Buckling of Graphene Embedded in Polymer Matrix Under Compression

Understanding the mechanical behaviors of graphene under different stress states is crucial to their applications. Comparing with the bucking behavior of free standing graphene under compression, the monolayer graphene embedded in the polymer matrix has a higher critical buckling load and smaller atomic length scale wavelengths as well as buckling amplitudes. In this paper, the molecular dynamics (MD) method is adopted to study the buckling behaviors of embedded graphene under uniaxial compression. Two MD models are built, namely the hybrid MD/continuum nanomechanics model and the full MD model. Periodical boundary conditions are applied in the MD simulations. Graphene sheets with different aspect ratios are considered and it is observed that the critical buckling strain of graphene sheets embedded in polymer matrix is independent of their aspect ratios. The current simulation results match well with the reported experimental results. Furthermore, it is demonstrated that the current simulation method can produce clear buckling shapes, which are difficult to observe in nanoscale experiments.

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Stress Corrosion Cracking of Graphene

Volume 12: Mechanics of Solids, Structures, and Fluids ◽

10.1115/imece2020-23842 ◽

2020 ◽

Author(s):

Mohan S. R. Elapolu ◽

Alireza Tabarraei

Keyword(s):

Stress Corrosion ◽

Graphene Sheet ◽

Stress Corrosion Cracking ◽

Crack Tip ◽

Md Simulations ◽

Corrosion Cracking ◽

Monolayer Graphene ◽

Graphene Sheets ◽

Carbon Radicals ◽

Edge Cracks

Abstract We use molecular dynamics (MD) simulations to study the stress corrosion cracking (SCC) of monolayer graphene sheets with an initial edge cracks. Two types of edge cracks are considered in the simulations; one with armchair edges and another one with zigzag edges. All the simulations are conducted at 300 K and the corrosive environment is O2 molecules. Tensile stresses are induced in the graphene sheet by applying mode–I loading. To understand the mechanism of the sub–critical crack growth during SCC, we expose the graphene sheets to O2 molecules at strains of 0.047 and 0.076. Our MD simulations capture the chemisorption process between the O2 molecules and pre–stressed graphene sheet. Oxygen molecules react with carbon radicals at the edges of the crack tip and gets adsorbed to the graphene surface. The atomic stresses in the vicinity of crack tip relaxes due to the adsorption of O2 molecule. Our results show that the reaction of O2 molecules with the carbon radicals at the crack tip can cause the failure of C–C bonds which leads to the sub critical cracking.

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Ubiquitous organic molecule-based free-standing nanowires with ultra-high aspect ratios

Nature Communications ◽

10.1038/s41467-021-24335-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Koshi Kamiya ◽

Kazuto Kayama ◽

Masaki Nobuoka ◽

Shugo Sakaguchi ◽

Tsuneaki Sakurai ◽

...

Keyword(s):

Critical Dimension ◽

High Energy ◽

Free Standing ◽

Dry Process ◽

3D Space ◽

Aspect Ratios ◽

Structural Functions ◽

Planar Structures ◽

Organic Nanostructures ◽

Straight Trajectory

AbstractThe critical dimension of semiconductor devices is approaching the single-nm regime, and a variety of practical devices of this scale are targeted for production. Planar structures of nano-devices are still the center of fabrication techniques, which limit further integration of devices into a chip. Extension into 3D space is a promising strategy for future; however, the surface interaction in 3D nanospace make it hard to integrate nanostructures with ultrahigh aspect ratios. Here we report a unique technique using high-energy charged particles to produce free-standing 1D organic nanostructures with high aspect ratios over 100 and controlled number density. Along the straight trajectory of particles penetrating the films of various sublimable organic molecules, 1D nanowires were formed with approximately 10~15 nm thickness and controlled length. An all-dry process was developed to isolate the nanowires, and planar or coaxial heterojunction structures were built into the nanowires. Electrical and structural functions of the developed standing nanowire arrays were investigated, demonstrating the potential of the present ultrathin organic nanowire systems.

