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

Abstract

AbstractTo comparatively investigate the mechanical, tribological, and interfacial properties of polytetrafluoroethylene (PTFE) strengthened by graphene (Gr) and hexagonal boron nitride (h‐BN) nanosheets, molecular models of PTFE nanocomposites containing a similar weight fraction of Gr and h‐BN nanosheets were established. The constant‐strain approach, the three‐layer friction structures, and the pull‐out simulations were respectively employed to calculate the mechanical, tribological, and interfacial properties of the nanocomposites. Results indicate that the Young's, shear, and bulk moduli of the nanocomposites are increased by 17.22%, 20.72%, and 4.78%, respectively, by introducing h‐BN nanosheets than those by introducing Gr nanosheets. Meanwhile, a decrease of 8.49% in the friction coefficient of the nanocomposites is obtained by incorporating h‐BN nanosheets than that by incorporating Gr nanosheets. In addition, 84.71% and 5.18 times higher in the interfacial cohesive strength and interfacial shear strength, and 91.58% and 128.7% higher in the interfacial fracture toughness of PTFE nanocomposites in the normal separation and shear separation, respectively, are achieved by incorporating h‐BN nanosheets than those by incorporating Gr nanosheets. To provide a deeper understanding of the enhancement mechanisms of h‐BN nanosheets, the interfacial interaction energies, radial distribution functions, and von Mises stress distributions of the two PTFE nanocomposites were evaluated and interpreted accordingly.