| Polyimide is a kind of macromolecule insulating film material. Inorganicnanoparticles hybird polyimide has good dielectric properties, thermal properties andoptical properties, so it has good prospects of development in the field of integratedcircuit, electricity, transportation, aerospace, electrical insulation, health care and alot of other related fields. Alumina （Al2O3） has high resistivity, thermal conductivityand big forbidden band width, meanwhile, dielectric properties and ultravioletabsorption ability of Titanium dioxide （TiO2） is better. Studying the effects of thetypes of nanoparticles on the properties of composite films can provide a certainbasis for the development of nano dielectric substance.In this paper, several series of inorganic nanocomposite polyimide filmsincluding pure PI film, A（single layer films doped Al2O3）, AS（temary layer filmsdoped Al2O3）, T（single layer films doped TiO2） and TS（temary layer films dopedTiO2） are prepared by situ polymerization. The ultraviolet spectrum, SEM and XRDis used to characterize the chemical structure, morphological property and phasestructure of composite films, and the dielectric spectrometer, corona resistancetesting device and thermo-gravimetric apparatus is also used to test the electricalproperties and thermal properties of composite films. The results indicates that thenanoparticles in PI matrix has uniform distribution, while it composites well withpolymer matrix; With the increase of the content of nanoparticles, the dielectricpermittivity, dielectric loss and ac conductivity of composite films increases, and thedielectric permittivity, dielectric loss and ac conductivity of three-layer films arelower than that of single layer films. At the same time the dielectric performance ofPI/TiO2composite films are better than that of PI/Al2O3composite films; With theincrease of the content, the thermal decomposition temperature of polyimide filmsincreases, and thermal stability of the three-layer composite films is better than thatof single-layer film, and the thermal stability of PI/Al2O3composite films is better than that of PI/TiO2composite films; With the increase of content, the resistivity andcorona resistance lifetime of composite films are all increases first and thendecreases. It causes the phenomenon of reunion when the nanoparticles increase. Thenumber of the defects in PI matrix structure increases, and the superposition ofinterface layers forms the transport express way of the carrier. When a chargedparticle bombards the surface of films, there will be a lot of particles flowing into thechannel, which destroys the combination between inorganic nanoparticles andorganic polymer chains, in the end, the performance of films degrades. the insulationperformance of PI/Al2O3composite films is superior to that of PI/TiO2compositefilms. The resistivity of AS-25wt%is23.7×1016cm and its corona resistancelifetime reaches32h. Above all, the comprehensive performance of three-layercomposite films is better than that of single-layer composite films, thecomprehensive performance of films doped Al2O3nanoparticles is better than that ofthe films doped TiO2nanoparticles, and in the four series of composite films, thecomprehensive performance of AS-25wt%is the best. |
