Molecular Simulation Of Tribological Properties Of Carbon Nanotubes Reinforced Nitrile Butadiene Rubber

Screw pump is widely used in the field of oil extraction because of its simple equipment,low cost and no pollution to the environment.Nitrile-butadiene rubber(NBR)is mainly used for screw pump stator,whose performance directly affects the service life of the screw pump.CNTs have gradually replaced traditional reinforcing materials and become an ideal reinforcing agent for a new generation of polymer materials because of its excellent properties.In this paper,Molecular dynamics simulation was used to explore the effects of chirality,diameter and wall number of CNTs on interface binding ability,mechanical properties and tribological properties of NBR matrix.Firstly,the molecular models of CNTs/NBR composites with different tube chirality were established.Pull-out behavior method,constant stress method and restrictive shear method were used to calculate interface binding energy,interfacial shear strength,Elastic modulus,tensile strength,wear rate and friction coefficient of CNTs/NBR composites.The reinforcement mechanism of tube charility on the mechanical properties and tribological properties of NBR matrix was also expounded from the atomic level.The results show that tube charilities have little influence on the interfacial shear strength of composites.(6,4)CNTs have better interfacial binding ability with the NBR matrix because of its unique structure.The structure of composite is more compact and stable.Mechanical properties and tribological properties of NBR matrix are significantly improved.Secondly,the molecular models of CNTs/NBR composites with different tube diameter were established.Interface binding energy,interfacial shear strength,Elastic modulus,tensile strength,wear rate and friction coefficient of CNTs/NBR composites were calculated and compared.The reinforcement mechanism of tube diameter on the mechanical properties and tribological properties of NBR matrix was also expounded from the atomic level.The results show that part of the NBR chains will enter the interior of CNTs while the diameter of CNTs is increasing which causes the deformation of CNTs and affects their reinforcing ability.Due to its smaller diameter,(5,5)CNTs can improve the resistance to elastic deformation of NBR matrix better by maintaining its structural properties.It makes NBR matrix have better mechanical properties and tribological properties.Finally,the molecular models of CNTs/NBR composites with different tube walls were established such as SWCNTs,DWCNTs and TWCNTs.Interface binding energy,interfacial shear strength,Elastic modulus,tensile strength,wear rate and friction coefficient of CNTs/NBR composites were calculated and compared.The reinforcement mechanism of the number of CNTs walls on the mechanical properties and tribological properties of NBR matrix was also expounded from the atomic level.The results show that with the increase of the number of CNTs walls,the number of NBR chains entering the interior of CNTs decreases.The structure of CNTs itself is more stable.The interfacial shear strength and the elastic modulus of CNTs/NBR composites increase.The tensile strength first increase and then decrease.(15,15)(10,10)DWCNTs/NBR composites exhibit better tribological properties.