scholarly journals Improved Direct Current Electrical Properties of Crosslinked Polyethylene Modified with the Polar Group Compound

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1624 ◽  
Author(s):  
Chengcheng Zhang ◽  
Jianxin Chang ◽  
Hongyu Zhang ◽  
Chunyang Li ◽  
Hong Zhao
Keyword(s):  
Electrical Properties ◽  
Space Charge ◽  
Functional Groups ◽  
Direct Current ◽  
Breakdown Strength ◽  
Photoelectron Spectra ◽  
Polar Group ◽  
Charge Accumulation ◽  
Scanning Calorimetry ◽  
Polar Functional Groups

To suppress space charge accumulation and improve direct current (DC) electrical properties of insulation materials, crosslinked polyethylene modified with 2-(4-benzoyl-3-hydroxyphenoxy) ethyl acrylate (XLPE/BHEA) containing polar functional groups was prepared by melt blending. The gel content, thermal elongation, tensile strength, elongation at break, elasticity modulus, differential scanning calorimetry (DSC) and X-ray photoelectron spectra (XPS) measurement results demonstrated that the BHEA could slightly enhance the crosslinking of polyethylene (PE) and affect the mechanical properties and crystallization of XLPE, and the BHEA molecule was not easy to precipitate from XLPE after the crosslinking process. XLPE modified with 3.0 phr (parts per hundreds by weight) BHEA could effectively suppress space charge accumulation, reduce DC conduction and improve DC breakdown strength of XLPE at a higher temperature. Deeper traps were introduced in XLPE/BHEA composites due to the polar functional groups in BHEA, which could raise the potential charge injection barrier and reduce the charge carrier number and mobility to suppress space charge accumulation and reduce the conduction current density.

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

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 592 ◽  
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.

scholarly journals Investigation of the Space Charge and DC Breakdown Behavior of XLPE/α-Al2O3 Nanocomposites

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1333
Author(s):  
Xiangjin Guo ◽  
Zhaoliang Xing ◽  
Shiyi Zhao ◽  
Yingchao Cui ◽  
Guochang Li ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Space Charge ◽  
Direct Current ◽  
Breakdown Strength ◽  
Charge Carrier Mobility ◽  
Charge Accumulation ◽  
Polyethylene Matrix ◽  
Uniform Size ◽  
Α Al2o3 ◽  
Surface Modified

This paper describes the effects of α-Al2O3 nanosheets on the direct current voltage breakdown strength and space charge accumulation in crosslinked polyethylene/α-Al2O3 nanocomposites. The α-Al2O3 nanosheets with a uniform size and high aspect ratio were synthesized, surface-modified, and characterized. The α-Al2O3 nanosheets were uniformly distributed into a crosslinked polyethylene matrix by mechanical blending and hot-press crosslinking. Direct current breakdown testing, electrical conductivity tests, and measurements of space charge indicated that the addition of α-Al2O3 nanosheets introduced a large number of deep traps, blocked the charge injection, and decreased the charge carrier mobility, thereby significantly reducing the conductivity (from 3.25 × 10−13 S/m to 1.04 × 10−13 S/m), improving the direct current breakdown strength (from 220 to 320 kV/mm) and suppressing the space charge accumulation in the crosslinked polyethylene matrix. Besides, the results of direct current breakdown testing and electrical conductivity tests also showed that the surface modification of α-Al2O3 nanosheets effectively improved the direct current breakdown strength and reduced the conductivity of crosslinked polyethylene/α-Al2O3 nanocomposites.

scholarly journals Evaluation of graphene/crosslinked polyethylene for potential high voltage direct current cable insulation applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuan Li ◽  
Guangya Zhu ◽  
Kai Zhou ◽  
Pengfei Meng ◽  
Guodong Wang
Keyword(s):  
Space Charge ◽  
High Voltage ◽  
Direct Current ◽  
Tensile Yield Strength ◽  
Scanning Calorimetry ◽  
Crosslinking Degree ◽  
High Voltage Direct Current ◽  
Water Tree ◽  
Mechanical And Electrical Properties ◽  
Aging Test

AbstractThis paper evaluates the potential usage of graphene/crosslinked polyethylene (graphene/XLPE) as the insulating material for high voltage direct current (HVDC) cables. Thermal, mechanical and electrical properties of blends with/without graphene were evaluated by differential scanning calorimetry (DSC), tensile strength, DC conductivity, space charge measurements and water tree aging test. The results indicate that 0.007–0.008% weight amount of graphene can improve the mechanical and electrical insulation properties of XLPE blends, namely higher tensile/yield strength, improved space charge distribution, and shorter/fewer water tree branches. The improvements mainly attribute to the high stiffness of graphene, deep traps introduced by the interaction zones of graphene and XLPE, and the blockage effect of graphene within XLPE. For thermal performance of XLPE blends, graphene nano-fillers have but limited improvement. The crystallinity of the blends barely changes with the addition of graphene. However, the crosslinking degree increases as the additive-like amounts of graphene doped. The above findings provide a guide for tailoring lightweight XLPE materials with excellent mechanical and electrical performances by doping them with a small amount of graphene.

scholarly journals Acetylated SEBS Enhanced DC Insulation Performances of Polyethylene

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1033 ◽  
Author(s):  
Wei Dong ◽  
Xuan Wang ◽  
Zaixing Jiang ◽  
Bo Tian ◽  
Yuguang Liu ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Field Strength ◽  
Space Charge ◽  
Aromatic Compounds ◽  
Breakdown Strength ◽  
Charge Accumulation ◽  
New Approach ◽  
Functional Units ◽  
Poly Ethylene ◽  
Accumulation Characteristics

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.

scholarly journals Characterization of Polypropylene Modified by Blending Elastomer and Nano-Silica

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1321 ◽  
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.

Trap Property and Charge Transmission in PE

2020 ◽  
pp. 129-155
Keyword(s):  
Charge Transfer ◽  
Electrical Properties ◽  
Space Charge ◽  
Transfer Process ◽  
Breakdown Strength ◽  
Electrical Performance ◽  
Trap Level ◽  
Charge Transfer Process ◽  
Direct Current Conductivity ◽  
Trapping Process

The electrical properties of the dielectric are achieved by affecting the charge transfer process. The trap characteristics have an important influence on the electrical properties of the dielectric by affecting the charge transfer process. Aggregation and trap level characteristics of nanographene on low density polyethylene (LDPE). The direct current conductivity, breakdown strength, trap level distribution, space charge distribution, and charge mobility of nanocomposites were investigated. The experimental results show that the interface region between graphene and polymer introduces many deep traps in the forbidden band of nanocomposites, which can reduce the trapping process of charge and inhibit the accumulation of space charge. This indicates that the addition of nanoscale graphene has a significant improvement in the electrical performance of high voltage DC cables, which will provide a reference for production and application.

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

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1359 ◽  
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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