Molecular Simulation On Reinforcement Of The Mechanical And Friction Properties In Nitrile Butadiene Rubber By Adding Zirconium Dioxide

The electrical submersible motor driven progressive cavity pumping,as a mechanical equipment used to extract oil widely,has the advantages of stable pumping,low energy consumption.Nitrile butadiene rubber（NBR）is the main stator rubber material,the stator rubber is one of the most important parts in system,the rotor of the metal mesh with each other in the extrusion deformation and crude oil mixed with sand and so on multi-factor coupling production environment,this means that the mechanical and tribological properties of rubber directly influnence the service life of the pump.Firstly,the impact of acrylonitrile content on the performance of acrylonitrile-butadiene rubber was studied,and then zirconium dioxide（ZrO₂）was added to the rubber as a reinforcing system to improve the mechanical and tribological properties of rubber,and increase the operating life of oil extraction by the pump.In this paper,three NBR models with different acrylonitrile content were constructed and their mechanical and tribological properties were calculated.The mean square displacement,friction temperature and other micro parameters of the system were calculated.With the increase of polar groups in acrylonitrile of NBR component,the interaction force between NBR chain becomes larger,which limits the activity of molecular chain.When the acrylonitrile content in NBR matrix is 39%,the rubber has the best mechanical properties and the strongest shear power.The simulation results are in keeping with the data,which demonstrates the accuracy of molecular dynamics.The molecular model of ZrO₂/NBR composite system was established by adding different contents of ZrO₂ into the NBR matrix containing 39%acrylonitrile,the mechanical and tribological properties of the system were worked out.By calculating the interfacial binding energy and radial distribution function,More NBR chains are bound to ZrO₂ because of the action of van der Waals force,the intermolecular diffusion in the composite system becomes weaker and weaker.However,when the addition amount of ZrO₂ is too high,the binding ability between reinforcing agent and matrix will be reduced,and the stress transfer will be poor.When ZrO₂ with 20%mass fraction is added to NBR matrix.The comprehensive mechanical properties of ZrO₂ are the best,the abrasion loss and friction coefficient of the NBR matrix reinforced by ZrO₂ with 20%mass fraction are the smallest,the theoretical basis is provided for the selection of adding different forms of ZrO₂ reinforcing agent into the matrix.Three ZrO₂/NBR composite systems with 20%mass fraction of external filling,in-situ filling and in-situ filling and coupling treatment were established,comparing and analysising their mechanical and tribological properties.In which the ZrO₂ matrix reinforced by in-situ filling and coupling treatment was the best,and the modulus of mechanical properties increased mostly.Secondly,To compare the friction coefficient and abrasion loss of the composite materials.The in-situ filling and coupling treatment of ZrO₂ enhanced the wear resistance of NBR matrix,and the calculation results of mechanical and tribological properties were consistent with the experimental data.And further analysis ZrO₂ composite system from micro angle,and calculate interfacial binding energy of the system,due to the complex system hydrogen bonds formed in situ ZrO₂ filled in the heads of the dipole interaction,on the basis of further enhance coupling agent,weakened the intermolecular diffusion activity of matrix,the ZrO₂ bonded with NBR matrix more closely,improved the performance of stator rubber,thus prolonging the service life of the pump.