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Styrene-butadiene rubber is a copolymer widely used in making car tires and has excellent abrasion resistance. The Young's modulus and tribology of pure styrene butadiene rubber (SBR) polymer and carbon nanotube reinforced polymer composites have been investigated using molecular dynamics simulations. The mechanism of enhanced tribology properties using carbon nanotube has been studied and discussed. The obtained Young's modulus shows the enhancement in mechanical properties of SBR polymer when carbon nanotubes are used as reinforcement. The concentration, temperature and velocity profiles, radial distribution function, frictional stresses, and cohesive energy density are calculated and analyzed in detail. The Young's modulus of SBR matrix increases about 29.16% in the presence of the 5% CNT. The atom movement velocity and average cohesive energy density in the friction area of pure SBR matrix was found to be more than that of the CNT/SBR composite. Graphical abstract Initial and final conditions of (a) pure SBR matrix and (b) CNT/SBR matrix subjected toshear loading and frictional stresses of top Fe layers of both pure SBR and CNT/SBR composite.

Graphene reinforced natural rubber composites are developed to study the improvement in mechanical and tribological properties of natural rubber by the introduction of graphene as reinforcement. Constant strain minimization method has been applied to calculate Young’s and shear modulus of developed structures. A three-layer model containing Fe (Iron) atoms at the top and bottom and polymer matrices in the middle has been constructed to calculate the tribological properties. A shear loading is applied to the top iron nanorod by sliding it to the surface of the polymer matrices for 600 ps with a velocity of 0.01 nm/ps. The results show the increase of 185% in Young’s modulus, 32% in shear modulus and 48% in hardness by reinforcing natural rubber with single-layer graphene oxide sheet, respectively. Also, reduction of 28% and 36% in the friction coefficient and abrasion rate obtained by the introduction of graphene oxide sheet in natural rubber matrix. Also, interaction energy between graphene and natural rubber, the angle, bond and kinetic energy of the polymer and composites has been calculated and discussed.

A computational method based on molecular dynamics simulation has been used to investigate the tribological behavior of carbon nanotube reinforced styrene-butadiene rubber. A three-layer molecular model in which top and bottom layers with Fe atoms and core with styrene-butadiene rubber matrices have been designed. The effect of sliding velocities from 1 m/s to 11 m/s has been studied at an applied normal loading. The properties predicted are abrasion rate and coefficient of friction. The average values of coefficient of friction and abrasion rate decrease from 0.451 to 0.328 and 21.16 to 16.5%, respectively, under sliding velocities of 1 m/s to 11 m/s. The molecular dynamics results show the decrease in coefficient of friction and abrasion rates with increasing sliding velocity.