scholarly journals The Mechanical Properties of Poly (Urea-Formaldehyde) Incorporated with Nano-SiO2 by Molecular Dynamics Simulation

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1447
Author(s):  
Yanfang Zhang ◽  
Youyuan Wang ◽  
Yudong Li ◽  
Zhanxi Zhang
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Urea Formaldehyde ◽  
Interfacial Interaction ◽  
Dynamics Simulation ◽  
Self Healing ◽  
Fractional Free Volume ◽  
Sio2 Surface ◽  
Nano Sio2

Self-healing materials can promote the sustainable reuse of resources. Poly (urea-formaldehyde) (PUF) microcapsules can be incorporated into dielectric materials for self-healing. However, the mechanical properties of PUF microcapsules need to be improved due to insufficient hardness. In this paper, PUF models incorporated with nano-SiO2 of different filler concentrations (0, 2.6, 3.7, 5.3, 6.7, 7.9 wt.%) were designed. The density, the fractional free volume, and the mechanical properties of the PUF-SiO2 models were analyzed at an atomic level based on molecular dynamics simulation. The interfacial interaction model of PUF on the SiO2 surface was also constructed to further investigate the interaction mechanisms. The results showed that the incorporation of nano-SiO2 had a significant effect on the mechanical properties of PUF. Density increased, fractional free volume decreased, and mechanical properties of the PUF materials were gradually enhanced with the increase of nano-SiO2 concentration. This trend was also confirmed by experimental tests. By analyzing the internal mechanism of the PUF–SiO2 interfacial interaction, it was found that hydrogen bonds play a major role in the interaction between PUF and nano-SiO2. Moreover, hydrogen bonds can be formed between the polar atoms of the PUF chain and the hydroxyl groups (–OH) as well as O atoms on the surface of SiO2. Hydrogen bonds interactions are involved in adsorption of PUF chains on the SiO2 surface, reducing the distance between PUF chains and making the system denser, thus enhancing the mechanical properties of PUF materials.

scholarly journals Molecular Dynamics Study on Mechanical Properties of Interface between Urea-Formaldehyde Resin and Calcium-Silicate-Hydrates

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4054
Author(s):  
Xianfeng Wang ◽  
Wei Xie ◽  
Taoran Li ◽  
Jun Ren ◽  
Jihua Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Calcium Silicate ◽  
Urea Formaldehyde ◽  
Dynamics Simulation ◽  
Cement Matrix ◽  
Formaldehyde Resin ◽  
Self Healing ◽  
Binding Behavior ◽  
Composite Models

Microcapsule based self-healing concrete can automatically repair damage and improve the durability of concrete structures, the performance of which depends on the binding behavior between the microcapsule wall and cement matrix. However, conventional experimental methods could not provide detailed information on a microscopic level. In this paper, through molecular dynamics simulation, three composite models of Tobermorite (Tobermorite 9 Å, Tobermorite 11 Å, Tobermorite 14 Å), a mineral similar to Calcium-Silicate–Hydrate (C–S–H) gel, with the linear urea–formaldehyde (UF), the shell of the microcapsule, were established to investigate the mechanical properties and interface binding behaviour of the Tobermorite/UF composite. The results showed that the Young’s modulus, shear modulus and bulk modulus of Tobermorite/UF were lower than that of ‘pure’ Tobermorite, whereas the tensile strength and failure strain of Tobermorite/UF were higher than that of ‘pure’ Tobermorite. Moreover, through radial distribution function (RDF) analysis, the connection between Tobermorite and UF found a strong interaction between Ca, N, and O, whereas Si from Tobermorite and N from UF did not contribute to the interface binding strength. Finally, high binding energy between the Tobermorite and UF was observed. The research results should provide insights into the interface behavior between the microcapsule wall and the cement matrix.

Molecular dynamics simulation insight into the temperature dependence and healing mechanism of an intrinsic self-healing polyurethane elastomer

2020 ◽  
Vol 22 (31) ◽  
pp. 17620-17631
Author(s):  
Xianling Chen ◽  
Jing Zhu ◽  
Yanlong Luo ◽  
Jun Chen ◽  
Xiaofeng Ma ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Hydrogen Bonds ◽  
Molecular Diffusion ◽  
Healing Process ◽  
The Self ◽  
Dynamics Simulation ◽  
Polyurethane Elastomer ◽  
Self Healing ◽  
Insight Into

The changes in the type and number of hydrogen bonds as well as the microscopic behavior of molecular diffusion in the self-healing process of polyurethane are revealed.

scholarly journals Micro-Structure and Thermomechanical Properties of Crosslinked Epoxy Composite Modified by Nano-SiO2: A Molecular Dynamics Simulation

