Fabrication And Characterization Of Thermally Conductivity Boron Nitride-filled Polymer Composite

As the rapid development of modern information and aviation science,the continuing miniaturization of size and increased power densities in modem electronics result in accumulated heat which inevitably cause thermal failure.Efficient thermal dissipation has become a stringent necessity in miniaturized electronic devices for longer lifetime and higher speed.Thermally conductive materials are believed to be the best choice to help address the heat-removal issue.In this study,our interest to improve the thermal conductivity of polymer is foused on the selective addition of high thermal conductive fillers,such boron nitride?BN?,boron nitride nanosheet porous sphere?BNNS-Ag sphere?and boron nitride nanosheet-Ag porous sphere?BNNS-Ag sphere?.Firstly,PC composites containing oriented BN plates were prepared by hot-pressing method.XRD and SEM analysis confirmed that BN sheets are oriented parallel to the composite surface inside linear assemblies of BN sheets with high anisotropy.The thermal conductivity of horizontally oriented BN/PC?HoBN/PC?composite at 18.7 vol%loading reaches 3.09 Wm^-1K^-1and increases by nearly 1371%over neat PC.Meanwhile,the thermal infrared imaging characterization show that HoBN/PC composite material has good heat dissipation effect.Furthermore,the storage modulus of HoBN/PC composite at 18.5 vol%BN loading reaches 4.26x 10⁹ Pa as the orientation of BN plates can strengthen the deformation resistance of HoBN/PC composites.The increment in storage modulus is 115.1%for HoBN/PC composite at 18.7 vol%BN loading when compared to that of neat PC.The thermal composite material,which can be fabricated by a reasonably low-cost method,may provide a broader outlook for its further use in electrons.In the longer term,this facile strategy supply more development for the advanced thermal-management materials.Secondly,sonication-assisted exfoliation was applied to prepare BNNS.BNNS-Ag hybrids were then fabricated by depositing silver nanoparticles on BNNSs via the reduction of Ag+ salt.The result of surface modification was characterized by scanning electron microscopy?SEM?,transmission electron microscope?TEM?,and X-ray power diffraction.The BNNS-Ag hybrids were then ice-templated assembled into spongy millispheres with tunable microstructures.The results showed that the specific surface area of BNNS microspheres reached 227.92 m²/g and the porosity was 89.2531%.The thermal conduction performance,thermal stability and electric properties of composites were investigated.At the sphere content of 2.7 vol%,the through-plane thermal conductivity of BNNS sphere/epoxy composite reaches 0.57 Wm^-1K^-1,while the value for BNNS-Ag sphere/epoxy composite reaches 0.64 Wm^-1K^-1;indicating the corresponding enhancements of 12.3%and 276.5%towards BNNS sphere/epoxy composite and pure epoxy,respectively.The BNNS sphere/epoxy composite exhibits a high volume resistivity(1.57×10¹⁴?cm),which is far higher than the standard of insulators(1.0×10¹⁰? cm).The addition of silver particles still keep the composite at the same order of magnitude(1.23×10¹⁴?cm),indicating that the addition of silver particles has little effect on the electrical insulation properties of the composites.The obtained composites exhibited strong potential for thermal management applications for a variety of technological needs,particularly electronic packaging.