Modification of electrical properties and performance of EVA and PP insulation through nanostructure by organophilic silicates

Montanari, Gian Carlo; Fabiani, Davide; Palmieri, F.; Kaempfer, Dirk; Thomann, Ralf; Mülhaupt, Rolf

doi:10.1109/tdei.2004.1349780

Cited by 209 publications

(100 citation statements)

References 30 publications

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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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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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“…It is shown by recent literature contributions that nanocomposites contribute to improve significantly electrical insulation characteristics (1)- (3) . Their behavior has been investigated through various techniques, such as Transmission Electron Microscopy, TEM, Wide-Angle X-Ray Spectroscopy, WAXS, mechanical strength, conduction current, space charge, partial discharges and voltage breakdown tests (4)- (11) .…”

Section: Introductionmentioning

confidence: 99%

“…Their behavior has been investigated through various techniques, such as Transmission Electron Microscopy, TEM, Wide-Angle X-Ray Spectroscopy, WAXS, mechanical strength, conduction current, space charge, partial discharges and voltage breakdown tests (4)- (11) . It has been proved that the dispersion of an inorganic phase in the polymeric matrix may improve voltage endurance (9)- (12) , dielectric strength (4), (12)- (14) , thermal stability (2)(5) (15) and mechanical properties (1) (16) in relation to particle size and arrangement on nanometric scale. Contrasting information can be found in literature regarding to polarization behavior.…”

Section: Introductionmentioning

confidence: 99%

Polarization Processes of Nanocomposite Silicate-EVA and PP Materials

Montanari

Palmieri

Testa³

et al. 2006

IEEJ Trans. FM

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Recent works indicate that polypropylene (PP) and ethylene-vinylacetate (EVA) filled by nanosilicates may present low content of space charge and high electric strength. It has been proved that the dispersion of an inorganic phase in the polymeric matrix may improve voltage endurance, dielectric strength, thermal stability and mechanical properties in relation to particle size and arrangement on nanometric scale. Two polymeric materials, widely employed as electrical insulation for apparatus involved in energy transport, that is, ethylene vinylacetate (EVA) and isotactic polypropylene (PP) are examined. The nanofiller consists of an organophilic layered silicate (MEE), the purified MEE will be named MEE-w.Dielectric spectroscopy in time and frequency domain constitutes a useful tool for electrical insulation evaluation and diagnosis, and it can contribute to the understanding of electrical behaviour of complex solid polymer systems. In this paper, the results of dielectric spectroscopy analysis in time and frequency domain, for purified and unpurified filler nanocomposites, in a wide temperature range, are presented.Frequency-domain dielectric measurements were performed in order to appreciate the relaxation processes taking place at lower temperatures (-20 to 20 °C) over the 10 2 -10 6 Hz frequency range.The charging-discharging current measurements, through Fourier time to frequency data transformation, gave information about the slowest polarisation processes, that are usually hidden by the conduction current contribution. Space charge measurement data are also considered in order to understand the effect of nanostructuration and purification on charge carriers. While the relaxation process of EVA, α process, associated with glass transition of the material amorphous phase, results unchanged from base to nanostructured material (i.e., the nanofiller particles do not affect the chain mobility of the polymer), nanocomposites EVA and PP have shown the rise of a new process at higher temperatures respect to the typical host material processes, as well as a different distribution of relaxation processes. In Fig. 1, that displays the imaginary permittivity of EVA+MEE-w nanocomposite, the loss peaks, due to the α and α' process, can be clearly seen. The α' process can be ascribed to the interaction between the polymer matrix and MEE nanolayers.The temperature location of the process, which approaches the melting region of EVA, and its absence in the pure polymer let us argue that the α' relaxation process can be ascribed to a charge polarization of the Maxwell-Wagner-Sillars type, which is due likely to charge trapping at the interfaces between the nanofiller particles and the polymer. All the presented relaxation processes are thermally-activated and their activation energies, reported in Table 1, were estimated reporting the loss peak frequency and temperature of the isothermal measurements in the Arrhenius plot.The EVA nanocomposite obtained by an unpurified filler has shown a huge increment of real and imaginary...

