scholarly journals Molecular dynamics simulation to enhance the mechanical and tribological properties of polyimide composites by graphene reinforcement

2021 ◽  
Vol 2083 (2) ◽  
pp. 022107
Author(s):  
Zhe Chen ◽  
Aijiao Li ◽  
Hong Liu

Abstract Background: Polyimide is one of the organic polymer materials with the best comprehensive performance. It has outstanding mechanical properties, excellent thermal stability and excellent corrosion resistance, but pure polyimide has high coefficient of friction and wear rate. By combining graphene with polyimide, the mechanical properties of the composite are significantly reformatived, and the friction coefficient and wear rate can be reduced. Objective: The molecular models were developed to study the mechanical and tribological properties of graphene as a reinforced material. Methods: In this paper, the mechanical properties and friction and wear mechanism of materials are studied by molecular dynamics method from the microscopic point of view. The Young’s modulus and hardness of composites were calculated using the strain constant method. Results: Molecular dynamics simulation results expressed that the Young’s modulus and hardness of polymer composites benefited by approximately 115% and 42%, respectively, after the addition of the graphene-reinforced material. The average friction coefficient and wear rate of polymer composites fall by 35% and 48%, respectively. Through the calculation and statistics of the micro-information in the process of friction simulation, the internal mechanism of various situations is revealed in the atomic dimension. Conclusions: Graphene can adsorb on the surface of polymer chain segment, a strong polymer matrix, through van der Waals and electrostatic forces and can effectively resist external loading.

RSC Advances ◽  
2014 ◽  
Vol 4 (22) ◽  
pp. 11475-11480 ◽  
Author(s):  
Yao-Chun Wang ◽  
Shin-Pon Ju ◽  
Chien-Chia Chen ◽  
Hsin-Tsung Chen ◽  
Jin-Yuan Hsieh

Molecular dynamics (MD) simulation was used to investigate the mechanical properties of several starch composites.


2021 ◽  
Author(s):  
Xueshen Liu ◽  
Xincong Zhou ◽  
Fuming Kuang ◽  
Houxiu Zuo ◽  
Jian Huang

Abstract This paper investigated the mechanism of enhancing the mechanical and tribological properties of nitrile rubber (NBR) with SiO 2 on the molecular scale. Molecular dynamics (MD) simulations were performed on molecular structure models of pure NBR, NBR/SiO 2 and three-layer friction pairs. The results showed that the hydrogen bonds and interfacial interaction between SiO 2 and NBR molecular chains decreased the fractional free volume of NBR nanocomposites, and increased the shear modulus of NBR by 25% compared with that of pure NBR. During the friction process, SiO 2 decreased the radius of gyration of NBR molecular chains and effectively lowered the peak atomic velocity, the peak temperature and the peak friction stress at the interface between NBR and copper atoms. The average friction stress on NBR/SiO 2 was 34% lower than that on NBR, which meant the tribological properties of NBR were significantly improved by SiO 2 . The mechanism of SiO 2 reinforcing NBR on a molecular scale can lay a theoretical foundation for the design of water-lubricated rubber bearings.


2010 ◽  
Vol 654-656 ◽  
pp. 2763-2766 ◽  
Author(s):  
Li Wen Mu ◽  
Xin Feng ◽  
Yi Jun Shi ◽  
Huai Yuan Wang ◽  
Xiao Hua Lu

The tribological properties of polyimide (PI) composites reinforced with graphite or MoS2 sliding in liquid alkali and water as well as dry friction were investigated using a ring-on-ring tester. The results show that the friction coefficient (μ) and wear rate (W) for both graphite/PI and MoS2/PI composites in different liquid mediums are μdry>μwater >μalkali and Wwater>Wdry >Walkali. Results also indicate that the friction coefficient and wear rate of the PI composites filled with different solid lubricants are μMoS2 >μgraphite and W MoS2 >Wgraphite in different liquid mediums. In addition, the hydrophobic inorganic fillers are fit for the reinforcement of polymer-based composites sliding in liquid mediums. It is also concluded from the authors’ work that the wear rate and friction coefficient of polymer-based (such as PI, PTFE) composites in the alkali lubricated conditions is lowest among all the friction conditions. This may be attributed to the ionic hydration in the alkaline solution.


2011 ◽  
Vol 378-379 ◽  
pp. 7-10
Author(s):  
Gui Xue Bian ◽  
Yue Liang Chen ◽  
Jian Jun Hu ◽  
Li Xu

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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