Enhanced dielectric properties due to space charge-induced interfacial polarization in multilayer polymer films

Acetophenone can significantly improve the dielectric properties of polyethylene (PE) insulation materials. However, it easily migrates from the PE due to its poor compatibility with the material, which limits its application. In this paper, the functional units of acetophenone were modified in polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) by an acetylation reaction, and SEBS was used as the carrier to inhibit the migration of acetophenone. The number of functional units in the acetylated SEBS (Ac-SEBS) was measured by 1H NMR and the effect of the acetylation degree of SEBS on its compatibility with PE was studied. Meanwhile, the effects of Ac-SEBS on PE’s direct current (DC) breakdown strength and space charge accumulation characteristics were investigated. It is demonstrated that Ac-SEBS can significantly improve the field strength of the DC breakdown and inhibit the accumulation of space charge in the PE matrix. This work provides a new approach for the application of aromatic compounds as voltage stabilizers in DC insulation cable materials.

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Enhanced Insulation Performances of Crosslinked Polyethylene Modified by Chemically Grafting Chloroacetic Acid Allyl Ester

Polymers ◽

10.3390/polym11040592 ◽

2019 ◽

Vol 11 (4) ◽

pp. 592 ◽

Cited By ~ 3

Author(s):

Xin-Dong Zhao ◽

Wei-Feng Sun ◽

Hong Zhao

Keyword(s):

Space Charge ◽

Dielectric Breakdown ◽

Breakdown Strength ◽

Chloroacetic Acid ◽

Dielectric Materials ◽

Electrical Insulation ◽

Polar Group ◽

Charge Accumulation ◽

Allyl Ester ◽

Electrical Insulation Properties

Modified crosslinked polyethylene (XLPE) with appreciably enhanced DC electrical insulation properties has been developed by chemical modification of grafting chloroacetic acid allyl ester (CAAE), exploring the trapping mechanism of charge transport inhibition. The bound state traps deriving from grafted molecule are analyzed by first-principles calculations, in combination with the electrical DC conductivity and dielectric breakdown strength experiments to study the underlying mechanism of improving the electrical insulation properties. In contrast to pure XLPE, the XLPE-graft-CAAE represents significantly suppressed space charge accumulation, increased breakdown strength, and reduced conductivity. The substantial deep traps are generated in XLPE-graft-CAAE molecules by polar group of grafted CAAE and accordingly decrease charge mobility and raise charge injection barrier, consequently suppressing space charge accumulation and charge carrier transport. The well agreement of experiments and quantum mechanics calculations suggests a prospective material modification strategy for achieving high-voltage polymer dielectric materials without nanotechnology difficulties as for nanodielectrics.

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Characterization of Polypropylene Modified by Blending Elastomer and Nano-Silica

Materials ◽

10.3390/ma11081321 ◽

2018 ◽

Vol 11 (8) ◽

pp. 1321 ◽

Cited By ~ 14

Author(s):

Xiaohong Chi ◽

Lu Cheng ◽

Wenfeng Liu ◽

Xiaohong Zhang ◽

Shengtao Li

Keyword(s):

Dielectric Properties ◽

Space Charge ◽

Power Transmission ◽

Breakdown Strength ◽

Tensile Tests ◽

Mechanical Analysis ◽

Insulation Material ◽

Nano Silica ◽

Scanning Calorimetry ◽

High Voltage Direct Current

Polypropylene (PP) contains promising application prospects in thermoplastic cables for high voltage direct current (HVDC) power transmission because of its outstanding thermal and dielectric properties. However, the problem of poor toughness and space charge has restricted the application of pure PP in HVDC cables. In this paper, polyolefin elastomer (POE) and nano-silica were blended thoroughly and added into a PP mixture by a melting method. Scanning electron microscopy (SEM) was employed to observe the dispersion of POE and nanoparticles. Thermal properties were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Mechanical properties were evaluated by tensile tests. The elastomeric properties of composites were improved as the dispersed POE could transfer and homogenize external mechanical forces. DC breakdown results showed that the fail strength of composite with 10 phr POE and 1 phr nano-silica was obviously enhanced. The pulsed electro-acoustic (PEA) results showed that the injection and accumulation of space charge was increased by the introduction of POE, while it was restrained by the collective effect caused by nano-silica filling. X-ray diffraction (XRD) spectrograms showed that secondary ordered structures existed in the composites of PP, POE, and nano-silica, and that the ordered structure around the nanoparticles contributed to the enhancement of breakdown strength. The mechanical and dielectric properties were modified synergistically, which made the modified PP a propitious insulation material for HVDC cables.