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“…Polymer matrix/LS nanocomposites exhibit three different configurations: (a) microphase separated composites, where polymer matrix and layered silicates remain immiscible, (b) intercalated structures, where polymer molecules are inserted between the silicate layers, and (c) exfoliated structures, where individual silicate layers are dispersed in the polymer matrix. Polymer matrix nanocomposites are expected to be useful in replacing conventional insulating materials providing tailored performance, by simply controlling the type and the concentration of nanoinclusions [5][6][7][8]. 'Nanodielectrics' is a rather new term associating dielectrics with nanotechnology [9].…”

mentioning

confidence: 99%

Relaxation phenomena in rubber/layered silicate nanocomposites

Psarras

Gatos²,

Karahaliou³

et al. 2007

Express Polym. Lett.

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The impact of nanomaterials and/or nanostructured materials is well known and well appreciated [1][2][3][4], mostly due to their potential applications based on their thermo-mechanical performance, flame resistance, electrical properties etc. Polymer matrix nanocomposites can be prepared by dispersing a small amount of nanometer size filler within the host medium. Rubber/Layered Silicate (LS) nanocomposites are increasingly attracting scientific and technological attention, because of the high reinforcing efficiency of the LS, even at very low loading. Polymer matrix/LS nanocomposites exhibit three different configurations: (a) microphase separated composites, where polymer matrix and layered silicates remain immiscible, (b) intercalated structures, where polymer molecules are inserted between the silicate layers, and (c) exfoliated structures, where individual silicate layers are dispersed in the polymer matrix. Polymer matrix nanocomposites are expected to be useful in replacing conventional insulating materials providing tailored performance, by simply controlling the type and the concentration of nanoinclusions [5][6][7][8]. 'Nanodielectrics' is a rather new term associating dielectrics with nanotechnology [9]. Nanoinclusions could be able to serve as inherent nanocapacitors. Charging and discharging 837 * Corresponding author, e-mail: G.C.Psarras@upatras.gr © BME-PT and GTE Abstract. Broadband Dielectric Spectroscopy (BDS) is employed in order to investigate relaxation phenomena occurring in natural rubber (NR), polyurethane rubber (PUR) and PUR/NR blend based nanocomposites, reinforced by 10 parts per hundred (phr) Layered Silicates (LS). Nanocomposites and matrices were examined under identical conditions in a wide frequency (10 -1 to 10 6 Hz) and temperature (-100 to 50°C) range. Experimental data are analyzed in terms of electric modulus formalism. The recorded relaxation phenomena include contributions from both the polymer matrices and the nanofiller. Natural rubber is a non-polar material and its performance is only slightly affected by the presence of layered silicates. Polyurethane rubber exhibits four distinct relaxation processes attributed, with ascending relaxation rate, to Interfacial Polarization (IP), glass/rubber transition (α-mode), local motions of polar side groups and small segments of the polymer chain (β, γ-mode). The same processes have been detected in all systems containing PUR. IP is present in all nanocomposites being the slowest recorded process. Finally, pronounced interfacial relaxation phenomena, occurring in the PUR+10 phr LS spectra, are attributed to nanoscale effects of intercalation and exfoliation.Keywords : polymer composites, nanocomposites, dielectric spectroscopy, relaxations, rubber eXPRESS Polymer Letters Vol.1, No.12 (2007) [837][838][839][840][841][842][843][844][845] Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2007.116 under control the embedded in a matrix nanocapacitors, defines an energy storing procedure at the nanoscal...

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Modification of electrical properties and performance of EVA and PP insulation through nanostructure by organophilic silicates

Cited by 209 publications

References 30 publications

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

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

Polarization Processes of Nanocomposite Silicate-EVA and PP Materials

Relaxation phenomena in rubber/layered silicate nanocomposites

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