Molecular Dynamics Simulation Of Structure And Properties Of Hydrogenated Nitrile Butadiene Rubber

Nanopolymers are important products in the petrochemical and chemical industries and are widely used in the automotive industry,aerospace and other fields.Hydrogenated nitrile rubber（HNBR）is a highly saturated nano-polymer material with excellent mechanical properties and corrosion resistance to meet its application needs in complex working conditions.The aim of this paper is to reveal the microscopic mechanism of enhancing the performance of HNBR from the microstructure and to explore the methods to optimize the thermal properties of HNBR（1）The effect of acrylonitrile content on the mechanical and thermal properties of HNBR was investigated.Firstly,based on the actual production process of HNBR,the models of HNBR with different degrees of polymerisation were constructed,and the optimum degree of the model was determined to be 50 using density and solubility parameters.Secondly,the HNBR models with different acrylonitrile content were established and it was found that the increase of acrylonitrile content would enhance the polarity of the rubber,increase the intermolecular chain force and optimize the mechanical properties of the material,but at the same time,it would reduce the flexibility of the molecular chain and deteriorate the thermal conductivity and low temperature resistance.Finally,by studying the energy change of the system during the glass transition,it was found that bond energy and dihedral angle torsion energy play an important role in the glass transition of HNBR.（2）The effects of carboxyl group introduction and chemical modification on the thermal and adsorption properties of HNBR materials were investigated.Firstly,the model of HNBR and hydrogenated carboxyl nitrile rubber（HXNBR）with the same acrylonitrile content were constructed,and it was found that the introduction of carboxyl groups enhanced the mechanical properties and reduced the low temperature resistance and thermal conductivity of the materials.Secondly,the effects of C₅H₁₁OH,C₁₀H₂₁OH,C₁₅H₃₁OH,C₂₀H₄₁OH and C₂₅H₅₁OH grafting on the thermal properties and Fe wall adsorption properties of HXNBR were analysed.The mechanical properties of the material weaken and then increase as the length of the grafted side chain increases,while the thermal conductivity,low temperature resistance and Fe wall adsorption properties increase and then decrease.The C₂₀H₄₁OH grafted HXNBR has the best thermal properties and adsorption property.（3）The effect of tensile strain on the thermal conductivity of HNBR was investigated.Firstly,the uniaxial tensile process of HNBR material was simulated.The change of thermal conductivity during the tensile process was analyzed.It was found that stretching affects the orientation of the material and expands the free range of phonons,which in turn causes the material to exhibit significant anisotropy,with the thermal conductivity increasing significantly along the direction of stretching and decreasing significantly perpendicular to the direction of stretching.Secondly,the effects of stretching temperature and stretching rate on the thermal conductivity of HNBR were analysed.The thermal conductivity was found to increase and then decrease as both the stretching temperature and rate increased,which was related to the orientation of the system and phonon thermal transport.In the process of research,molecular dynamics methods were used to simulate the material properties from the perspectives of molecular structure and properties,modified HNBR and tensile strain to improve material orientation,etc.The results of the study are a guide to optimize the performance of HNBR...