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Crystallization and Dielectric Properties of MWCNT /Poly(1-Butene) Composite Films by a Solution Casting Method

Materials ◽

10.3390/ma13030755 ◽

2020 ◽

Vol 13 (3) ◽

pp. 755

Author(s):

Lingfei Li ◽

Qiu Sun ◽

Xiangqun Chen ◽

Yongjun Xu ◽

Zhaohua Jiang

Keyword(s):

Dielectric Constant ◽

Dielectric Properties ◽

Dielectric Loss ◽

Breakdown Strength ◽

Composite Films ◽

Conductive Filler ◽

Interfacial Polarization ◽

Solution Casting ◽

Casting Method ◽

Solution Casting Method

In this work, poly(1-butene) (PB-1) composite films with multi-walled carbon nanotubes (MWCNT) were prepared by a solution casting method. The relationship between the dielectric properties and the crystal transformation process of the films was investigated. It was indicated that there were two crystal forms of I and II of PB-1 during the solution crystallization process. With the prolongation of the phase transition time, form II was converted into form I. The addition of the conductive filler (MWCNT) accelerated the rate of phase transformation and changed the nucleation mode of PB-1. The presence of crystal form I in the system increased the breakdown strength and the dielectric constant of the films and reduced the dielectric loss, with better stability. In addition, the dielectric constant and the dielectric loss of the MWCNT/PB-1 composite films increased with the addition of MWCNT, due to the interfacial polarization between MWCNT and PB-1 matrix. When the mass fraction of the MWCNT was 1.0%, the composite film had a dielectric constant of 43.9 at 25 °C and 103 Hz, which was 20 times that of the original film.

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Dielectric and Thermal Conductivity of Epoxy Resin Impregnated Nano-h-BN Modified Insulating Paper

Polymers ◽

10.3390/polym11081359 ◽

2019 ◽

Vol 11 (8) ◽

pp. 1359 ◽

Cited By ~ 7

Author(s):

Hongda Yang ◽

Qingguo Chen ◽

Xinyu Wang ◽

Minghe Chi ◽

Heqian Liu ◽

...

Keyword(s):

Thermal Conductivity ◽

Dielectric Properties ◽

Space Charge ◽

Epoxy Resin ◽

Direct Current ◽

Heat Conductivity ◽

Power Transmission ◽

Breakdown Strength ◽

Hexagonal Boron Nitride ◽

Insulating Paper

Epoxy resin-impregnated insulation paper (RIP) composites are used as the inner insulation of dry condenser bushing in the ultra-high voltage direct current (UHVDC) power transmission system. To improve the dielectric properties and heat conductivity of RIP, hexagonal boron nitride (h-BN) nano-flakes are added to the insulation paper at concentrations of 0–50 wt % before impregnation with pure epoxy resin. X-ray diffraction (XRD), scanning electron microscopy (SEM) observations, thermal conductivity as well as the typical dielectric properties of direct current (DC) volume conductivity. DC breakdown strength and space charge characteristics were obtained. The maximum of nano-h-BN modified heat conductivity reach 0.478 W/(m·K), increased by 139% compared with unmodified RIP. The DC breakdown electric field strength of the nano-h-BN modified RIP does not reduce much. The conductivity of nano-h-BN modified is less sensitive to temperature. As well, the space charge is suppressed when the content is 50 wt %. Therefore, the nano-h-BN modified RIP is potentially useful in practical dry DC bushing application.

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Research on DC dielectric properties of polyaniline nanofibers/LDPE composites

High Performance Polymers ◽

10.1177/0954008316680278 ◽

2016 ◽

Vol 30 (1) ◽

pp. 76-81 ◽

Cited By ~ 2

Author(s):

Changming Li ◽

Sixu Duan ◽

Chengcheng Zhang ◽

Jian Zhang ◽

Baozhong Han

Keyword(s):

