Molecular dynamics simulations of mechanical properties of epoxy-amine: cross-linker type and conversion degree effects

2021 ◽  
Author(s):  
Yongqin Zhang ◽  
Hua Yang ◽  
Yaguang Sun ◽  
Xiangrui Zheng ◽  
Yafang Guo
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Active Sites ◽  
Phenol Formaldehyde ◽  
Md Simulations ◽  
Crosslinking Density ◽  
Molecular Structures ◽  
Conversion Degree ◽  
Epoxy Amine ◽  
Cross Linker

Abstract In this work, molecular dynamics (MD) simulations are conducted to study the thermo-mechanical properties of a family of thermosetting epoxy-amine. The crosslinked epoxy resin EPON862 with a series of cross-linkers are built and simulated under the polymer consistent force-field (PCFF). Three types of curing-agents (rigidity1,3-phenylenediamine (1,3-P), 4,4-diaminodiphenylmethane (DDM), and phenol-formaldehyde-ethylenediamine (PFE)) with different number of active sites are selected in the simulations. We focus on the effects of the cross-linkers on thermo-mechanical properties such as density, glass transition temperature (T g), elastic constants, and strength. Our simulations show a significant increase in T g, Young’s modulus and yield stress with the increase of conversion degree. The simulation results revealed that the mechanical properties of thermosetting polymers are strongly dependent on the molecular structures of cross-linker and network topological properties, such as end-to-end distance, crosslinking density and conversion degree.

scholarly journals Exploring the Cold-Adaptation Mechanism of Serine Hydroxymethyltransferase by Comparative Molecular Dynamics Simulations

2021 ◽  
Vol 22 (4) ◽  
pp. 1781
Author(s):  
Zhi-Bi Zhang ◽  
Yuan-Ling Xia ◽  
Guang-Heng Dong ◽  
Yun-Xin Fu ◽  
Shu-Qun Liu
Keyword(s):  
Molecular Dynamics ◽  
Cold Adaptation ◽  
Active Sites ◽  
Structural Parameters ◽  
Md Simulations ◽  
Molecular Structures ◽  
Serine Hydroxymethyltransferase ◽  
Adaptation Mechanism ◽  
Thermo Stability ◽  
Dynamics Simulations

Cold-adapted enzymes feature a lower thermostability and higher catalytic activity compared to their warm-active homologues, which are considered as a consequence of increased flexibility of their molecular structures. The complexity of the (thermo)stability-flexibility-activity relationship makes it difficult to define the strategies and formulate a general theory for enzyme cold adaptation. Here, the psychrophilic serine hydroxymethyltransferase (pSHMT) from Psychromonas ingrahamii and its mesophilic counterpart, mSHMT from Escherichia coli, were subjected to μs-scale multiple-replica molecular dynamics (MD) simulations to explore the cold-adaptation mechanism of the dimeric SHMT. The comparative analyses of MD trajectories reveal that pSHMT exhibits larger structural fluctuations and inter-monomer positional movements, a higher global flexibility, and considerably enhanced local flexibility involving the surface loops and active sites. The largest-amplitude motion mode of pSHMT describes the trends of inter-monomer dissociation and enlargement of the active-site cavity, whereas that of mSHMT characterizes the opposite trends. Based on the comparison of the calculated structural parameters and constructed free energy landscapes (FELs) between the two enzymes, we discuss in-depth the physicochemical principles underlying the stability-flexibility-activity relationships and conclude that (i) pSHMT adopts the global-flexibility mechanism to adapt to the cold environment and, (ii) optimizing the protein-solvent interactions and loosening the inter-monomer association are the main strategies for pSHMT to enhance its flexibility.

EFFECTS OF STOICHIOMETRY ON PROPERTIES OF DGEBF/DETDA EPOXY USING MOLECULAR DYNAMICS

2021 ◽  
Author(s):  
SAGAR PATIL ◽  
MICHAEL OLAYA ◽  
PRATHAMESH DESHPANDE ◽  
MARIANNA MAIARÙ ◽  
GREGORY ODEGARD
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Modeling ◽  
Bulk Modulus ◽  
Mass Density ◽  
Strong Dependence ◽  
Crosslinking Density ◽  
Mechanical Deformation ◽  
Epoxy System ◽  
Reactive Interface

