Study On Dielectric Properties Of Polyaniline / Polyimide Composite Films

Due to its unique dielectric properties,novel nano-composite polymer based dielectric materials have important application value in the fields of high voltage insulation,thermal interface materials,sensing,wave absorption,energy storage,5G communication and so on.Through the composition and structure design of nanocomposite dielectrics,the regulation mechanism of physical parameters such as dielectric properties is revealed,which gives dielectric materials better properties.Polyimide(PI),as a dielectric material with excellent comprehensive properties,has become a popular matrix resin in the research field of nano-composite dielectric materials due to its good mechanical,thermal and dielectric properties.Polyaniline(PANI),as a kind of polymer material with unique properties,has adjustable electrical conductivity and chemical stability.It is a common design strategy to prepare polymerbased dielectric materials using nano-or micro-scale ceramics or carbon-based fillers,while the use of conductive polymers as nano-fillers to prepare polymer-based dielectric materials is relatively rare.Exploring the influence of PANI structure control,imidization temperature,secondary doping concentration,content and other factors on the dielectric properties of PANI/PI composite films provides data and theoretical support for the application of new dielectric materials in potential fields.In this paper,PI was selected as the matrix material.PANI with adjustable conductivity was selected as nano filler.PANI nanofibers were prepared by interfacial polymerization and doped with dodecylbenzenesulfonic acid(DBSA)to investigate the effects of acid doping on the morphology,electrical conductivity and thermal stability of PANI.PANI/PAA composite adhesive liquid was prepared by solution blending method,and the film was spread by flow-casting method.PANI/PI composite film was obtained by thermal imination.The influence of imination temperature,concentration of DBSA secondary doping PANI and content of PANI filler on the dielectric properties of PANI/PI composite film was investigated.The results show that PANI with nanofiber structure was synthesized by interfacial polymerization,and the nanofiber structure of PANI did not change with de doping and secondary doping.PANI has good dispersibility in the PI matrix.When the thermal imidization temperature of the PANI/PI composite film is 170°C,the composite film can not only guarantee the performance of the PANI filler,but also ensure the performance of the film in the later related tests.With the increase of doping concentration,the conductivity of PANI shows a trend of first rising and then falling.The dielectric constant of PANI/PI composite film has the same trend of change.When PANI is doped twice with 1.0 mol/L DBSA,the doping concentration makes the conductivity of PANI-DBSA have a maximum value of 2.852 S/cm.At 10 Hz,the dielectric constant of the PANI/PI composite film is 6.5,The dielectric loss is 0.02.The dielectric constant of PANI/PI composite films increases with the increase of PANI filler content.When the PANI filler content is 9 wt%,the dielectric constant of the composite film increases the most,and the filler content is the percolation threshold.When the PANI filler content is 15 wt%,at 10 Hz,the dielectric constant of the PANI/PI composite film is 8.8,and the dielectric loss is 0.044.