Candidate mechanisms controlling the electrical characteristics of silica/XLPE nanodielectrics

Roy, Mervyn; Nelson, J. K.; MacCrone, R.K.; Schadler, Linda S.

doi:10.1007/s10853-006-0413-0

Cited by 236 publications

(185 citation statements)

References 21 publications

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“…The change in the exponent seen in all the nanocomposites on entering Phase II can be interpreted in a number of ways. First, it could indicate a change in the dominant absorption current mechanism, which may be related to interfacial polarization effects, as proposed elsewhere [28,56]. Second, Smith [24] suggested that the mobility of charge carriers could be highly dependent upon the trapping and release of charges from deep traps, in addition to the underlying current associated with the large number of shallower traps present within the system.…”

Section: Discussionmentioning

confidence: 84%

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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: 84%

“…The change from homocharge to heterocharge near the cathode is likely to have a marked effect on charge injection processes and, consequently, should affect many different electrical factors [52,53].…”

Section: Space Charge Dynamicsmentioning

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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“…Since most of polymer nanocomposites are electrically insulating and the electrical power industry already uses large quantities of polymeric materials as electrical insulation, the efforts to determine whether the PNCs could also posses better dielectric properties and find wider application in the electrical industry area were inevitable. Some of the recently published data suggest that the PNCs do in fact have better electrical breakdown strength, surface and volume resistivity, space charge mitigation characteristics [1][2][3], resistance to partial discharges [4][5][6][7][8], etc.…”

Section: Space Charge Evolution In Polypropylene Containingmentioning

confidence: 99%

Space charge evolution in polypropylene containing synthetic and natural organoclays

Dakka

Bulinski

Bamji

2010

2010 Annual Report Conference on Electrical Insulation and Dielectic Phenomena

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“…Nanoparticle dispersion usually imposes a challenge for obtaining actual nanodielectric systems, where the nanoparticles, due to their large specific surface area and surface tension forces, tend to agglomerate, producing a sub-microcomposites [11,12]. Many researchers have tried to overcome this by treating the nanofiller with matrix-compatible functionalities [13][14][15][16][17]. However, this treatment brings other parameters into play, such as changing the particle surface chemistry and water absorption, and thus, complicates the analysis of the influence of particle dispersion.…”

Section: Introductionmentioning

confidence: 99%

Influence of filler/matrix interactions on resin/hardener stoichiometry, molecular dynamics, and particle dispersion of silicon nitride/epoxy nanocomposites

et al. 2017

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The addition of nanofillers can have a significant influence on the resin stoichiometry of thermosetting polymer systems. Based on differential scanning calorimetry (DSC) results, it is estimated that the inclusion of 2 and 5 wt% of silicon nitride nanofiller displaces the resin/hardener stoichiometry of an epoxy/amine network by 6.5 and 18%, respectively. Dielectric spectroscopy results confirm the above findings, in that the spectra of the nanocomposite samples were found to be equivalent to the spectra of unfilled samples when the above stoichiometric effect was taken into account. Therefore, this study provides clear evidence that the presence of a nanofiller can directly and significantly affect the curing process of an epoxy network. Consequently, this should always be considered when introducing nanofillers into thermosetting matrices. These results indicate the presence of covalent bonding between the nanoparticles and the surrounding polymer and, therefore, provide an opportunity to explore the influence of this bonding on the molecular dynamics of the polymer layer around the particles. However, the obtained DSC and dielectric spectroscopy results suggest that, in the system considered here, either the covalent bonding does not have an appreciable influence on the segmental dynamics of the polymer, as revealed by these techniques, or that the thickness of the affected layer is less than 1 nm and therefore too small to be distinguished from experimental uncertainties.

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Candidate mechanisms controlling the electrical characteristics of silica/XLPE nanodielectrics

Cited by 236 publications

References 21 publications

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

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

Space charge evolution in polypropylene containing synthetic and natural organoclays

Influence of filler/matrix interactions on resin/hardener stoichiometry, molecular dynamics, and particle dispersion of silicon nitride/epoxy nanocomposites

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