“Thermal Stabilization Effect” of Al2O3 nano-dopants improves the high-temperature dielectric performance of polyimide

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.

The Synergistic Effects of the Micro and Nano Particles in Micro-nano Composites on Enhancing the Resistance to Electrical Tree Degradation

“…Figure 6b shows the trap level density distribution of the composites obtained by numerical calculation method 40 according to the thermally stimulated current (TSC) curves. The incorporation of nano particles decreases the trap level density of the composite, which is similar to the results in previous research 41 . Because the origin of depolarization current is the injection of electrons/holes, the less trap level density detected indicates the less injection of charges, which is caused by the interface introduced by the nano particles.…”

Polymer/molecular semiconductor all-organic composites for high-temperature dielectric energy storage

“…This is fundamentally different from the insulating nanostructures in the previous high-temperature polymer nanocomposites, which introduce trap sites mainly through modification of the polymer chain conformation and arrangement in the particle/matrix interface (the Φ e is usually below 1.0 eV) ( Fig. 1c) 14,20,21 . We hypothesize that the deep traps introduced by the molecular semiconductors would firmly immobilize the free electrons in the polymer even under high temperature and high electric field conditions if the molecular semiconductors are thermally stable and their concentrations are well below the percolation threshold.…”

Multilayer polyimide nanocomposite films synthesis process optimization impact on nanoparticles dispersion and their dielectric performance

“…where n is the total number of breakdown measurements and i is the iteration from 0 to the total number of breakdown strength data. The value of P can be obtained from Equation (3). It can be seen from Figure 11 that the breakdown strength improves by adding nanoparticles into PI matrix but in the case of single layer alumina mixed nanoparticles, we obtained the opposite result.…”

“…Polyimide (PI) films as an insulating material are used in such motors, which are commercially available in single or multicoated forms. [1][2][3] These low dielectric constant thin films are highly corona resistive, thermally stable, and have higher breakdown strength electrically and mechanically. 4,5 Such unique characteristics have made PI films to use in large industrial applications, such as aerospace, automotive, and electronics devices.…”