Study Of Thermal Conductivity And Mechanism Of Graphene/Epoxy Composites

Graphene/epoxy composites were widely used in electronic packaging because of the excellent thermal conductivity.Nevertheless,the formation of thermal transfer pathways of graphene/epoxy composites could be severely weakened by the agglomerate of graphene and poor interface compatibility between graphene and matrix.Therefore,the graphene dispersion in epoxy matrix and interface compatibility between graphene and epoxy matrix are the key issues for the application of thermally conductive composites.In this paper,the enhanced thermal conductivity of composites was achieved by reduced graphene and synergistic effects of reduced graphene/inorganic fillers.The improved dispersibility of graphene in epoxy matrix was achieved by self-assembly hybrid particles between graphene and thermoplastic microparticles,and the interface compatibility and thermal conductivity of graphene/epoxy composites were simultaneously realized.1.Thermally reduced graphene oxide(TrGO-500,TrGO-700,TrGO-900)were prepared by heating treatment of GO at 500 ?,700? and 900?,respectively.Chemical reduced graphene(RGO-400?RGO-60)was obtained from grafting reaction between polyether amine(D230)and graphene oxide(GO).The structure and reduction degree of different reduced graphene were analyzed,and the effect of graphene on thermal conductivity of composites were studied.The reduction degree of thermally reduced graphene oxide was higher than those of reduced graphene.The thermal conductivity of composites was enhanced,which was attributed to the formation of covalent bonding,improving interface compatibility and decreasing thermal interface resistance between chemical reduced graphene and epoxy matrix.2.The thermal conductivity of composites were improved by synergistic enhancement of reduced graphene and functionalied boron nitride(TrGO-900/BN-G,RGO-60/BN-G).The synergistic effect of reduced graphene and BN-G was analyzed,and the enhanced thermal conductivity of TrGO-900/BN-G/EP and RGO-60/BN-G/EP composites was studied.The improved dispersibility of BN-G was achieved in epoxy matrix by functionalized boron nitride.Compared to RGO-60/BN-G,the thermal conductivity of TrGO-900/BN-G was significantly improved,which was attributed to the improvement of interfacial compatibility between TrGO-900 and matrix and formation of effective more thermal transfer pathways.3.A hybrid particle was fabricated via self-assembly of TrGO-900 and polyamide(PA)microparticles,and self-assembly mechanism of hybrid particles(TrGO-900-PA)was analyzed.The effect on interface compatibility,thermal conductivity and thermal transfer mechanism of hybrid particle was studied.The hybrid particle was prepared by electrostatic adsorption between the positive of TrGO-900 and negative of PA microparticles,and their absolute value reached the maximum(7%)at pH=7.The thermal conductivity of TrGO-900-PA/EP composites was improved with the incorporation of hybrid particle,which was attributed to the enhancement of interface compatibility between the graphene and matrix and the improved dispersibility of graphene in epoxy matrix.The thermal conduction mechanisms of framework PA microparticles and thermal conductivity medium TrGO-900 was illustrated in the schematic model.