Researches On The Effect Mechanism Of Interface Thermal Resistance On The Thermal Conductivity Of Filled Composites

Filled thermal conductivity polymer composites are made of polymers and high thermal conductivity fillers,which have broad application prospects in lots of fields.Interfacial thermal resistance is one of the key influencing factors on the thermal conductivity of composite.Interfacial thermal resistance is frequently used to characterize the heat transfer state at the interface of materials,which has an important influence in the field of electronic packaging.In this paper,the formation mechanism of interfacial thermal resistance is analyzed first of all.Followed by the combining method of numerical calculation and theory was carried out to focus on the influence of interfacial thermal resistance on composites filled with core-shell,large-small spherical and different size of core-shell spherical fillers.Meanwhile,there are some other elements effecting the thermal conductivity of filled composites are investigated,which included filler contact,thermal conductivity and volume fraction.In addition,the influence of the interface thermal resistance corresponding to different shapes of fillers(ellipsoid shape,quadrangular prism shape,anagonal quad prism shape,square shape,T shape,conical shape,spherical shape,?shape)on the thermal conductivity of filled composites is also explored.The main research results are as follows.1.Composites filled with large and small spherical fillers:When the sum of the interface thermal resistance of the large ball and the small ball fillers is constant and the ratio of the interface thermal resistance of the two fillers is in the range of 10^-2-10,the thermal conductivity coefficient of the composite material is related to the competitive effect of the interface thermal resistance of the two fillers.When the interface thermal resistance of the large ball and the small ball fillers is constant and the thermal conductivity ratio greater than the critical value of 98,changing of the thermal conductivity ratio of the filler has large effect on the thermal conductivity of the composite material.2.Composites filled with core-shell filler:when the thermal conductivity of filler and the volume of the single filler are constant,the larger the volume ratio of the core to the shell,the greater the resistance of the interface to the heat flow.At the condition of the interfacial thermal resistance is larger(larger than 10 s³Kkg^-1),the interfacial thermal resistance has a greater influence on the thermal conductivity of the composites than the core-shell volume ratio and core-shell thermal conductivity ratio.The thermal conductivity of the fillers with different filling sizes is better than that of the same filling sizes.3.The thermal conductivity of the filled contact type is about 1.15 times higher than that of the isolated filled composite material.The contact type is easier to form effective structures and more effective heat conduction pathways than the isolated type,so the heat more easily transfers in the composite material and the thermal conductivity of the composite material is better.4.When filling the fillers of different shapes,the sensitivity of the fillers of different shapes to the interface thermal resistance is different.When the interfacial thermal resistance of the filler is smaller(less than 10 s³Kkg^-1),the composite materials are filled with eight different fillers respectively.Their thermal conductivity is as follows:ellipsoid shape>quadrangular prism shape>anagonal quad prism shape>T-shape>?shape>square shape>conical shape>spherical shape.When the interface thermal resistance of the filler is larger(more than 75 s³Kkg^-1),the thermal conductivity of the composite materials is in order:ellipsoid shape>quadrangular prism shape>anagonal quad prism shape>square shape>T shape>conical shape>spherical shape>?shape.The composites filled with ellipsoid fillers have longer thermal conduction path and better thermal conductivity.The higher the filler content,the easier it is to form a thermal conduction path and the better the thermal conductivity of the composite materials.