Molecular Dynamics Simulation Of Thermal Properties Of Cubic Boron Nitride/epoxy Resin Composites

Polymer is widely used in medicine,electrical,chemical and other fields,with irreplaceable role.However,the low thermal conductivity of polymer has greatly limited the application range of polymer.Adding inorganic filler with high thermal conductivity into polymer is considered to be one of the effective methods to improve the thermal conductivity of composite materials.The interfacial thermal resistance between them is a non-negligible factor affecting the thermal conductivity of composites.Therefore,it is of great significance to study and analyze the factors influencing the interfacial thermal resistance between organic matrix and inorganic filler.Based on epoxy resin as matrix,the cubic boron nitride as the inorganic filler,adopt the method of molecular dynamics simulation study to cubic boron nitride doped into epoxy resin matrix after the thermal conductivity of the composites and the influence of glass transition temperature,and inorganic nanoparticles and organic matrix are discussed the coulomb interaction on the interface between the influence of thermal resistance.（1）A structure model of pure epoxy resin with a crosslinking degree of 60%at room temperature and pressure was constructed to verify the model.Then,EMD and NEMD simulation methods were used to calculate the thermal conductivity of pure epoxy resin,and the results were 0.2065W·m^-1K^-1 and 0.2174W·m^-1K^-1,respectively.Prepare for the doping of cubic boron nitride later.（2）The epoxy resin was doped with 10%cubic boron nitride by mass fraction.The thermal conductivity of the composite is 0.2668W·m^-1K^-1 when the coulomb interaction between cubic boron nitride and epoxy resin matrix is not considered.When the coulomb interaction between cubic boron nitride and epoxy matrix is considered,the thermal conductivity of the composite is 0.3017W·m^-1K^-1.The interfacial thermal resistance between cubic boron nitride and epoxy resin matrix with different thicknesses was calculated.It is found that the interfacial thermal resistance decreases with the increase of cubic boron nitride thickness.When the coulomb interaction between c-BN and epoxy resin matrix is considered,the calculated interfacial thermal resistance is less than that without the coulomb interaction between c-BN and epoxy resin matrix at the same thickness.when the thickness ratio of cubic boron nitride is 1:1 and the coulomb interaction between cubic boron nitride and epoxy resin matrix is considered,the interfacial thermal resistance is 4.1568×10^-9m²·KW^-1.（3）The glass transition temperature of composites was calculated by density method and mean azimuth shift method.When the mass fraction of cubic boron nitride is 10%,the glass transition temperature of the composites is calculated by density method and mean orientation shift time method.Compared with pure epoxy resin,the glass transition temperature is increased.The influence of coulomb interaction between c-BN nanoparticles and epoxy matrix on the thermal conductivity and interfacial thermal resistance of the composites was analyzed through the microscopic mechanism.When the coulomb interaction between c-BN and epoxy resin matrix is considered,the interface density of epoxy resin matrix close to c-BN is higher,resulting in stronger interfacial interaction,which leads to lower interfacial thermal resistance and higher thermal conductivity of composites.