Space Charge ◽

Breakdown Strength ◽

Dc Conductivity ◽

Low Density Polyethylene ◽

Low Density ◽

Polyaniline Nanofibers ◽

Pani Nanofibers ◽

Space Charges ◽

Space Charge Distribution ◽

Ldpe Composites

In this article, polyaniline (PANI) nanofibers were prepared and added to low-density polyethylene (LDPE) to produce PANI nanofibers/LDPE composites. LDPE and the composites were tested for direct current (DC) conductivity, breakdown strength, and space charge characteristics. The results suggested that DC breakdown strength of PANI nanofibers/LDPE composites significantly declined once PANI was added, and the decline was more evident with the increase of PANI nanofibers. Meanwhile, the addition of PANI nanofibers contributed to a decrease in the conductivity of LDPE. As the content of PANI nanofibers increased, the conductivity of the composites declined first and then raised. DC conductivity properties of LDPE could be improved by adding an appropriate amount of PANI nanofibers. Compared with LDPE, the space charge distribution was changed in LDPE due to the addition of PANI nanofibers. With the increase of content of PANI nanofibers, the amount of space charges close to the electrodes decreased gradually.

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Enhanced Dielectric Performance of P(VDF-HFP) Composites with Satellite–Core-Structured Fe2O3@BaTiO3 Nanofillers

Polymers ◽

10.3390/polym11101541 ◽

2019 ◽

Vol 11 (10) ◽

pp. 1541 ◽

Cited By ~ 2

Author(s):

Yongchang Jiang ◽

Zhao Zhang ◽

Zheng Zhou ◽

Hui Yang ◽

Qilong Zhang

Keyword(s):

Dielectric Constant ◽

Dielectric Properties ◽

Flexible Electronics ◽

Vinylidene Fluoride ◽

Breakdown Strength ◽

Composite Films ◽

Interfacial Polarization ◽

Dielectric Materials ◽

Dielectric Performance ◽

High Dielectric

Polymer dielectric materials are extensively used in electronic devices. To enhance the dielectric constant, ceramic fillers with high dielectric constant have been widely introduced into polymer matrices. However, to obtain high permittivity, a large added amount (>50 vol%) is usually needed. With the aim of improving dielectric properties with low filler content, satellite–core-structured Fe2O3@BaTiO3 (Fe2O3@BT) nanoparticles were fabricated as fillers for a poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix. The interfacial polarization effect is increased by Fe2O3 nanoparticles, and thus, composite permittivity is enhanced. Besides, the satellite–core structure prevents Fe2O3 particles from directly contacting each other, so that the dielectric loss remains relatively low. Typically, with 20 vol% Fe2O3@BT nanoparticle fillers, the permittivity of the composite is 31.7 (1 kHz), nearly 1.8 and 3.0 times that of 20 vol% BT composites and pure polymers, respectively. Nanocomposites also achieve high breakdown strength (>150 KV/mm) and low loss tangent (~0.05). Moreover, the composites exhibited excellent flexibility and maintained good dielectric properties after bending. These results demonstrate that composite films possess broad application prospects in flexible electronics.

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Kraft-Pulp Based Material for Electrical Insulation

Proceedings of the Nordic Insulation Symposium ◽

10.5324/nordis.v0i24.2300 ◽

2017 ◽

Cited By ~ 2

Author(s):

Rebecca Hollertz ◽

Lars Wågberg ◽

Claire Pitois

Keyword(s):

Dielectric Properties ◽

Kraft Pulp ◽

Breakdown Strength ◽

Electrical Breakdown ◽

Electrical Equipment ◽

Electrical Insulation ◽

Insulation Material ◽

High Frequency Response ◽

Static Electrification ◽

Electrical Breakdown Strength

<p>The dielectric properties of the electrical insulation material have a significant influence on the performance and reliability of components in electrical equipment. The influence of the chemistry and electronic structure of the different constituents of the kraft pulp (used in electrical insulation) on some dielectric properties is discussed in this paper. The studies and mechanisms discussed indicate that the presence of different wood polymers (cellulose, hemicellulose and lignin), have different effects on dielectric properties (static electrification and high frequency response). Our results show that the dielectric response of lignin is different compared with the response of hemicellulose and cellulose and this is also expected from the chemical structure of the different components. The lignin molecule has a higher polarizability at frequencies of significance for streamer inception and propagation. With spectroscopic ellipsometry measurements it has also been shown that the energy for electronic transitions in this spectral region is lower for lignin. The results also clearly indicate that the role of cellulose, lignin and hemicellulose should be further investigated for improving electrical breakdown strength of paper based insulation materials.</p>

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