Preparation And The Properties Investigation Of Nano-carbon And Polyimide Compostie Films

In the past few years, because of the tending of electronic miniaturization,the demand of high dielectric constant material has been increased fast. Thetraditional high dielectric constant material becomes a bottleneck restrictingthe development of electronic devices. Recently, polymeric dielectriccomposite material has received a lot of attention for its unique advantages.However, Since the majority of polymer material have a small dielectricconstant, usually needed adding high dielectric or conductive filler to achievea high dielectric constant. Especially the polymer/carbon nano-compositematerial has been gained intensively concern in the novel electronic materials.This paper fabricates a series of polyimide/carbon nano-compositematerials using polyimide as the the polymer matrix and two-dimensionalgraphene, nano graphite sheet, one-dimensional carbon nanotube andzero-dimensional carbon nanosphere as fillers respectively. And the influenceof conductive fillers’ type, surface structure, contents and polarity to thethermal stability, mechanical properties and electric properties of thecomposite materials has been systematically researched. The main results areas follows. Elemental analysis (EA), X-ray Diffraction (XRD), Raman andTransmission Electron Microscope (TEM) were employed to characterize thecomponent, structure and surface morphology of the above three kinds ofcarbon materials. Through the ultrasonic dispersion and in-situ synthesismethod, a series of polyimide/carbon nano-composite films in related to theabove carbon materials have been prepared, and the dispersibility of the fillersin the matrix was investigated. Thermal gravimetric analysis (TGA), dynamicmechanical thermal analysis (DMA), universal testing machine test andprecision impedance analyzer instrument were used to analyse the influence ofthree different type of carbon materials fillers to the thermal stability,mechanical properties and electrical properties of the nano-composite films.The results show that the doping of all the above three fillers can improve thedielectric permittivity of polyimide film, and the percolation threshold hasbeen calculated according to the percolation threshold model equation. All thefillers have a positive effect on the mechanical properties and thermalproperties of the nano-composite films, while, the tensile strength can reach ashigh as158Mpa which is38%higher than the pure polyimide films. Besides,a conductive polyimide/carbon nano-composite material has been synthesizedwhen the P-NGPs are acted as fillers. The conductivity of this nano-compositematerial is3.64*10-2S/m when the filler content is10%. Comparing the threedimensions of the filler in improving the dielectric properties of the PI matrix,the results show that as the doping amount is same, graphene with high surface area improved the dielectric properties of polymer most significantly.