Molecular dynamics predictions of thermomechanical properties of an epoxy thermosetting polymer

Fan, Jiadi; Anastassiou, Alexandros; Macosko, Christopher W.; Tadmor, Ellad B.

doi:10.1016/j.polymer.2020.122477

Cited by 59 publications

(46 citation statements)

References 61 publications

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“…With the increase of degree of cross-linking, the rearrangement ability of the epoxy polymer was weakened under the external load. The higher the degree of cross-linking, the greater the polarity and the stronger the interaction between the chains [ 34 ]. As a result, Young’s modulus and the yield stress increased.…”

Section: Resultsmentioning

confidence: 99%

“…Their results showed that the epoxy Young’s modulus was less dependent on strain rate below T g. Therefore, as shown in Table 2 , Young’s moduli of the epoxy polymer with degree of cross-linking of 85.4% calculated at 300 K was close to the experiment and other simulation results. However, the yield strength was greatly affected by strain rate [ 34 ]. As shown in Table 2 , the yield strength of the system with a degree of cross-linking of 85.4% was close to other simulation results and experimental values.…”

Section: Resultsmentioning

confidence: 99%

“…Most of the methods have been found to produce only a small difference on the results of thermal-mechanical properties [ 33 ]. Among them, a multi-step cross-linking approach is widely used [ 22 , 26 , 34 ]. This approach searches for atoms that can participate in the cross-linking reaction by gradually increasing the cut-off radius.…”

Section: MD Simulation Methodologymentioning

confidence: 99%

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Molecular Dynamics Investigation of the Thermo-Mechanical Properties of the Moisture Invaded and Cross-Linked Epoxy System

Sheng

Sun

et al. 2021

Polymers

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In spite of a high market share of plastic IC packaging, there are still reliability issues, especially for the effects of moisture. The mechanism between moisture and epoxy polymer is still obscure. A multi-step cross-linking approach was used to mimic the cross-linking process between the DGEBA resin and JEFFAMINE®-D230 agent. Based on the molecular dynamics method, the thermo-mechanical properties and microstructure of epoxy polymer were analyzed. In this paper, the degree of cross-linking ranged from 0% to 85.4% and the moisture concentration ranged from 0 wt.% to 12 wt.%. The hydrogen bonds were investigated in the moisture invaded epoxy polymer. Although most of the hydrogen bonds were related to water molecules, the hydrogen bonds between the inside of epoxy polymer were reduced only a little as the concentration of moisture increased. The diffusion coefficient of the water molecules was found to increase with the increase of moisture concentration. When the moisture concentration was larger than 12 wt.% or smaller than 1.6 wt.%, the diffusion coefficient was less affected by the epoxy polymer. In addition, the free volume and the thermal conductivity of the epoxy polymer were considered. It was found that the moisture could increase the thermal conductivity from 0.24 to 0.31 W/m/K, identifying a coupling relationship between moisture and thermal properties. Finally, the mechanical properties of epoxy polymer were analyzed by uniaxial tensile simulation. The COMPASS and DREIDING force fields were used during the uniaxial tensile simulation. A better result was achieved from the DREIDING force field compared with the experiment. The degree of cross-linking was positively correlated with mechanical properties. For the system with the largest degree of cross-linking of 85.4%, the Young’s modulus was 2.134 ± 0.522 GPa and the yield strength was 0.081 ± 0.01 GPa. There were both plasticizing and anti-plasticizing effects when the water molecules entered the epoxy polymer. Both the Young’s moduli and yield strength varied in a large range from 1.38 to 2.344 GPa and from 0.062 to 0.128 GPa, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: MD Simulation Methodologymentioning

confidence: 99%

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Molecular Dynamics Investigation of the Thermo-Mechanical Properties of the Moisture Invaded and Cross-Linked Epoxy System

Sheng

Sun

et al. 2021

Polymers

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“…Molecular dynamics simulations (MD) have become a useful tool for clarifying the causes of experimental phenomena [19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Regarding the mechanical properties of polymers, Fan et al predicted the thermomechanical properties of epoxy [19] and Fujimoto et al investigated the impact fracture of poly-methyl-methacrylate (PMMA) and polycarbonate (PC) [20].…”

Section: Introductionmentioning

confidence: 99%

A Possibility for Quantitative Detection of Mechanically-Induced Invisible Damage by Thermal Property Measurement via Entropy Generation for a Polymer Material

et al. 2022

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Entropy generation from a mechanical and thermal perspective are quantitatively compared via molecular dynamic (MD) simulations and mechanical and thermal experiments. The entropy generation values regarding mechanical tensile loading—which causes invisible damage—of the Polyamide 6 (PA6) material are discussed in this study. The entropy values measured mechanically and thermally in the MD simulation were similar. To verify this consistency, mechanical and thermal experiments for measuring entropy generation were conducted. The experimentally obtained mechanical entropy was slightly less than that calculated by MD simulation. The thermal capacity is estimated based on the specific heat capacity measured by differential scanning calorimetry (DSC), applying the assumed extrapolation methods. The estimated entropy generation was higher than the aforementioned values. There is a possibility that the entropy-estimating method used in this study was inappropriate, resulting in overestimations. In any case, it is verified that entropy increases with mechanical loading and material invisible damage can be qualitatively detected via thermal property measurements.

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“…In recent years, with the development of high-performance computing technology, molecular dynamics (MD) simulation has been widely used in the study of the microstructure and macro-properties of composite polymer materials [ 25 , 26 ]. MD simulation can build materials on the atomic scale, which greatly reduces the manufacturing cost and development cycle and then simulates the structure and behavior of molecules to calculate the properties of the materials [ 27 , 28 ]. At present, many studies have been conducted on the properties of nanocomposite epoxy resins, using MD simulation [ 29 , 30 , 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester

Zhang

Wang

et al. 2021

Polymers

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To study the effect of hyperbranched polyester with different kinds of terminal groups on the thermomechanical and dielectric properties of silica–epoxy resin composite, a molecular dynamics simulation method was utilized. Pure epoxy resin and four groups of silica–epoxy resin composites were established, where the silica surface was hydrogenated, grafted with silane coupling agents, and grafted with hyperbranched polyester with terminal carboxyl and terminal hydroxyl, respectively. Then the thermal conductivity, glass transition temperature, elastic modulus, dielectric constant, free volume fraction, mean square displacement, hydrogen bonds, and binding energy of the five models were calculated. The results showed that the hyperbranched polyester significantly improved the thermomechanical and dielectric properties of the silica–epoxy composites compared with other surface treatments, and the terminal groups had an obvious effect on the enhancement effect. Among them, epoxy composite modified by the hyperbranched polyester with terminal carboxy exhibited the best thermomechanical properties and lowest dielectric constant. Our analysis of the microstructure found that the two systems grafted with hyperbranched polyester had a smaller free volume fraction (FFV) and mean square displacement (MSD), and the larger number of hydrogen bonds and greater binding energy, indicating that weaker strength of molecular segments motion and stronger interfacial bonding between silica and epoxy resin matrix were the reasons for the enhancement of the thermomechanical and dielectric properties.

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Molecular dynamics predictions of thermomechanical properties of an epoxy thermosetting polymer

Cited by 59 publications

References 61 publications

Molecular Dynamics Investigation of the Thermo-Mechanical Properties of the Moisture Invaded and Cross-Linked Epoxy System

Molecular Dynamics Investigation of the Thermo-Mechanical Properties of the Moisture Invaded and Cross-Linked Epoxy System

A Possibility for Quantitative Detection of Mechanically-Induced Invisible Damage by Thermal Property Measurement via Entropy Generation for a Polymer Material

Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester

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