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Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.226-228.1755 ◽

2012 ◽

Vol 226-228 ◽

pp. 1755-1759

Author(s):

Hua Zhang ◽

Fei Li ◽

Yu Wei Gao

Keyword(s):

Elastic Modulus ◽

Asphalt Concrete ◽

Poisson Ratio ◽

Dynamic Properties ◽

Dynamic Performance ◽

Dynamic Strength ◽

Confining Pressure ◽

Mechanical Behaviors ◽

One Dimensional ◽

Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

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Insights into Relative Lower Frequencies and Buckling Loads of Monolayer Graphene Sheets via Nonlocal Elasticity Theory: Size-Dependent Young's Modulus Approach

Nanoscience and Nanotechnology Letters ◽

10.1166/nnl.2013.1665 ◽

2013 ◽

Vol 5 (10) ◽

pp. 1097-1102

Author(s):

T. Murmu ◽

S. Adhikari ◽

M. A. McCarthy ◽

C. Y. Wang

Keyword(s):

Elasticity Theory ◽

Young’S Modulus ◽

Nonlocal Elasticity ◽

Young's Modulus ◽

Nonlocal Elasticity Theory ◽

Monolayer Graphene ◽

Graphene Sheets ◽

Buckling Loads ◽

Size Dependent ◽

Lower Frequencies

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van der Waals effect on the nanoindentation response of free standing monolayer graphene

Carbon ◽

10.1016/j.carbon.2013.01.083 ◽

2013 ◽

Vol 57 ◽

pp. 357-362 ◽

Cited By ~ 21

Author(s):

Lixin Zhou ◽

Yugang Wang ◽

Guoxin Cao

Keyword(s):

Van Der Waals ◽

Monolayer Graphene ◽

Free Standing ◽

Van Der Waals Effect

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Molecular Dynamics Simulation of a Pullout Test on a Carbon Nanotube in a Polymer Matrix

MRS Proceedings ◽

10.1557/opl.2014.715 ◽

2014 ◽

Vol 1700 ◽

pp. 61-66

Author(s):

Guttormur Arnar Ingvason ◽

Virginie Rollin

Keyword(s):

Molecular Dynamics ◽

Polymer Matrix ◽

Large Scale ◽

Md Simulations ◽

Dynamics Simulation ◽

Atomistic Simulations ◽

Polymer Molecules ◽

Molecular Potential ◽

Pull Out ◽

Walled Carbon Nanotubes

ABSTRACTAdding single walled carbon nanotubes (SWCNT) to a polymer matrix can improve the delamination properties of the composite. Due to the complexity of polymer molecules and the curing process, few 3-D Molecular Dynamics (MD) simulations of a polymer-SWCNT composite have been run. Our model runs on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), with a COMPASS (Condensed phase Optimized Molecular Potential for Atomistic Simulations Studies) potential. This potential includes non-bonded interactions, as well as bonds, angles and dihedrals to create a MD model for a SWCNT and EPON 862/DETDA (Diethyltoluenediamine) polymer matrix. Two simulations were performed in order to test the implementation of the COMPASS parameters. The first one was a tensile test on a SWCNT, leading to a Young’s modulus of 1.4 TPa at 300K. The second one was a pull-out test of a SWCNT from an originally uncured EPON 862/DETDA matrix.

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Interface and Interphase in Polymer Nanocomposites with Bare and Core-Shell Gold Nanoparticles

Polymers ◽

10.3390/polym13040541 ◽

2021 ◽

Vol 13 (4) ◽

pp. 541 ◽

Cited By ~ 1

Author(s):

Albert J. Power ◽

Ioannis N. Remediakis ◽

Vagelis Harmandaris

Keyword(s):

Polymer Nanocomposites ◽

Polymer Matrix ◽

Md Simulations ◽

Polymer Chains ◽

Core Shell ◽

Wulff Construction ◽

Density Profiles ◽

Au Nps ◽

Polymeric Chains ◽

Terminal Dynamics

Metal nanoparticles are used to modify/enhance the properties of a polymer matrix for a broad range of applications in bio-nanotechnology. Here, we study the properties of polymer/gold nanoparticle (NP) nanocomposites through atomistic molecular dynamics, MD, simulations. We probe the structural, conformational and dynamical properties of polymer chains at the vicinity of a gold (Au) NP and a functionalized (core/shell) Au NP, and compare them against the behavior of bulk polyethylene (PE). The bare Au NPs were constructed via a systematic methodology starting from ab-initio calculations and an atomistic Wulff construction algorithm resulting in the crystal shape with the minimum surface energy. For the functionalized NPs the interactions between gold atoms and chemically adsorbed functional groups change their shape. As a model polymer matrix we consider polyethylene of different molecular lengths, from the oligomer to unentangled Rouse like systems. The PE/Au interaction is parametrized via DFT calculations. By computing the different properties the concept of the interface, and the interphase as well, in polymer nanocomposites with metal NPs are critically examined. Results concerning polymer density profiles, bond order parameter, segmental and terminal dynamics show clearly that the size of the interface/interphase, depends on the actual property under study. In addition, the anchored polymeric chains change the behavior/properties, and especially the chain density profile and the dynamics, of the polymer chain at the vicinity of the Au NP.

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