Study Of The Influence Of Interface On Heat Transfer In Nanocomposite

Macromolecular polymers have the characteristics of light weight,good mechanical properties,excellent electrical insulation properties and low preparation costs,and can be widely used in energy,chemical,electrical,mechanical and other fields.However,the thermal conductivity of polymers is generally low,and the thermal conductivity and thermal stability are poor,which limits the application range of polymers to a certain extent.Adding high thermal conductivity fillers to polymers can improve the thermal conductivity of the material,and the interface between the filler and the filler,the filler and the substrate is an important factor affecting the thermal conductivity of polymer composites,therefore,it is of great significance to understand and study the influence of the interface on heat transport in polymer-based nanocomposites.In this paper,boron nitride and graphene are used as fillers,and epoxy resin is used as the base material.Molecular dynamics simulation,theoretical derivation and numerical calculation are used to study the influence of the interface on heat transport.For the overlapped boron nitride nanosheets,molecular dynamics was used to simulate the influence of the interface overlap area and the interlayer spacing.It was found that as the interface overlap area increased,the interface thermal resistance of the overlapped boron nitride sheet decreased.As the spacing between the boron oxide layers increases,the interface thermal resistance is increasing.The type of filler was changed,and overlapped graphene sheets and overlapped graphene/boron nitride sheets were constructed and simulated.At the same time,compared with the interface thermal resistance of overlapping boron nitride sheets,it was found that the interface thermal resistance of overlapping boron nitride sheets was the largest,and the overlapped graphene,followed by overlapping graphene/boron nitride sheets,and the interface thermal resistance of overlapping graphene sheets is the smallest,respectively(1.94-3.75)×10^-9m²·K/W?(1.234-3.37)×10^-9m²·K/W?(0.74-1.127)×10^-9m²·K/WFor a composite material with epoxy resin as the base material,a boron nitride/epoxy resin composite material with 5 layers is constructed,and the thermal conductivity between boron nitride/epoxy resin is obtained,which is 0.224W/(m·K)-0.3017W/(m·K);changing the type of filler,simulating the working conditions when boron nitride and graphene are mixed into epoxy resin,it is found that the interface thermal resistance between graphene/epoxy resin is greater than the interface thermal resistance between boron nitride/epoxy resin.The thickness of the interface formed by boron nitride and epoxy resin is greater than the thickness of the interface between graphene and epoxy resin.When theoretical derivation and numerical methods are used for the macroscopic thermal conductivity of composite materials,the interface thermal resistance obtained by molecular dynamics simulation is substituted.The deduction and calculation results show that when the filler size reaches the micron level,the interface thermal resistance has little effect on the thermal conductivity of the composite material.In addition,the influence of the interface thermal resistance on the thermal conductivity of the composite material when the relative position of the filler changes is briefly analyzed.