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 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 Significantly Improved Electrical Properties of Crosslinked Polyethylene Modified by UV-Initiated Grafting MAH

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 62 ◽  
Author(s):  
Xin-Dong Zhao ◽  
Hong Zhao ◽  
Wei-Feng Sun
Keyword(s):  
Electric Fields ◽  
Carrier Transport ◽  
Elevated Temperatures ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Electrical Conductance ◽  
Electrical Current ◽  
Underlying Mechanism ◽  
Polar Group ◽  
Frenkel Effect

Direct current (DC) electrical performances of crosslinked polyethylene (XLPE) have been evidently improved by developing graft modification technique with ultraviolet (UV) photon-initiation. Maleic anhydride (MAH) molecules with characteristic cyclic anhydride were successfully grafted to polyethylene molecules under UV irradiation, which can be efficiently realized in industrial cable production. The complying laws of electrical current varying with electric field and the Weibull statistics of dielectric breakdown strength at altered temperature for cable operation were analyzed to study the underlying mechanism of improving electrical insulation performances. Compared with pure XLPE, the appreciably decreased electrical conductivity and enhanced breakdown strength were achieved in XLPE-graft-MAH. The critical electric fields of the electrical conduction altering from ohm conductance to trap-limited mechanism significantly decrease with the increased testing temperature, which, however, can be remarkably raised by grafting MAH. At elevated temperatures, the dominant carrier transport mechanism of pure XLPE alters from Poole–Frenkel effect to Schottky injection, while and XLPE-graft-MAH materials persist in the electrical conductance dominated by Poole–Frenkel effect. The polar group of grafted MAH renders deep traps for charge carriers in XLPE-graft-MAH, and accordingly elevate the charge injection barrier and reduce charge mobility, resulting in the suppression of DC electrical conductance and the remarkable amelioration of insulation strength. The well agreement of experimental results with the quantum mechanics calculations suggests a prospective strategy of UV initiation for polar-molecule-grafting modification in the development of high-voltage DC cable materials.

scholarly journals Space Charge Accumulation and Decay in Dielectric Materials with Dual Discrete Traps

2019 ◽  
Vol 9 (20) ◽  
pp. 4253 ◽  
Author(s):  
Zhaoliang Xing ◽  
Chong Zhang ◽  
Haozhe Cui ◽  
Yali Hai ◽  
Qingzhou Wu ◽  
...  
Keyword(s):  
Space Charge ◽  
Analytical Solutions ◽  
Charge Injection ◽  
Charge Trapping ◽  
Dielectric Materials ◽  
Dynamic Processes ◽  
Charge Accumulation ◽  
Charge Densities ◽  
Short Period ◽  
Trapped Charge

Charge trapping and de-trapping properties can affect space charge accumulation and electric field distortion behavior in polymers. Dielectric materials may contain different types of traps with different energy distributions, and it is of interest to investigate the charge trapping/de-trapping dynamic processes in dielectric materials containing multiple discrete trap centers. In the present work, we analyze the charge trapping/de-trapping dynamics in materials with two discrete traps in two cases where charges are injected continuously or only for a very short period. The time dependent trapped charge densities are obtained by the integration of parts in the case of continuous charge injection. In the case of instantaneous charge injection, we simplify the charge trapping/de-trapping equations and obtain the analytical solutions of trapped charge densities, quasi-free charge density, and effective carrier mobility. The analytical solutions are in good agreement with the numerical results. Then, the space charge dynamics in dielectric materials with two discrete trapping centers are studied by the bipolar charge transport (BCT) model, consisting of charge injection, charge migration, charge trapping, de-trapping, and recombination processes. The BCT outputs show the time evolution of spatial distributions of space charge densities. Moreover, we also achieve the charge densities at the same position in the sample as a function of time by the BCT model. It is found that the DC poling duration can affect the energy distribution of accumulated space charges. In addition, it is found that the coupling dynamic processes will establish a dynamic equilibrium rather than a thermodynamic equilibrium in the dielectric materials.

