Space-charge trapping and conduction in LDPE, HDPE and XLPE

Montanari, Gian Carlo; Mazzanti, G.; Palmieri, F.; Motori, A.; Perego, G.; Serra, Stefano

doi:10.1088/0022-3727/34/18/325

Cited by 181 publications

(98 citation statements)

References 22 publications

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“…Comparison of this with published data demonstrates that it falls within the measured range for a series of polyethylenes [51], suggesting that the analysis is not unreasonable. Evidently, all the nanocomposites are characterized by a higher charge carrier mobility than the unfilled polyethylene.…”

Section: Absorption Current Measurements At 40 Kv (Dc) MM -1supporting

confidence: 71%

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: Absorption Current Measurements At 40 Kv (Dc) MM -1supporting

confidence: 71%

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 transport of charge to an extracting electrode or a region where neutralisation can take place should thus depend upon the time dependent space charge density. The derivation of an expression for the effective charge mobility during space charge decay that was presented in [10,11] attempted to take account of this effect in a way that would be generally applicable. However, the existence of a spatial distribution in space charge that may alter during the decay process makes it impossible to obtain a solution without the use of approximations, though their choice may be simplified when only the charge density and not the distribution alters [20].…”

Section: Influence Of Space Charge Field On De-trappingmentioning

confidence: 99%

“…In this case a geometrically divergent field was investigated and therefore it could be expected that on de-trapping the main part of the injected charge would move rapidly to the neighbouring injecting electrode for extraction, rather than travel to the planar counter-electrode. The assumption that space charge decay was governed by the transport of charges to the electrodes for neutralisation has recently been used to derive an approximate expression allowing the time dependent mobility of such charges during the decay process to be extracted from the time dependent space charge magnitude [10,11]. The results for cross-linked polyethylene (XLPE) imply an effective mobility governed by trap-to-trap hopping between ever deeper traps as the remaining space charge density decreases.…”

Section: Introductionmentioning

confidence: 99%

Decay of space charge in a glassy epoxy resin following voltage removal

Dissado

Griseri

Peasgood

et al. 2006

IEEE Trans. Dielect. Electr. Insul.

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This is the unspecified version of the paper.This version of the publication may differ from the final published version. Permanent repository link ABSTRACTThe PEA technique is used to measure the distribution of space charge in an epoxy resin after polarisation for one week at an applied field of 7.14kV/mm over a range of temperatures. The decay of the space charge is followed for times up to 114 hours after removal of the voltage and analysed in terms of a number of alternative decay mechanisms. It is shown that the rate-determining stage of the decay mechanism is that of a thermally activated process that has been associated with charge de-trapping. At times greater than 10 2 s the de-trapping process behaves as though the space charge field does not exist and the retention time of the space charge depends only upon the depth of the deepest occupied traps and the temperature.

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“…It has been argued that added fillers can provide additional trap states that can either reduce or enhance the carrier mobility depending on the trap depth 5 . Though different in the elementary process of charge transport, these models all successfully predict the super-linear current-voltage (I-V) relationship in the high field regime that has been observed in many polymer systems with or without fillers [6][7][8] . Distinguishing between these models can be difficult and a unified understanding is still lacking.…”

Section: Introductionmentioning

confidence: 99%

On the nature of high field charge transport in reinforced silicone dielectrics: Experiment and simulation

Huang

Schadler

2016

Journal of Applied Physics

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The high field charge injection and transport properties in reinforced silicone dielectrics were investigated by measuring the time-dependent space charge distribution and the current under dc conditions up to the breakdown field, and were compared with properties of other dielectric polymers. It is argued that the energy and spatial distribution of localized electronic states are crucial to determining these properties for polymer dielectrics. Tunneling to localized states likely dominates the charge injection process. A transient transport regime arises due to the relaxation of charge carriers into deep traps at the energy band tails, and is successfully verified by a Monte Carlo simulation using the multiple-hopping model. The charge carrier mobility is found to be highly heterogeneous due to non-uniform trapping. The slow moving electron packet exhibits a negative field dependent drift velocity possibly due to the spatial disorder of traps.

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Space-charge trapping and conduction in LDPE, HDPE and XLPE

Cited by 181 publications

References 22 publications

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

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

Decay of space charge in a glassy epoxy resin following voltage removal

On the nature of high field charge transport in reinforced silicone dielectrics: Experiment and simulation

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