Study On Preparation And Properties Of PI/Nano-Al₂O₃ Hybird Films

In this paper, poly(amic acid) was synthesized by step-polycondensation of 4,4'-oxydianiline(ODA) and pyromellitic dianhydride(PMDA)in the solution of N,N-dimethylacetamide(DMAc). Many series of polyimide/nano-Al₂O₃ hybrid films were prepared by the addition of the nano-Al₂O₃ which has been treated by coupling agent into the poly(amic acid) solution by ultrasonic wave through the ultrasonic-mechanical method and thermal imiditation.The micro-morphology of PI hybrid films and degree of order of polyimide molecular were studied by SEM and spectra of X-ray diffraction. Transmittivity of UV-Vis, thermal stability, mechanical properties and breakdown strength of PI hybrid films were tested. SEM analysis showed that the contents and crystallographic of nano-Al₂O₃ and the species and amount of silane coupling agents had much effect on the dispersion of nano-Al₂O₃ particles in the PI hybrid films. Spectra of X-ray diffraction and UV-Vis transmittance analysis showed that the contents and crystallographic of nano-Al₂O₃ and the species of silane coupling agents had much effect on the degree of order of polyimide molecular and transmittance of UV-Vis of PI hybrid films, but the content of silane coupling agent had less effect on them. TGA, mechanical and breakdown strength analysis showed thermal stability and breakdown strength of PI/nano-Al₂O₃ hybrid films were higher than pure PI film, but mechanical properties of PI/nano-Al₂O₃ hybrid films were lower than that of pure PI film. Thermal stability and tensile strength of PI hybrid films withγ-Al₂O₃ is higher thanα-Al₂O₃; in the PI/nano-Al₂O₃ hybrid films, the nano-Al₂O₃ was treated by four kinds of coupling agent, thermal stability and mechanical properties of PI hybrid films with KH550 were the best; breakdown strength of PI hybrid films with AE3012 was the highest; when silane coupling agent AE3012 is 4wt% of mass percent of inorganic particles during modifying treatment, thermal stability , mechanical properties and breakdown strength of PI hybrid films were the best.