Numerical analysis of space charge accumulation and conduction properties in LDPE nanodielectrics

Min, Daomin; Wang, Weiwang; Li, Shengtao

doi:10.1109/tdei.2015.7116341

Cited by 76 publications

(51 citation statements)

References 25 publications

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“…This qualitative analysis has much in common with the numerical simulation of space charge accumulation and conduction in nanocomposites described by Min et al [44], who highlight the importance of charge trapping in affecting both charge injection into nanodielectrics and subsequent charge transport dynamics in the bulk. Indeed, Figure 3 in [44], which presents the time dependent external current densities calculated for nanodielectrics containing different trap densities, shows, for some systems, a relatively rapid initial decrease in current density (up to about 100 s), followed by a regime in which the rate of decrease of current density is reduced (10 2 -10 4 s), after which, the current density increases.…”

Section: Discussionmentioning

confidence: 54%

“…Although more explicit ideas have been proposed based upon the formation of structurally distinct interphase zones [6], these should be considered as working hypotheses. Nevertheless, the influence of such factors on charge transport dynamics in nanodielectrics has been discussed by Min et al [44], who suggested the following: the presence of nanoparticles affects trapping energies and thereby the carrier mobility in the bulk; the conductivity of the interaction zone differs from that of the unaffected polymer; in nanodielectrics, the existence of trapping centres captures injected charges near the electrodes, thereby, affecting subsequent charge injection processes; the proposed interaction zones affects the electrode contact potential barrier.…”

Section: Introductionmentioning

confidence: 99%

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Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Lau

Vaughan

Chen

et al. 2016

J. Phys. D: Appl. Phys.

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The topic of nanodielectrics continues to receive significant attention from today's dielectrics community, due to the property enhancements that can stem from the unique interfacial features within such material systems. Nevertheless, understanding of the interfacial phenomena that occur in nanodielectrics and which determine their electrical behaviour is challenging. In this paper, we report on an investigation into the absorption current behaviour of two nanocomposite systems, one containing an untreated nanosilica and the other containing the same nanofiller chemically modified using trimethoxy(propyl)silane.The results indicate that the absorption current behaviour of all the nanocomposites is very different from that of the reference, unfilled polymer; while the current flowing through the unfilled polyethylene decreased monotonically with time in a conventional manner, all nanocomposites revealed an initial decrease followed by a period in which the current increased with increasing time of electric field application. Possible mechanisms leading to the observed absorption current behaviour in the nanocomposites are discussed with the aid of space charge measurements. The presence of space charge limited conduction (SCLC) and its trap-filled limit is proposed.Keywords: nanocomposites, nanosilica, interface, absorption current, space charge limited conduction. 2 IntroductionThe addition of a nanofiller to a polymer matrix has been shown to be a flexible means of tailoring the dielectric properties of materials [1][2][3] and Chen et al. [19], for example, have emphasized the unsatisfactory nature of our understanding of charge transport mechanisms. In conventional polymeric insulation, charge transport mechanisms are extremely complicated, when compared with many conducting and semiconducting materials [20,21]. In semicrystalline polyethylene, for example, chainfolded lamellar crystals are surrounded by amorphous conformations and there is likely to be a high concentration of traps relating to each of these structural motifs. On the addition of a nanofiller, charge transport mechanisms will become yet more complicated, since the inclusion of nanoparticles will introduce extensive interfacial surfaces between the nanofiller and the polymer. The presence of such interfaces may directly introduce additional nanofiller/polymer trapping sites and/or modify the surrounding polymer morphology, thereby affecting the local density of states within the system.The current flow caused by the action of an applied electric field on charge carriers within a dielectric material can broadly be categorized into three types [22]: the initial current that flows through the material is the capacitive charging current, which causes a dramatic rise at the very beginning of the voltage application. This is followed by a gradual decrease of current, known as the absorption current or the anomalous current. Conventionally, the absorption current decreases slowly until it reaches a quasi-steady state, providing a conduction c...

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Section: Discussionmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Lau

Vaughan

Chen

et al. 2016

J. Phys. D: Appl. Phys.

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“…Although often combined, we present the bipolar charge model, the induced dipole moment model and the multicore model under separate headings here. The bipolar charge transport model has been used to describe the charge transport in LDPE and its nanocomposites under an applied electric field ( Figure a) . The behavior of the charges can be described by a set of self‐consistent relationships, involving charge advection‐reaction, charge transport and spatial time‐dependent potentials (Poisson's equation).…”

Section: Charge Transport Mechanisms In Nanocomposite‐based Insulatiomentioning

confidence: 99%

“…Under an applied electric field, electrons are injected at the cathode and move through the insulating material toward the anode. At a low electric field, Schottky thermionic emission governs the charge injection, where the charge injection can be described by the use of an injection barrier that depends on temperature, the contact potential barrier, the electric field and the dielectric permittivity . In high electric fields, charge injection occurs through field‐emission tunneling.…”

Section: Charge Transport Mechanisms In Nanocomposite‐based Insulatiomentioning

confidence: 99%

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

2017

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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.

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Nanocomposites

Xavier

2022

Thermoplastic Polymer Composites

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Numerical analysis of space charge accumulation and conduction properties in LDPE nanodielectrics

Cited by 76 publications

References 25 publications

Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

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

Nanocomposites

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