Abstract
Insulation performance of the dielectrics under extreme conditions always attracts widespread attention in electrical and electronic field. How to improve the high-temperature dielectric properties of insulation materials is one of the key issues in insulation system design of electrical devices. This paper studies the temperature-dependent corona resistance of polyimide (PI)/Al2O3 nanocomposite films under high-frequency square-wave pulse conditions. Extended corona resistant lifetime under high-temperature conditions is experimentally observed in the 2 wt% nanocomposite samples. The “thermal stabilization effect” is proposed to explain this phenomenon which attributes to a new kind of trap band caused by nanoparticles. This effect brings about superior space charge characteristics and corona resistance under high temperature with certain nano-doping concentration. The proposed theory is experimentally demonstrated by space charge analysis and thermally stimulated current (TSC) tests. This discovered effect is of profound significance on improving high-temperature dielectric properties of nanocomposites towards various applications.
Highlights
Polymer/nano-filler composites have attracted a great deal of interest for scientific researches and industrial applications in many fields including aerospace, biomedicine, structural materials, electronic and electrical engineering
Zha et al found that nano-TiO2 particles could improve the dielectric strength, lifetime, and space charge characteristics based on the dielectric properties tests of PI/TiO2 nanocomposites[19,20]
Pyromellitic dianhydride (PMDA) and 4,4′-Oxdianline (ODA) are chosen as the monomers to prepare Kapton (Method section), a kind of PI first developed by DuPont
Summary
Polymer/nano-filler composites have attracted a great deal of interest for scientific researches and industrial applications in many fields including aerospace, biomedicine, structural materials, electronic and electrical (or power) engineering. Based on the results of PEA and TSC tests, the underlying mechanism of this effect along with its nano-doping-concentration and temperature dependence is interpreted in reference to the “multi-core” model with an innovative temperature-dependent nanostructure of phase interface introduced. This improved model reveals a candidate theoretical foundation for refined nanodielectrics design with the optimal nano-doping concentration under high-temperature conditions of various electrical insulation applications. Further investigation about this effect is of great significance in characterizing and modeling the phase interface regions of polymer nanocomposites
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