Research On The Thermal Conductivity Of Graphene Polymer Composites

In the field of electronic manufacturing,with the decreasing of the volume of electronic components and the increasing power consumption,there is a higher demand for thermal conductivity of materials.Polymer materials have the advantages of light weight,low price,easy processing and design.However,polymer materials generally have low thermal conductivity,which limits their further application in the fields of electronic components,LED lamps and automotive parts.In view of this characteristic,researchers try to use high thermal conductivity fillers to fill polymers to improve their thermal conductivity.Among the common high thermal conductivity fillers,graphene has unique thermal properties,which can significantly improve the thermal conductivity of polymers in low filling rates.However,the effect of graphene on the thermal conductivity of different polymers and its influencing factors remain to be further studied.Therefore,in this paper,graphene was used as the filler and polyamide 6(PA6),polypropylene(PP),and high density polyethylene(HDPE)were used as the matrix materials with wide application,high yield and urgent improvement in thermal conductivity.The effects of different graphene mass fractions on the thermal conductivity of graphene/polyamide6(GE/PA6),graphene /polypropylene(GE/PP),graphene/high density polyethylene(GE/HDPE)composites and their internal mechanisms were studied by melt blending experimental method and molecular dynamics simulation.The main research contents and results are as follows:Firstly,in this paper,the filler graphene in composites was simulated by molecular dynamics simulation,and the key factors affecting the thermal conductivity of graphene were studied.The simulation results show that the increase of the feature size will improve the thermal conductivity of graphene.The results obtained by different potential functions are significantly different.The thermal conductivity of graphene increases with the increasing of ambient temperature.Subsequently,GE/PA6,GE/PP and GE/HDPE composite models with different graphene mass fractions were established by molecular dynamics simulation.Thermal conductivity,interfacial thermal conductivity,interaction energy and radial distribution function of the composites were analyzed and discussed.The simulation results show that the filling of graphene effectively improves the thermal conductivity of the three polymers,and the enhancement effect is GE/PA6>GE/PP>GE/HDPE.The interaction between graphene and polymer molecules affects the thermal conductivity at the interface of the composites.The interfacial thermal conductivity and interaction energy of the three composites were: GE/PA6>GE/PP>GE/HDPE.With the increasing of the mass fraction of graphene,the distance between C atoms in graphene increases,and the C atoms gradually disperse uniformly,especially in GE/PA6 composites.Finally,GE/PA6,GE/PP and GE/HDPE composites with different graphene mass fractions which were the same as those of the simulation calculations were prepared by melt blending method.The micro-morphology and thermal conductivity of the three composites were measured.The results show that the simulation results of the thermal conductivity of GE/PA6,GE/PP and GE/HDPE composites are in the same trend as the experimental results.By comparing with the pure polymers,when the graphene mass fraction is 10%,the thermal conductivity of GE/PA6,GE/PP and GE/HDPE composites increased by 308%,209% and 82%,respectively.The bonding effects of graphene with PA6,PP and HDPE are different after filling graphene,and the three composites have different layer structure.