Molecular Simulation Of The Friction Properties Of Nitrile Rubber And Polyvinyl Chloride Composite System

At present,in the field of oil exploitation,submersible screw pump production system is widely used.The screw pump equipment is simple,low cost and energy consumption,no pollution to the environment,and the installation and operation is very convenient.In recent years,NBR is the main material of screw pump stator.Due to the problems of oil immersion and sand in actual oil production conditions,the wear of stator and rotor is very serious,its wearresisting performance directly determines the lifetime of screw pump.The paper aims to upgrade the wear-resisting property of NBR.Rubber and plastic blending by adding PVC,and SWCNT was added to NBR/PVC blend rubber for reinforcement,the wear-resisting property of stator is upgraded and the overall lifetime of submersible screw pump is lengthened.Molecular dynamics simulation was used in the paper,based on Newton mechanics,statistical mechanics were employed to solve the molecular motion equation,simulate the molecular architecture of the studied materials,and observe the property changes of the composite system from the atomic point of view.In this paper,the compatibility and mechanical performance of NBR/PVC blend rubber with disparate proportions were calculated.It was found that when the blending proportion was 70/30,the compatibility and wear-resisting property of blending rubber were the best.The variation tendency of emulation outcome in the article and experimental data in the literature were roughly unanimous,which fully confirmed the accuracy of molecular dynamics simulation method.This research method economizes a large number of experimental resources and upgrades the efficiency of scientific research.On the basis of 70/30 NBR/PVC blends,SWCNTs with different diameters and orientations were added to reinforce NBR/PVC composites,and the amorphous molecular model of SWCNT reinforced NBR/PVC composites was established.By calculating the mechanical performance and mean square displacement of the composite system,it is concluded that the elastic modulus of the composite system increases the most,and the hardness and resistance to deformation are greatly improved after adding SWCNT with diameter of 6.78(?);when the orientation of SWCNT is 90°in the composite system,material hardness increases by 60%,the modulus is also enhanced,the reinforcing effect is very good.In order to fully study the change of wear resistance of the composite system,the metal friction pair model of the composite system was constructed.Through the calculation of the restricted shear simulation and radial distribution function,it was found that the wear rate of the composite material declined by 46.77%,and the wear resistance increased to a great extent after adding single-walled carbon nanotubes with diameter of 6.78(?);From the atomic point of view,when the orientation of SWCNT is 90°in the composite system,SWCNT has strong adsorption performance and strong van der Waals force on the surface,adsorbing a large number of NBR and PVC molecular chains,which makes the rubber matrix very stable.During the course of friction,the superficies matter falls out less,the wear-resisting property of the composite material is better.