcement Effect ◽  
Stress Softening ◽  
Filled Rubber ◽  
Dynamics Simulations ◽  
Polymer Density

ABSTRACT: We reproduced mechanical behaviors, such as the reinforcement effect, hysteresis, and stress softening, of filled rubber under cyclic deformations using coarse-grained molecular dynamics simulations. We measured polymer density distribution in the nonload equilibrium state and conformational changes in polymer chains during deformation for dispersed and aggregated filler structures. We found that the polymer–filler attractive interactions increase the polymer density in the vicinity of fillers and decrease the polymer density in the other regions. The polymer bonds that connect polymer particles away from fillers are extended when the polymer density decreases. This alteration increases the modulus of the polymer phase, and the reinforcement effect appears. For aggregated filler structures, the polymer chains interacting with adjacent fillers act as a bridge between these fillers and increase the modulus, especially when the strain is low. To test the mechanisms of hysteresis and stress softening, we measured the changes in the polymer paths. A polymer path is the minimal path of polymer networks between two fillers; in other words, it is the “bridge” that connects two fillers. We found that the polymer paths increase in length, especially during primary loading, because of polymer adsorption/desorption on the filler surface to adjust the change of filler positions. It was also found that the influence of the filler structure diminishes in the first loading. During subsequent unloading, a long path does not become a short path again but will be folded even though the filler distance reduces. Hence, the change in the polymer paths in the second cycle is smaller than that in the first cycle because the polymer path is just unfolded. We confirmed the hysteresis and stress-softening result from these conformational changes. In this article, we also discuss the recovery mechanism for stress softening and the history dependence.

Coarse-Grained Molecular Modeling of Composite Interfaces

2005 ◽  
Vol 502 ◽  
pp. 39-44
Author(s):  
Vincent B.C. Tan ◽  
M. Deng ◽  
Tong Earn Tay
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Ab Initio Molecular Dynamics ◽  
Attractive Potential ◽  
Dynamics Simulations ◽  
Computational Resources ◽  
Nonlinear Elastic

The interface of fiber and matrix strongly influences the performance and strength of fiber-reinforced composite materials. Due to the limitations of continuum mechanics at the nanometer length scale, atomistic level computer simulation has started to play an important role in the understanding of such interfacial systems. Our study focuses on a typical crosslinked interfacial system of glass-epoxy composite with the presence of silanes. To explore the mechanical properties of the interfacial network system, Coarse-grained Molecular Dynamics is used. Currently it is not possible to study mechanical properties of interfacial systems purely through ab initio molecular dynamics simulations because of the huge computational resources required. Although pure atomistic classical molecular dynamics simulations have been used to study systems comprising billions of atoms, classical MD simulation do not take into account the effects of crosslinking of molecular chains. A new force field, which combines the Lennard-Jones potential and a finiteextensible nonlinear elastic attractive potential, is proposed and incorporated in a bead-spring model to simulate glass/epoxy interfacial system with the crosslinked structure of silanes. The finite-extensible nonlinear elastic attractive potential is included to control the motion and breakage of polymer chains. Interfacial adhesion and mechanical properties were studied through the simulation of mechanically separating the interfacial system.

Parameterization of Divalent Cations for Coarse-Grained Simulations

2020 ◽  
Author(s):  
Florencia Klein ◽  
Daniela Cáceres-Rojas ◽  
Monica Carrasco ◽  
Juan Carlos Tapia ◽  
Julio Caballero ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Metal Ions ◽  
Molecular Dynamics Simulations ◽  
Divalent Cations ◽  
Computational Cost ◽  
Data Bank ◽  
Coarse Grained ◽  
Interaction Parameters ◽  
Dynamics Simulations ◽  
Dynamical Description

<p>Although molecular dynamics simulations allow for the study of interactions among virtually all biomolecular entities, metal ions still pose significant challenges to achieve an accurate structural and dynamical description of many biological assemblies. This is particularly the case for coarse-grained (CG) models. Although the reduced computational cost of CG methods often makes them the technique of choice for the study of large biomolecular systems, the parameterization of metal ions is still very crude or simply not available for the vast majority of CG- force fields. Here, we show that incorporating statistical data retrieved from the Protein Data Bank (PDB) to set specific Lennard-Jones interactions can produce structurally accurate CG molecular dynamics simulations. Using this simple approach, we provide a set of interaction parameters for Calcium, Magnesium, and Zinc ions, which cover more than 80% of the metal-bound structures reported on the PDB. Simulations performed using the SIRAH force field on several proteins and DNA systems show that using the present approach it is possible to obtain non-bonded interaction parameters that obviate the use of topological constraints. </p>

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