Polyester-Imide Solventless Impregnating Varnish Modified By Activited Nano-Alumina Sol

Organic/inorganic hybrid materials have obtained more and more attentions in the fields of mechanics, thermodynamics, optics, electromagnetics, and biology etc, for their special properties. Polyesterimide, as a typical kind of non-solvent impregnating resin, has been widely used in the electronic and electric industry because of its outstanding performances, such as highly heat-resistance, good radiation-resistance, easily solidified in low temperature, steadily reserved, excellent combination properties. However, it has inferior corona-resistance property, which limits its application in the fields of variable frequency adjusting speed. In order to obtain excellent electric properties especially on the corona resistance, the nano-sized alumina/polyesterimide composites have been systhesized and characterized.In this paper, nano-alumina were prepared with aluminium isopropoxide. Activated Nano-Alumina Sol modified Polyester-imide solventless impregnating varnish.Effects of dielectric property, nanostructure distribution, thermal Stability was studied.It was showed that Activated Nano-Alumina Sol modified Polyester-imide has well-proportioned nano structrue by the SEM, better corona-resistant lifespan. The corona-resistant lifespan of polyesterimide film with 15wt% amount of alumina (counting as Al2O3) is 8 times longer than that of pure film. The relative dielectric constantεr of alumina powder hybrid polyesterimide film has been progressed. The relative dielectric constantεr of composite film is higher than pure film and alumina powder hybrid polyesterimide film. The dielectric loss tanδof hybrid polyesterimide film has been reduced under the 10wt% amount of alumina but been improved in the 15wt% amount of alumina. There is deference rheology effect between the alumina hybrid polyesterimide film and the pure film.The Activated Nano-Alumina Sol modified Polyester-imide film has better rheology than the alumina powder hybrid polyesterimide film.Thermal ability of the alumina hybrid polyesterimide has been improved .