Fabrication And Performance Research Of Carbon-Based-Boron Nitride/Polymer Thermally Conductive Composites

Under the development trend of integration,miniaturization and high power of electronic components,the heat generated by the device during operation increases significantly,resulting in the overheating problem that seriously affects the safety and stability of electronic equipment.In order to eliminate the accumulated heat in electronic components and ensure the normal operation of the equipment,it is urgent to develop high-performance thermal management materials.Due to the advantages of low density,easy processing and high thermal conductivity,polymer-based thermally conductive composites have become the key to solve the heat dissipation problem of electronic devices.However,the construction of thermal conduction path and the regulation of interfacial thermal resistance in polymer-based thermal conductive composites have become the bottleneck restricting their development and application.In this thesis,based on the design of carbon-boron nitride composite filler structure,under the premise of effectively reducing the thermal resistance of filler interface,hot pressing and ice template were used to construct the oriented thermal conduction path in the composite material,so as to prepare high performance polymer-based thermally conductive composites.1.Design and construction of graphene nanoplanes(GNPs)-boron nitride nanotubes(BNNTs)/polyvinylidene fluoride(PVDF)thermally conductive composite material.In view of the problem of interface thermal resistance between graphene layers,BNNTs were grown in situ on the surface of graphene nanoplanes which prepared by the exfoliation method(E-G)to obtain a composite thermally conductive filler structure of E-G and BNNTs(E-G–BNNT),and the PVDF-based thermally conductive composite material with the orientation arrangement of E-G–BNNT(E-G–BNNT/PVDF)was formed by the hot pressing method.The BNNTs structure bridged between the E-G layers effectively connects layers via C-N covalent bonds,which contributed to the reduction of the interface thermal resistance between E-G layers.Due to the continuous heat transfer pathway formed in the vertical direction of E-G–BNNT/PVDF,its through-plane thermal conductivity was greatly improved,reaching 3.12 W/(m·K)at a loading of 15 wt%.Such excellent heat conduction performance of E-G–BNNT/PVDF makes it show certain application potential for thermal management.2.Design and construction of boron nitride nanosheets(BNNSs)-carbon nanotubes(CNTs)/epoxy resin(EP)thermally conductive composite materials.Considering the integrity and long-range order of the heat transfer pathway can further improve the thermal conductivity of the composite material,this work was from the perspective of reducing the interface thermal resistance between the fillers via in situ connection.CNTs were grown in situ between the BNNSs skeletons prepared by the ice template method,and the covalent bonds were used to make the oriented BNNSs effectively connected.While reducing the thermal resistance of the interface between BNNSs,a through heat transfer pathway was constructed in the meantime.The EP-based thermally conductive composite material(o-BN/ZC/EP)was prepared by perfusion method.The establishment of an effective heat transfer pathway provided a guarantee for heat transfer.The thermal conductivity value can reach 3.21 W/(m·K)when the filler loading is 9.86 vol%.This work provided new design and preparation ideas for the development of high-performance thermal management materials.