Mechanical and Tribological Properties of Nitrile Rubber Reinforced by Nano-SiO2: Molecular Dynamics Simulation

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 signi cantly 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.

Mechanical and tribological properties of polytetrafluoroethylene reinforced by nano-ZrO2: Molecular dynamic simulation

“…The tribological characteristics could be analyzed from the trajectory file, which was obtained by the Confined Shear module. 31–33 The friction coefficient was calculated by dividing the friction force by the normal load.

Figure 2.Tribological model with a three-layer molecular structure.

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“…The 5-cycle anneal process was implemented from 300 K to 700 K. The stable tribological model of PTFE and PTFE/ZrO 2 is illustrated in The tribological characteristics could be analyzed from the trajectory file, which was obtained by the Confined Shear module. [31][32][33] The friction coefficient was calculated by dividing the friction force by the normal load.…”

“…To realize the tribological process of Cu counterpart and polymer composites, a relative slip velocity of 0.1 Å/ps was given to the upper Cu atom under NVT ensemble for 500 ps. The tribological characteristics could be analyzed from the trajectory file, which was obtained by the Confined Shear module [31][32][33]. The friction coefficient was calculated by dividing the friction force by the normal load.…”

Enhanced Tribological Properties of Vulcanized Natural Rubber Composites by Applications of Carbon Nanotube: A Molecular Dynamics Study

“…Double layer and three-layer models were developed to study the interfacial proper ties and tribological performance. These models were constituted of CNT/VNR model an The geometry optimization was applied to crosslinked CNT/VNR model by conjugate gradient method with the energy and force convergence tolerance of 1 × 10 −5 kcal/mol and 5 × 10 −4 kcal/mol/Å [61]. Then, a 100ps 5-cycle annealing process was conducted constant volume and temperature (NVT ensemble) from 200 K to 400 K to relax the internal stress of the structure.…”

“…The accuracy and buffer width of Ewald method were 1 × 10 −5 kcal/mol and 0.5 Å . The cutoff distance, spline width and buffer width of van der Waals interaction calculations were 18.5 Å , 1 Å and 0.5 Å [61]. Additionally, all atoms of SiO 2 layer needs to be unfixed before the calculation.…”