Investigation of temperature effects on voltage endurance for polyimide/Al₂O₃nanodielectrics

Abstract

In order to investigate the effects of inorganic nanofillers on the electrical properties of polyimide (PI), PI/Al 2 O 3 nanocomposites films were prepared via the in-situ polymerization. The hybrids films were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The dielectric behaviors of pure PI and PI/Al 2 O 3 samples were studied as a function of the measured frequencies and temperatures. Meanwhile, the breakdown strength of pure PI and PI/Al 2 O 3 samples measured at 25 and 230 ℃ was analyzed. The corona-resistant lifetime of samples under bipolar continuous square impulse voltage (BCSIV) was performed. With the wt% content of Al 2 O 3 nanoparticles increasing, the real (ε') and imaginary (ε") of relative permittivity present an increasing tendency, while electrical breakdown strength declines obviously. The Al 2 O 3 nanofillers improved the corona-resistant property of PI and the corona-resistant lifetime of PI/Al 2 O 3 sample with 25 wt% (weight percent) of nano-Al 2 O 3 particles is over 23 times longer than that of the pure PI film. Besides, the temperature is an important factor which would significantly influence the electrical properties of pure PI and PI/Al 2 O 3 samples. The elevated temperature would reduce the breakdown voltage and corona-resistant property.

Effects of surface fluorination on dielectric properties and surface charge behavior of water absorbed polyimide film

“…DUE to the excellent mechanical and electrical properties, PI film is widely used as insulation material in electrical and mechanical equipment, such as the insulation between the coil in wind generator and traction motor [1][2][3][4]. These kinds of equipment always work in adverse circumstances which will cause the exposure of PI to contaminated and moist conditions.…”

Failure Mechanism and Property Modification of Insulation Material Used in Inverter-Fed Motors

“…As shown in Figure 5 [22], the lifetime increases with the increasing nano-Al 2 O 3 content. For the PI/Al 2 O 3 nanocomposites with 25 wt.% content of nano-Al 2 O 3 , the lifetime is around 136 h, which is about 23 times longer than that of pure PI film, at the temperature of 25°C.…”

Synthesis Process Optimization of Polyimide Nanocomposite Multilayer Films, Their Dielectric Properties, and Modeling

“…The relative permittivity is composed of two parts: the real part denoted as ε′ and the imaginary part indicated as ε″. The ratio of these two values is defined as the dissipation factor and given as follows: Typically, PI films have dissipation loss in between 0.001 and 0.02 [10]. The low tan δ value indicates that PI loses less electrical energy.…”

“…The breakdown strength may vary by varying the temperature, moisture, and defects inside the material. The PI films that we synthesized have breakdown strength between 150 and 260 kV/mm [9,10]. Due to its high electrical breakdown strength and mechanically tough properties, PI as an insulation can be useful to utilize in a high voltage industry applications, where electrical instruments can produce strong electrical field and leakage current to damage the insulation.…”