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

2017 ◽  
Vol 5 (39) ◽  
pp. 10417-10426 ◽  
Author(s):  
Xinyue Chen ◽  
Jung-Kai Tseng ◽  
Imre Treufeld ◽  
Matthew Mackey ◽  
Donald E. Schuele ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Space Charge ◽  
Polymer Films ◽  
Breakdown Strength ◽  
Interfacial Polarization ◽  
Electrical Insulation ◽  
Space Charges

Interfacial polarization due to space charges enhances electrical insulation and thus breakdown strength for multilayer polymer films.

scholarly journals Crystalline Modification and Its Effects on Dielectric Breakdown Strength and Space Charge Behavior in Isotactic Polypropylene

Polymers ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 406 ◽  
Author(s):  
Ling Zhang ◽  
Yunxiao Zhang ◽  
Yuanxiang Zhou ◽  
Chenyuan Teng ◽  
Zhaowei Peng ◽  
...  
Keyword(s):  
Space Charge ◽  
Isotactic Polypropylene ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Crystalline Modification ◽  
Dielectric Breakdown Strength

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.

Flame Retardancy and Excellent Electrical Insulation Performance of RTV Silicone Rubber

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2854
Author(s):  
Muhammad Tariq Nazir ◽  
Arslan Khalid ◽  
Imrana Kabir ◽  
Cheng Wang ◽  
Juan-Carlos Baena ◽  
...  
Keyword(s):  
Flame Retardancy ◽  
Silicone Rubber ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Volume Resistivity ◽  
Electrical Insulation ◽  
Outdoor Insulation ◽  
Power Frequency ◽  
A Minor ◽  
Rtv Silicone Rubber

Room temperature vulcanized (RTV) silicone rubber filled with aluminum trihydrate (ATH) is substantially engaged in electrical outdoor insulation applications. The pristine silicone rubber is highly combustible. ATH filled silicone rubber offers excellent electrical insulation but lacks in providing adequate flame retardancy. This short communication reports the novel results on improved flame retardancy of pristine and ATH filled silicone rubber whilst retaining the electrical insulation properties to a great extent. Results suggest that the presence of only one percent of graphene nanoplatelets with ATH sharply reduces the heat release rate and rate of smoke release. A minor reduction in dielectric breakdown strength and volume resistivity is noticed. Furthermore, permittivity and dielectric loss at power frequency suggest that a marginal 1% concentration of nanoplatelet with ATH is an excellent approach to fabricate flame retardant silicone rubber with an acceptable electrical insulation level.

scholarly journals Influence of Nanocomposites of LDPE Doped with Nano-MgO by Different Preparing Methods on Its Dielectric Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Wenlong Zhang ◽  
Yajie Dai ◽  
Hong Zhao ◽  
Lidong Zhong
Keyword(s):  
Space Charge ◽  
Applied Field ◽  
Breakdown Strength ◽  
Volume Resistivity ◽  
Charge Accumulation ◽  
Preparation Methods ◽  
Heating Method ◽  
Microwave Assisted ◽  
Microwave Assisted Method ◽  
Better Than

LDPE doped with nano-MgO can effectively suppress the space charge accumulation in the nanocomposite under DC applied field, and this suppression was affected greatly by the prepared nano-MgO particles. In this paper, the influence of nanocomposite of LDPE doped with nano-MgO by using different preparation methods on their space charge, and volume resistivity as well as DC breakdown strength was researched. The results showed that size of nano-MgO prepared by the traditional heating method was about 22.74 nm, while being only about 12.76 nm by the microwave-assisted method. When the nano-MgO content in the composite was 2 wt% by weight, the space charge accumulation in this composite was obviously reduced; meanwhile both the volume resistivity and DC breakdown strength were enhanced. When nano-MgO was prepared by the microwave-assisted method, the electric properties of its LDPE nanocomposite were obviously better than those of nano-MgO prepared by traditional heating method.

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