Polymers ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 801 ◽  
Author(s):  
Qing Xie ◽  
Kexin Fu ◽  
Shaodong Liang ◽  
Bowen Liu ◽  
Lu Lu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Particle Size ◽  
Rational Design ◽  
Thermomechanical Properties ◽  
Composite Model ◽  
Dynamics Simulation ◽  
Thermal And Mechanical Properties ◽  
Micro Structure ◽  
Nano Sio2

Establishing the relationship among the composition, structure and property of the associated materials at the molecular level is of great significance to the rational design of high-performance electrical insulating Epoxy Resin (EP) and its composites. In this paper, the molecular models of pure Diglycidyl Ether of Bisphenol A resin/Methyltetrahydrophthalic Anhydride (DGEBA/MTHPA) and their nanocomposites containing nano-SiO2 with different particle sizes were constructed. The effects of nano-SiO2 dopants and the crosslinked structure on the micro-structure and thermomechanical properties were investigated using molecular dynamics simulations. The results show that the increase of crosslinking density enhances the thermal and mechanical properties of pure EP and EP nanocomposites. In addition, doping nano-SiO2 particles into EP can effectively improve the properties, as well, and the effectiveness is closely related to the particle size of nano-SiO2. Moreover, the results indicate that the glass transition temperature (Tg) value increases with the decreasing particle size. Compared with pure EP, the Tg value of the 6.5 Å composite model increases by 6.68%. On the contrary, the variation of the Coefficient of Thermal Expansion (CTE) in the glassy state demonstrates the opposite trend compared with Tg. The CTE of the 10 Å composite model is the lowest, which is 7.70% less than that of pure EP. The mechanical properties first increase and then decrease with the decreasing particle size. Both the Young’s modulus and shear modulus reach the maximum value at 7.6 Å, with noticeable increases by 12.60% and 8.72%, respectively compared to the pure EP. In addition, the thermal and mechanical properties are closely related to the Fraction of Free Volume (FFV) and Mean Squared Displacement (MSD). The crosslinking process and the nano-SiO2 doping reduce the FFV and MSD value in the model, resulting in better thermal and mechanical properties.

scholarly journals Molecular Dynamics Simulation on the Interaction between Palygorskite Coating and Linear Chain Alkane Base Lubricant

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 286
Author(s):  
Jin Zhang ◽  
Lv Yang ◽  
Yue Wang ◽  
Huaichao Wu ◽  
Jiabin Cai ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Structural Changes ◽  
Molecular Diffusion ◽  
Linear Chain ◽  
Interfacial Interaction ◽  
Dynamics Simulation ◽  
Electrostatic Energy ◽  
Experimental Development ◽  
Practical Applications ◽  
Self Diffusion

Molecular dynamics (MD) simulations were conducted to investigate the interactions between a palygorskite coating and linear chain alkanes (dodecane C12, tetradecane C14, hexadecane C16, and octadecane C18), representing base oils in this study. The simulation models were built by placing the alkane molecules on the surface of the palygorskite coating. These systems were annealed and geometrically optimized to obtain the corresponding stable configurations, followed by the analysis of the structural changes occurring during the MD process. The interfacial interaction energies, mean square displacements, and self-diffusion coefficients of the systems were evaluated to characterize the interactions between base lubricant molecules and palygorskite coating. It was found that the alkanes exhibited self-arrangement ability after equilibrium. The interfacial interaction was attractive, and the electrostatic energy was the main component of the binding energy. The chain length of the linear alkanes had a significant impact on the intensity of the interfacial interactions and the molecular diffusion behavior. Moreover, the C12 molecule exhibited higher self-diffusion coefficient values than C14, C16 and C18. Therefore, it could be the best candidate to form an orderliness and stable lubricant film on the surface of the palygorskite coating. The present work provides new insight into the optimization of the structure and composition of coatings and lubricants, which will guide the experimental development of these systems for practical applications.

Molecular Dynamics Simulation of Crack Initiation of Aluminum under Tensile Deformation

2011 ◽  
Vol 378-379 ◽  
pp. 7-10
Author(s):  
Gui Xue Bian ◽  
Yue Liang Chen ◽  
Jian Jun Hu ◽  
Li Xu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Elastic Constants ◽  
Tensile Deformation ◽  
Crack Nucleation ◽  
Tensile Load ◽  
Dynamics Simulation ◽  
Metal Aluminum ◽  
Impurity Metal

Molecular dynamics simulation was used to simulate the tension process of purity and containing impurity metal aluminum. Elastic constants of purity and containing impurity metal aluminum were calculated, and the effects of impurity on the elastic constants were also studied. The results show that O-Al bond and Al-Al bond near oxygen atoms could be the sites of crack nucleation or growth under tensile load, the method can be extended to research mechanical properties of other metals and alloys structures.

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