Synthesis And Characterization Of Corona-Resistance Nanocluster-Trapped Polyimide

Polyimide (PI) had been widely used in electric industries because of their outstanding characteristics, such as excellent tensile strength and modulus, low thermal expansivity and dielectric constantε,good insulation capacity and good resistance to organic solvents.In the recent years, along with the rapid development of generator industry high frequency generator and high voltage generator had appeared. In this case, the demand of insulation materials in the generator had reached a new level. Not only mechanical strength, modulus and thermal stability but also the corona-resistance capacity had been an very important factor. Though the corona-resistance capacity of a pure PI is good. It's not far enough. Obviously, inorganic materials such as metal oxide have some excellent performance, but they have many unconquered problem in the practice. PI is also limited with regard to additional improvements in performance because of the limitation inherent in all organic materials. This suggests incorporating inorganic materials such as ceramics to provide enhancement.This article emphasized on the synthesis and characterization of the corona-resistance nanoclusters studded PI/SiO2 film. First we obtained the solution of polyamic acid (PAA) in N, N'-dimethylacetamide(DMAc) by the reaction of the materials of Pyromellitic anhydride(PDMA) and bis(4-aminophenyl)ether(ODA) in the solvent N,N'-dimethylacetamide (DMAc).Then we have successfully prepared silicahybrid films by the sol-gel reaction staring from tetrethoxysilane (TEOS) and Methyltriethoxysilane(MTEOS) in the solution of polyamic acid(PAA) whose solvent is N,N'-dimethylacetamide where the hydrolysis and polycondensation of TEOS and MTEOS as well as the connection with the polymer of polyamic acid appeared. Finally we obtained the films by heating step by step until 573K,the heating progress was last five hours. The film was characterized by Fourier Transform Infrared Spectroscope (FTIR), Scanning Electron Microscope (SEM), Atom Forth Microscope (AFM), X-ray Photoelectronic Spectrum (XPS), and corona-resistance tests. The results proved that the corona-resistance have general rule with the diffquantity of the ingredients. We also studied the relations between the conditions of reactions such as temperature of reaction, the ratio of original materials,the order of adding each material, the content of silica and polyamic acid, changing precursors of silica and the properties of the PI/SiO2 filmserentingredients and different.