Proposal of a multi-core model for polymer nanocomposite dielectrics

Tanaka, Toshikatsu; Kozako, Masahiro; Fuse, Norikazu; Ohki, Yoshimichi

doi:10.1109/tdei.2005.1511092

Cited by 1,096 publications

(640 citation statements)

References 15 publications

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“…Indeed, thanks to the presence of the nanofiller/polymer interfaces [5][6][7][8][9], such material systems have been envisioned as an answer to many high voltage insulation problems [10]. For example, the partial discharge resistance, electrical treeing growth, space charge formation and dielectric breakdown performance of nanodielectrics have been compared with the respective unfilled and microfilled counterparts and worthwhile improvements in such properties have been reported [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…In Equation (6), which applies in the absence of any traps, the mobility has its conventional meaning. However, when traps are present, these will influence charge transport dynamics since the number of charge carriers available for conduction will be reduced by the factor , which corresponds to the ratio of free charge carriers to trapped charge carriers [38].…”

Section: Introductionmentioning

confidence: 99%

“…However, since the concept of dielectric nanocomposites was first introduced by Lewis in 1994 [17], the essential characteristics of this class of material have been associated with variations in the "intensity" I [5] of properties associated with local interfacial features, such that the extent of the interface/interphase is then defined by the local spatial variation in I. 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: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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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show abstract

“…Furthermore, many studies have claimed that interactions between nanoparticles and the polymer host matrix result in the formation of an interfacial zone or interphase layer with modified polymeric chain dynamics [18,19], alignment [20,21], or morphology [22]. Commonly, such models were proposed to interpret the unexpectedly significant impact of adding a small amount of nanofiller on one or more of the properties of the resulting composites, where two-component effective medium theories cannot explain such effect; some workers have termed this a nanoeffect [23].…”

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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“…Once dispersed in a homogeneous manner, they can generate a region called interphase without a region of internal stress and very often nanocomposites are multifunctional. Once obtained the state of interphase percolation, the whole polymer matrix will be modified, and therefore it is a material with maximum performance in the use of nanoparticles [3].…”

Section: Introductionmentioning

confidence: 99%

Influence of mixing methods on the properties of high density polyethylene nanocomposites with different carbon nanoparticles

et al. 2017

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In this paper, nanocomposites with multiwalled carbon nanotubes (MWCNT) or graphene nanosheets were prepared using a high density polyethylene (HDPE) matrix. Two different processes were employed: a solution method and a melt mixing method. The crystallinity index of the HDPE showed similar levels in nanocomposites after the addition of carbon nanotubes. It can be seen that the preparation process modified the degree of crystallinity of the HDPE matrix with graphene nanosheets. Nanocomposites prepared by the solution method showed a decrease in the crystallinity index. The addition of carbon nanotubes led to an increase of Young´s Modulus with an increase in the MWCNT quantity, regardless of the preparation process used, with a 22.8 % increase for composites with 0.5 wt% of CNTs. The nanocomposites with graphene nanosheets exhibited a different behavior with each mixing method. Nanocomposites prepared by the solution method showed a higher Young´s Modulus than those prepared by melt mixing. Results of transmission electronic microscopy and field emission scanning electronic microscopy indicated homogeneous dispersion for carbon nanotubes in melt mixing. Graphene nanocomposites showed some agglomerates, with smaller platelets in the nanocomposites prepared by solution mixing compared to that prepared by the melt mixing.

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Proposal of a multi-core model for polymer nanocomposite dielectrics

Cited by 1,096 publications

References 15 publications

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

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

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

Influence of mixing methods on the properties of high density polyethylene nanocomposites with different carbon nanoparticles

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