This article details the molecular modeling of full and off-stoichiometry models of the DGEBF/DETDA epoxy system using Molecular Dynamics to predict the mechanical properties as a function of the crosslinking density. The Reactive Interface Force Field (IFF-R) is implemented in this work to simulate mechanical deformation. The “fix bond/react” command in LAMMPS is used to simulate crosslinking between epoxy monomers. The results show that the predicted mass density, volumetric shrinkage, and bulk modulus have a strong dependence on the stoichiometry of the epoxy.

scholarly journals Polydopamine and eumelanin molecular structures investigated with ab initio calculations

2017 ◽  
Vol 8 (2) ◽  
pp. 1631-1641 ◽  
Author(s):  
Chun-Teh Chen ◽  
Francisco J. Martin-Martinez ◽  
Gang Seob Jung ◽  
Markus J. Buehler
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Md Simulations ◽  
Molecular Structures ◽  
Brute Force ◽  
Functional Theory

A set of computational methods that contains a brute-force algorithmic generation of chemical isomers, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations is reported and applied to investigate nearly 3000 probable molecular structures of polydopamine (PDA) and eumelanin.

Mechanical Properties of α-Helices Estimated Using Molecular Dynamics and Finite Element Simulations

2008 ◽  
Author(s):  
Peyman Honarmandi ◽  
Philip Bransford ◽  
Roger D. Kamm
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Finite Element ◽  
Solid Mechanics ◽  
Normal Mode Analysis ◽  
Computational Cost ◽  
Md Simulations ◽  
Elastic Stiffness ◽  
Mode Analysis ◽  
Molecular Volume

Mechanical properties of biomolecules and their response to mechanical forces may be studied using Molecular Dynamics (MD) simulations. However, high computational cost is a primary drawback of MD simulations. This paper presents a computational framework based on the integration of the Finite Element Method (FEM) with MD simulations to calculate the mechanical properties of polyalanine α-helix proteins. In this method, proteins are treated as continuum elastic solids with molecular volume defined exclusively by their atomic surface. Therefore, all solid mechanics theories would be applicable for the presumed elastic media. All-atom normal mode analysis is used to calculate protein’s elastic stiffness as input to the FEM. In addition, constant force molecular dynamics (CFMD) simulations can be used to predict other effective mechanical properties, such as the Poisson’s Ratio. Force versus strain data help elucidate the mechanical behavior of α-helices upon application of constant load. The proposed method may be useful in identifying the mechanical properties of any protein or protein assembly with known atomic structure.

Unusually high flexibility of graphene–Cu nanolayered composites under bending

2019 ◽  
Vol 21 (31) ◽  
pp. 17393-17399 ◽  
Author(s):  
Yuxin Zhao ◽  
Xiaoyi Liu ◽  
Jun Zhu ◽  
Sheng-Nian Luo
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Analytical Model ◽  
Md Simulations ◽  
High Flexibility

The mechanical properties of graphene–Cu nanolayered (GCuNL) composites under bend loading are investigated via an energy-based analytical model and molecular dynamics (MD) simulations.

Diffusion of Epoxy Molecules on the Chemically Modified Graphene: A Molecular Dynamics Simulation Study

2015 ◽  
Vol 817 ◽  
pp. 803-808 ◽  
Author(s):  
Jian Wei Zhang ◽  
Cai Jiang ◽  
Gang Shi ◽  
Da Zhi Jiang
Keyword(s):  
Molecular Dynamics ◽  
Polymer Composites ◽  
Functional Groups ◽  
Md Simulations ◽  
Molecular Structures ◽  
Dynamics Simulation ◽  
Graphene Layers ◽  
Wall Structures ◽  
Modified Graphene ◽  
Main Factor

Buckypaper based polymer composites provides a new technical approach toward realizing conductive/structural multifunctional composites. Resin infiltration in the buckypaper is critical for the fabrication of buckypaper/polymer composites. To investigate the micro-infusion process of the polymer inside the paper, molecular dynamics (MD) simulations are conducted to study the diffusion behavior of epoxy molecules on the modified graphene and between graphene layers. The graphene molecular structures are constructed to represent the wall structures of the carbon nanotubes. Diffusion coefficients of the epoxy molecules on the graphene modified with different functionalization densities and interlayer distances are calculated. The results indicate that the functional groups increase the interfacial interactions between the epoxy molecules and graphene, however, largely decrease the diffusion speeds of the epoxy molecule. The simulations on the graphene layer systems indicate that, the viscous resistance of the resin is the main factor for retarding the diffusion of the epoxy molecules for the unmodified graphene layers; while for the modified graphene layers, functional groups are the main factor for retarding the resin diffusion

