Study On Preparation And Dielectric Property Of Ag-graphene/PVDF Composites

High dielectric polymer matrix composite materials have been widely used in thefield of the electron or electricity engineering and technology. Because of the dielectricand mechanical properties of ceramic powder/polymer matrix composite materials isrestricted, the using range of that is limited, and ceramic powder/polymer matrixcomposite materials can not meet the need of the modern technology. Hence in order toimprove the dielectric and mechanical properties, the conductive fillers/polymer matrixcomposite materials are designed, the dielectric properties of the polymer is enhancedby the percolation of conductive fillers in the polymer matrix.In this study, firstly, graphite oxide was fabricated by Hummers method, andgraphene oxide was obtained after graphite oxide was treated under the ultrasonictreatment. And then Ag-graphene was fabricated under the reduction of NaBH4.Ag-graphene/PVDF composite materials have been prepared by using a melt blendingand hot-molding technique. The structure and morphology of Ag-graphene/PVDFcomposites materials prepared under different conditions were characterized by infraredspectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM)and Raman. The dielectric properties of Ag-graphene/PVDF composite materials wereinvestigated. The specific research contents are as follows:(1) There are a lot of polarity functional groups on the graphene oxide, eg.–OH、–COOH、C=O etc. The amount of the polarity functional groups on the graphene isdecreased and graphene conglomerates easily. Increasing the content of Ag in theAg-graphene composites materials, the amount of the polarity functional groups on thesurface of graphene is decreased, in the same time the intensity of Raman spectrum isincreased.(2) It can be found that the interlamellar spacing of graphene oxide is obviouslybigger than that of graphite through XRD. The value of interlamellar spacing ofgraphene is between that of graphite oxide and graphite. In study of Raman, it can befound that the degree of graphitization of graphite was decreased after graphite wasoxided.(3) The size of Ag particles is smaller than that of pure Ag in the Ag-graphene/PVDF composite materials. The Ag particles disperse uniformly on thesurface of graphene. Increasing the amount of Ag particles, the size of Ag enhances andthe conglomeration of Ag particles enhances more and more serious. The Ag-graphenedisperses uniformly in the PVDF matrix. Increasing the mass fraction of Ag-graphene,the Ag-graphene becomes conglomeration in the Ag-graphene/PVDF compositematerials.(4) Variation trend of the dielectric constant and dielectric loss ofAg-graphene/PVDF composite materials is similar, increasing of mass contents ofAg-graphene at103Hz. The the dielectric constant and dielectric loss ofAg-graphene/PVDF composite materials is maximum under the value of the percolationthreshold of Ag-graphene that is equal9wt%. The dielectric constant and dielectricloss of Ag-graphene/PVDF composite materials is710.65and8.93respectively.(5) Increasing frequency, the dielectric constant and loss of Ag-graphene/PVDFcomposites materials with different mass contents of Ag-graphene decreased. Thedecreasing margin of the dielectric constant and loss of Ag-graphene/PVDF compositesmaterials is the biggest under the value of the percolation threshold of Ag-graphene.