Electrical Properties

Fothergill, J.C.

doi:10.1007/978-1-4419-1591-7_7

Cited by 10 publications

(12 citation statements)

References 30 publications

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“…If several tens weight percentage of inorganic microfillers are introduced in polymers, usually the relative permittivity of the composite increases [ 33 ]. This is because fillers have a higher permittivity by nature compared to the base polymers and they cause Maxwell-Wagner interfacial polarization, which provide information about charge trapping associated with internal surfaces and relaxation processes associated with dipole reorientation [ 124 ]. This type of polarization will increase the values of loss tangent, too [ 33 ].…”

Section: Properties Of (Nano)compositesmentioning

confidence: 99%

“…For example at 1 kHz and 393 K, the measured relative permittivities were 9.99 for the base resin, 13.8 for microcomposites and 8.49 for nanocomposites, which is significantly less than the base polymer. This result suggests that the interaction zone, which surrounds the nanoparticles, has a profound effect on the dielectric behavior of nanocomposite and gives rise to limited cooperative movements of dipolar reorientation within them [ 22 , 124 ]. This behavior could be also due to the movement restriction of epoxy molecules end-chains of side-chains by the presence of nanoparticles [ 22 ].…”

Section: Properties Of (Nano)compositesmentioning

confidence: 99%

“…In the mid-range of frequency between 0.1 and 100 Hz, the base resin and the nanocomposites show the same behavior with a small dielectric relaxation, probably due to the bound water [ 22 , 124 ]. The real permittivity of the microcomposite shows a significant increase with decreasing frequency associated with Maxwell-Wagner polarization [ 22 ].…”

Section: Properties Of (Nano)compositesmentioning

confidence: 99%

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Properties of Polymer Composites Used in High-Voltage Applications

et al. 2016

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Abstract:The present review article represents a comprehensive study on polymer micro/nanocomposites that are used in high-voltage applications. Particular focus is on the structure-property relationship of composite materials used in power engineering, by exploiting fundamental theory as well as numerical/analytical models and the influence of material design on electrical, mechanical and thermal properties. In addition to describing the scientific development of micro/nanocomposites electrical features desired in power engineering, the study is mainly focused on the electrical properties of insulating materials, particularly cross-linked polyethylene (XLPE) and epoxy resins, unfilled and filled with different types of filler. Polymer micro/nanocomposites based on XLPE and epoxy resins are usually used as insulating systems for high-voltage applications, such as: cables, generators, motors, cast resin dry-type transformers, etc. Furthermore, this paper includes ample discussions regarding the advantages and disadvantages resulting in the electrical, mechanical and thermal properties by the addition of micro-and nanofillers into the base polymer. The study goals are to determine the impact of filler size, type and distribution of the particles into the polymer matrix on the electrical, mechanical and thermal properties of the polymer micro/nanocomposites compared to the neat polymer and traditionally materials used as insulation systems in high-voltage engineering. Properties such as electrical conductivity, relative permittivity, dielectric losses, partial discharges, erosion resistance, space charge behavior, electric breakdown, tracking and electrical tree resistance, thermal conductivity, tensile strength and modulus, elongation at break of micro-and nanocomposites based on epoxy resin and XLPE are analyzed. Finally, it was concluded that the use of polymer micro/nanocomposites in electrical engineering is very promising and further research work must be accomplished in order to diversify the polymer composites matrices and to improve their properties.

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Section: Properties Of (Nano)compositesmentioning

confidence: 99%

Section: Properties Of (Nano)compositesmentioning

confidence: 99%

Section: Properties Of (Nano)compositesmentioning

confidence: 99%

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Properties of Polymer Composites Used in High-Voltage Applications

et al. 2016

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“…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.…”

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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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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“…The results are discussed in more detail in [53]. For a recent review of this area see the book edited by Keith Nelson [54]. Fig.…”

Section: Nanodielectricsmentioning

confidence: 99%

The coming of Age of HVDC extruded power cables

Fothergill

2014

2014 IEEE Electrical Insulation Conference (EIC)

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This is the accepted version of the paper.This version of the publication may differ from the final published version. Lessons have been learnt from early experiences with AC cables that may be useful in the development of DC cables. DC cables, however, also provide a new set of insulation challenges, primarily associated with the control of conductivity and space charge, which may lead to very high internal electric fields building up in the insulation. Techniques for measuring space charge and conduction are described and discussed in terms of how they might be used to quantify the state of a HVDC cable. Nanodielectrics are likely to play a part in the development of new materials for their insulation. With an understanding of the key processes to control, techniques to control them and new materials, manufacturers now seem keen to embrace extruded power cable technology for HVDC applications. The paper gives a personal perspective on the development of these cables and links it with the author's research over the last 30 years. Permanent repository link:

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Electrical Properties

Cited by 10 publications

References 30 publications

Properties of Polymer Composites Used in High-Voltage Applications

Properties of Polymer Composites Used in High-Voltage Applications

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

The coming of Age of HVDC extruded power cables

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