The Effects of Thermal Loading on the Mechanical Properties of Interfaces of Dissimilar Materials by Nanoindentation Simulations

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Ningbo Liao ◽  
Ping Yang ◽  
Miao Zhang ◽  
Wei Xue
Keyword(s):  
Heat Transfer ◽  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Thermal Cycling ◽  
Thermal Loading ◽  
Mechanical Test ◽  
Dissimilar Materials ◽  
Md Simulations ◽  
Test Models ◽  
Critical Consideration

Heat transfer across the interfaces of dissimilar materials is a critical consideration in a wide variety of scientific and engineering applications. In this paper, molecular dynamics (MD) simulations are conducted to investigate the effects of thermal loading on mechanical properties of Al–Cu and Cr–Cu interfaces. The mechanical properties are investigated by MD simulations of nanoindentation. Both the results of MD simulations and experiments show the Young’s modulus decrease after thermal cycling, and the Cr–Cu interface is more sensitive to the thermal loading than the Al–Cu interface. The thermal loading and mechanical test models proposed here can be used to evaluate interfacial properties under the effects of heat transferring.

Temperature Effect on Tensile Behavior of Helical Multi-Shell Gold Nanowires

2006 ◽  
Vol 505-507 ◽  
pp. 385-390 ◽  
Author(s):  
Jenn Sen Lin ◽  
Shin Pon Ju ◽  
Yu-Lin Peng ◽  
Wen Jay Lee
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Testing ◽  
Constant Strain Rate ◽  
Helical Structure ◽  
Md Simulations ◽  
Tensile Behavior ◽  
Gold Nanowires ◽  
Deformation Behaviors ◽  
Fcc Structure

This study performs molecular dynamics (MD) simulations to investigate the tensile behavior of Helical Multi-Shell (HMS) gold nanowires. As their name suggests, these nanowires have a multi-shell helical structure rather than a conventional bulk FCC structure. The mechanical properties and deformation behaviors of the 7-1, 11-4 and 14-7-1 HMS structures are examined under tensile testing at temperatures between 4K and 300 K and a constant strain rate of 0.003% −1 ps . The results reveal that temperature influences the yielding stress, the Young’s modulus, and the deformation behaviors of HMS nanowires. The yielding stress of the 7-1 structure is found to be higher than that of the 11-4 or 14-7-1 structures. Finally, under different temperature conditions, many different close-packed structures are identified in the nanowires before they fracture.

scholarly journals Study on Lightweight and Strengthening Effect of Carbon Nanotube in Highly Ordered Nanoporous Nickel: A Molecular Dynamics Study

2019 ◽  
Vol 9 (2) ◽  
pp. 352 ◽  
Author(s):  
Yu Zhou ◽  
Wu-Gui Jiang ◽  
Duo-Sheng Li ◽  
Qing-Hua Qin
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Tensile Modulus ◽  
Md Simulations ◽  
Absorption Capacity ◽  
Atomic Scale ◽  
Strengthening Effect ◽  
Pore Collapse ◽  
Out Of Plane

The mechanical behavior of nanocomposites consisting of highly ordered nanoporous nickel (HONN) and its carbon nanotube (CNT)-reinforced composites (CNHONNs) subjected to a high temperature of 900 K is investigated via molecular dynamics (MD) simulations. The study indicates that, out-of-plane mechanical properties of the HONNs are generally superior to its in-plane mechanical properties. Whereas the CNT shows a significant strengthening effect on the out-of-plane mechanical properties of the CNHONN composites. Compared to pure HONNs, through the addition of CNTs from 1.28 wt‰ to 5.22 wt‰, the weight of the composite can be reduced by 5.83‰ to 2.33% while the tensile modulus, tensile strength, compressive modulus and compressive strength can be increased by 2.2% to 8.8%, 1% to 5.1%, 3.6% to 10.2% and 4.9% to 10.7%, respectively. The energy absorption capacity can also be improved due to the existence of CNTs. Furthermore, the MD simulations provide further insights into the deformation mechanism at the atomic scale, including fracture in tension, pore collapse in compression and local changes in lattice structures due to stacking faults.

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