Molecular dynamics study on enhancement of mechanical and tribological properties of polytetrafluoroethylene composites by incorporating hexagonal boron nitride nanosheets

Abstract

Molecular models and sandwiched friction models of pure PTFE and h-BN/ PTFE composite were respectively constructed to investigate the enhancement of mechanical and tribological performances of the polytetrafluoroethylene (PTFE) matrix by incorporating the hexagonal boron nitride (h-BN) nanosheets as reinforcements. The simulation results indicate that increases of 36.4% in the Young's modulus, 23.6% in the bulk modulus, and 37.3% in the shear modulus of the PTFE matrix are achieved respectively by the incorporation of h-BN nanosheets. Decreases of 3.48% and 10.27% in the Poisson's ratio and the ratio of bulk modulus to shear modulus of the PTFE matrix are also observed due to the incorporation of h-BN nanosheets, which shows that the ductility of the PTFE matrix could be somewhat decreased with the addition of h-BN nanosheets. Additionally, decreases of 69.23% and 69.06% in the coefficient of friction and friction stress of the PTFE matrix are obtained respectively with the introduction of h-BN nanosheets. To provide in-depth insight into the internal reason for these findings, the interaction energy between the PTFE matrix and h-BN nanosheets, the MSD and diffusion coefficient of PTFE chains, and the RDF of carbon and fluorine atoms in the PTFE backbone chains were evaluated and interpreted accordingly.

Enhanced mechanical and tribological properties of polymer nanocomposites by improving interfacial properties by hexagonal boron nitride nanosheets: Molecular dynamics simulations

“…29 From Figure 4, the Young's moduli of the Gr/PTFE and h-BN/PTFE composites are obtained to be 2.09 and 2.45 GPa, respectively, which are in good agreement with the previous MD study. 16,30 It is indicated that an increment of 17.22% in the Young's modulus of the PTFE nanocomposites is obtained by the introduction of h-BN nanosheets as reinforcements than by the introduction of Gr nanosheets. Moreover, the shear moduli of the nanocomposites reinforced by Gr and h-BN nanosheets are respectively calculated to be 1.11 and 1.34 GPa.…”

“…It was proven by previous studies that an adsorption can be observed between Gr or h-BN nanosheets and polymer chains due to the presence of the interfacial interactions. 16,[31][32][33] It can be inferred that h-BN nanosheets are able to provide better interfacial interaction properties to resist external loads, resulting in better mechanical enhancement than Gr nanosheets. It is widely known that the mechanical properties of polymers have a significant impact on their tribological properties.…”

“…To investigate the tribological properties of PTFE composites reinforced by Gr and h-BN nanosheets, the three-layer friction models shown in Figure 2a,b were employed to calculate the friction coefficients of the two PTFE composites. The friction coefficient and bond orientation parameters were obtained based on our previous simulation study, 16 and the results are shown in Figure 5. Figure 5a shows the variations of friction coefficients of the two PTFE composites with shearing time.…”

“…It was found that Gr nanosheets could provide stronger reinforcements than CNTs due to the stronger interfacial interactions provided by the specific 2D structure. Yang et al 16 employed MD simulations to study the enhanced mechanical and tribological properties of PTFE nanocomposites by incorporating h-BN nanosheets as reinforcements. Nevertheless, there is still very little MD work to elucidate the inherent mechanisms of Gr, h-BN/polymer nanocomposites at the atomic level.…”

Analysis of static and dynamic mechanical properties of carbon black/carbon nanotubes hybrid filled natural rubber nanocomposites using coarse‐grained molecular dynamics

“…In contrast, molecular dynamics (MD) simulations provide detailed information for the design and exploration of polymer nanocomposites through bottom-up prediction. [12][13][14][15] In order to further extend the temporal and spatial scales of MD simulations, the coarse-grained molecular dynamics (CGMD) simulations have been developed and widely used to study the mechanical performances of the NP-filled polymer composites. Yuan et al 16,17 constructed the CG force fields for the CB-and silica-filled NR nanocomposites using hybrid iterative Boltzmann inversion (IBI) [18][19][20] and effective force coarsegraining (EFCG) 21 methods, and then investigated the tensile behavior of silica-filled NR nanocomposites and the viscoelastic behavior of CB/silica hybrid NPs filled NR nanocomposites, respectively.…”