Experimental And Simulation Study On Thermal/Electrical Transport Properties Of Polymer Nanocomposites

Polymer-based nanocomposites have a wide application prospect in many fields such as microelectronic devices,flexible thermoelectric devices.The study of electrical and thermal transport properties of polymer nanocomposites and the regulation of their macroscopic thermal/electric transport properties is of great guiding significance for the development of new and efficient thermoelectric devices and high-performance thermal interface materials.In this paper,numerical simulation methods were used to study the electrical and thermal transport properties of metal nanowire-polymer composites,and combined with the interface electron-phonon coupling,an effective strategy to promote the thermoelectric properties of the composites with electron percolation thermal insulator structure was analyzed.The simulation conclusion proposes a construction idea of a hybrid transport network using silver nanowires as thermally conductive silver bridges.The experimental preparation and thermal/electrical performance characterization of hybrid thermal interface composite were carried out,and the macro-control strategy of its performance was analyzed.In the simulation study,a nanowire composite structure model was established,and the electrical conductivity and thermal conductivity under different concentrations and nanowire aspect ratios were calculated by using Kirchhoff’s voltage law,a parallel model based on effective medium theory and Wiedemann-Franz law.When the conductivity reaches 1.06×106^S/m,it is found that the thermal conductivity increases from 0.2 Wm^-1K^-1 to 12.81 Wm^-1K^-1,confirming the simultaneous improvement of thermoelectric transport performance.Secondly,the effective thermal conductivity of nanowires with electron-phonon coupling at composite interface is analyzed.It is found that the thermal conductivity of the electron-phonon coupling is significantly reduced at a smaller diameter,while its electrical conductivity is not affected.Finally,the conductivity and thermal conductivity of 20 different sizes of nanowires at different concentrations were calculated and the size and concentration of nanowires were optimized according to the standard of high relative thermoelectric figure of meritIn the study,it was found that the penetration network construction idea of conductive silver bridge and the introduction of third-phase dielectric filler promoted the great improvement of the thermal conductivity of the composites.In the research,it was found that a cross-linked structure with a mass fraction of 60wt%graphene nanosheets/boron nitride nanosheets of 1:1 was used as the main body of the thermally conductive network,and 5wt%of silver nanowires was used as a hybrid transport network of thermally conductive silver bridges,and the thermal conductivity increases by 16 times from 0.19 Wm^-1K^-1 to 3.15 Wm^-1K^-1.Based on the ratio of 1:1,the composite materials with two 2d fillers’radio of 1:2,1:3 and 1:4 were prepared respectively.It was found at the ratio of 1:3,the thermal conductivity of the composites was increased by 23 times,from 0.19 Wm^-1K^-1 to 4.43 Wm^-1K^-1,and the volume resistivity was increased by 8 orders of magnitude compared with the pure graphene composites.The construction idea of an efficient heat transport network of thermal interface composite suitable for high insulating environment requirements is verified.