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The Preparation And Thermal Conductivity Of Nano Boron Nitride/Polymer Composites

Posted on:2020-06-19Degree:MasterType:Thesis
Country:ChinaCandidate:C J FuFull Text:PDF
GTID:2381330578453859Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
With the rapid development of integrate circuit industry,the development of modern electronics towards miniaturization,high-degree integration and multi-functionalization to fit the people'requirement for functionalized and convenient modern electronics.However,heat dissipation issue caused by modern electronic has been received attention.High conductivity polymer composites can be used to solve this issue.Many study of high conductivity polymer composites has been published,however,those composites can not fit the heat disspation's requirement of modern.In this study,high thermally condutive polymer composites were fabricated by choosing hexagonal boron nitride?BN?as thermally conductive fillers,and epoxy?EP?and nanofibrillated cellulose?CNF?as matrixes.The results are listed below:?1?Ag-BNNT hybrids were prepared through introducing Ag onto the surface of BNNT by the liquid deposition process.The Ag-BNNT/CNF composites were then prepared by the vacuum-assisted self-assembly process.The highest thermal conductivity reaches 20.9 Wm-1K-1 for composites with 25 wt%Ag-BNNT,which is approximately 2 times higher than that of composites with 25 wt%BNNT.On the basis of the EMT and Foygel model,we attribute the improved thermal conductivity to that introducing Ag onto the surface of BNNT can reduce the interfacial thermal resistance between adjacent BNNTs.?2?A 3D aerogel consisting of BNNS and AgNW hybrids fillers was fabricated by ice-templated assembly strategy and welding AgNW through low-temperature sinter process.The 3D BNNS-AgNW/EP composites were then prepared through infiltration technology.A highest out-of-plane thermal conductivity value of 1.10 Wm-1K-1 has been obtained,which is about 1.5 times and 2 times as high as that of unsintered BNNS-AgNW/EP composites and BNNS/EP composites,respectively.We attribute the improved thermal conductivity to that utilizing AgNW and welding AgNW through low-temperature sinter process can enhance thermal conductivity by enhancing the total contact area per volume between fillers.?3?The Ag-BNNS hybrids were prepared through introducing Ag onto the surface of BNNS by the liquid deposition process.We prepared a 3D aerogel consisting of Ag-BNNS and AgNW hybrids fillers by ice-templated assembly strategy and welding silver nanoparticles with AgNW through low-temperature sinter process.The 3D Ag-BNNS/AgNW/EP resin composites were prepared through infiltration technology.A highest out-of-plane thermal conductivity of 0.804 Wm-1K-1 has been achieved for the sintered Ag-BNNS/AgNW/EP composites,which is 1.5 times as high as that of the unsintered Ag-BNNS/AgNW/EP and 2 times as high as that of BNNS/EP at the same BNNS contents.On the basis of the Foygel model,we attribute the improved thermal conductivity to that introducing Ag onto the surface of BNNS and welding silver nanoparticles with AgNW through low-temperature sinter process can reduce the interfacial thermal resistance between BNNS and AgNW.In a word,we putted forward two quotable methods,which can be used to design and preparation of highly thermal conductivity polymer composites in the future,as follows:1)Builting“bridges”between fillers with silver nanoparticles can reduce the interfacial thermal resistance and improve the thermal conductivity of composites.2)We can prove the thermal conductivity of composites by feat of synergistic effect of hrides fillers,low melting effect of nano silver and ice-templated assembly strategy.
Keywords/Search Tags:boron nitride, nano silver, polymer composites, thermal conductivity, interfacial thermal resistance
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