The Role of Interfaces in Polyethylene/Metal‐Oxide Nanocomposites for Ultrahigh‐Voltage Insulating Materials

Abstract

Recent progress in the development of polyethylene/metal-oxide nanocomposites for extruded high-voltage direct-current (HVDC) cables with ultrahigh electric insulation properties is presented. This is a promising technology with the potential of raising the upper voltage limit in today's underground/submarine cables, based on pristine polyethylene, to levels where the loss of energy during electric power transmission becomes low enough to ensure intercontinental electric power transmission. The development of HVDC insulating materials together with the impact of the interface between the particles and the polymer on the nanocomposites electric properties are shown. Important parameters from the atomic to the microlevel, such as interfacial chemistry, interfacial area, and degree of particle dispersion/aggregation, are discussed. This work is placed in perspective with important work by others, and suggested mechanisms for improved insulation using nanoparticles, such as increased charge trap density, adsorption of impurities/ions, and induced particle dipole moments are considered. The effects of the nanoparticles and of their interfacial structures on the mechanical properties and the implications of cavitation on the electric properties are also discussed. Although the main interest in improving the properties of insulating polymers has been on the use of nanoparticles, leading to nanodielectrics, it is pointed out here that larger microscopic hierarchical metal-oxide particles with high surface porosity also impart good insulation properties. The impact of the type of particle and its inherent properties (purity and conductivity) on the nanocomposite dielectric and insulating properties are also discussed based on data obtained by a newly developed technique to directly observe the charge distribution on a nanometer scale in the nanocomposite.

Electrical Properties of Polyethylene/Polypropylene Compounds for High-Voltage Insulation

“…The onset temperature of pure PP was 123 • C, and for the samples containing LDPE was 124 • C, 125 • C, and 125.3 • C, thus slightly higher than those of pure PP. In the case of HDPE/PP, the crystallization onset temperature was between 118 • C and 119 • C, which confirms that HDPE has a greater effect on PP crystallization than LDPE [26,31,32]. Table 3.…”

“…In polymer insulation materials, the permeation of charge carriers (ionic or polar molecules), holes, and excess electrons depends on their crystallinity. Mixing two different polymers with different ratios results in changes in the charge mobility behavior, which has a significant effect on the material conductivity [26]. At room temperature, polymers consist of both crystalline and amorphous phases.…”

Influence of Conductive and Semi-Conductive Nanoparticles on the Dielectric Response of Natural Ester-Based Nanofluid Insulation

“…The question is why an identical phenomenon is also reported for semi-conductive and dielectric-based nanofluids [16]. It was believed that the enhancement of dielectric strength in nanofluids not only depends on the intrinsic properties and interface regions formed between particles, as in solid phases [17][18][19]. However, it strongly depends on the potential mobility of charged particles in nanofluid due to electric field orientation.…”

A Parameterization Approach for the Dielectric Response Model of Oil Paper Insulation Using FDS Measurements

“…With the development of high-voltage direct current (HVDC) transmission, polymeric insulation material like polyethylene has been increasingly adopted in HVDC appliances [39], e.g., HVDC power cables. However, in the current stage, we limit the discussion here only to traditional OIP insulation, as OIP structures dominate insulation in most AC equipment at present.…”