A study on tribology of nitrile-butadiene rubber composites by incorporation of carbon nanotubes: Molecular dynamics simulations

A three-layer molecular model containing Fe atoms as the top and bottom layers and polymer and carbon nanotube matrix as the core is developed and investigated to provide understandings of the improved tribology properties of the polymer composites by incorporation of carbon nanotubes as reinforcements. The investigation is conducted using molecular dynamics simulations to particularly examine the atomic motions at the friction interface region between Fe atoms and the polymer matrix by applying shear loading to the top and bottom Fe layers. The simulation results indicate that an increase up to 60% in shear modulus of the composites is achieved by introduction of carbon nanotubes. In addition, it is found that after incorporation of carbon nanotubes to the composites, the atom concentration, the peak temperature and atom movement velocities, the average cohesive energy in the friction interface region between polymer matrix and Fe layers, and the average friction stress of the Fe layers are all decreased leading to the improved tribology properties. The research provides a way of understanding how carbon nanotubes can enhance the tribology properties of polymer composites from an atomic point of view.