Preparation And Performance Of Nano Al₂O₃ Modified Polyesterimide

Polyesterimide has excellent electrical properties,mechanical properties,radiation resistance and high temperature resistance.But its corona resistance life is low,which limits its application in high voltage motor and variable frequency motor system.The inorganic materials are doped into the organic matrix,which can synthesize the advantages of organic and inorganic materials,to obtain more excellent properties.In this paper,inorganic nano Al₂O₃ was doped into polyesterimide resin,and nano modified polyesterimide composite material was prepared and tested.The method to improve the corona resistant life of polyesterimide resin was studied.This paper uses prepared nano Al₂O₃ modified on the surface of nano Al₂O₃ with methyltriethoxysilane,prepared two kinds of composites: PEI/Al₂O₃ system and PEI/M-Al₂O₃ system.The electrical properties of the two materials were tested by the electric current test device,the corona resistance test device,the dielectric strength test device and the dielectric spectrometer: The surface morphology and microstructure were characterized vis SEM,TEM,FTIR;thermogravimetric analyzer,gel tester and viscometer on material process performance was tested,and the test results are analyzed.The results of SEM and TEM showed that nanoparticles were dispersed in two systems.Nano Al₂O₃ particles modified by methyltriethoxysilane could make nanoparticles distribute more evenly in composite materials and further improve their properties.The corona resistant life of PEI/Al₂O₃ composites is 5.15 times higher than the pure PEI,the corona resistant life of PEI/M-Al₂O₃ composites is 9.8 times higher than the pure resin;conduction current test results show that the electrical degradation threshold of materials increased with increasing amount of nano Al₂O₃,and with the increase of methyltriethoxysilane dosage increased,compared to the nano Al₂O₃ effect of methyltriethoxysilane modified Al₂O₃ nanoparticles on the material carrier accumulation rate is greater;dielectric spectra test results show that the dielectric constant of PEI/Al₂O₃ composites increased with the increase of nano Al₂O₃ doping and methyltriethoxysilane was increased,the dielectric loss increased with the increase of nano Al₂O₃ and methyltriethoxysilane dosage showed a slightly downward trend,in the low frequency region,effects of methyltriethoxysilane on the composites greatly;the dielectric strength of the composites decreased sharply compared with that of the pure resin.After the modification of the nanoparticles,the dielectric strength of the PEI/M-Al₂O₃ composites increased first and then decreased with the increase of the amount of methyltriethoxysilane.