scholarly journals Enhanced Thermal Conductivity and Dielectric Properties of h-BN/LDPE Composites

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4738
Author(s):  
Lijuan He ◽  
Junji Zeng ◽  
Yuewu Huang ◽  
Xiong Yang ◽  
Dawei Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Space Charge ◽  
Direct Current ◽  
Breakdown Strength ◽  
Hexagonal Boron Nitride ◽  
Electrical Equipment ◽  
Electrical Performance ◽  
Suppression Effect ◽  
Thermally Conductive ◽  
Ldpe Composites

Low-density polyethylene (LDPE), as an excellent dielectric insulating material, is widely used in electrical equipment insulation, whereas its low thermal conductivity limits its further development and application. Hexagonal boron nitride (h-BN) filler was introduced into LDPE to tailor the properties of LDPE to make it more suitable for high-voltage direct current (HVDC) cable insulation application. We employed melt blending to prepare h-BN/LDPE thermally conductive composite insulation materials with different contents. We focused on investigating the micromorphology and structure, thermal properties, and electrical properties of h-BN/LDPE composites, and explained the space charge characteristics. The scanning electron microscope (SEM) results indicate that the h-BN filler has good dispersibility in the LDPE at a low loading (less than 3 phr (3 g of micron h-BN particles filled in 100g of LDPE)), as well as no heterogeneous phase formation. The results of thermal conductivity analysis show that the introduction of h-BN filler can significantly improve the thermal conductivity of composites. The thermal conductivity of the composite samples with 10 phr h-BN particles is as high as 0.51 W/(m·K), which is 57% higher than that of pure LDPE. The electrical performance illustrates that h-BN filler doping can significantly inhibit space charge injection and reduce space charge accumulation in LDPE. The interface effect between h-BN and the substrate reduces the carrier mobility, thereby suppressing the injection of charges of the same polarity and increasing the direct-current (DC) breakdown strength. h-BN/LDPE composite doped with 3 phr h-BN particles has excellent space charge suppression effect and high DC breakdown strength, which is 14.3% higher than that of pure LDPE.

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.

scholarly journals Dielectric and Thermal Conductivity Characteristics of Epoxy Resin-Impregnated H-BN/CNF-Modified Insulating Paper

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2080
Author(s):  
Hongda Yang ◽  
Qingguo Chen ◽  
Xinyu Wang ◽  
Minghe Chi ◽  
Jinfeng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Space Charge ◽  
Epoxy Resin ◽  
Breakdown Strength ◽  
Hexagonal Boron Nitride ◽  
Cellulose Fiber ◽  
High Voltage Direct Current ◽  
Insulating Paper ◽  
Nano Cellulose ◽  
Scanning Electron

High-voltage direct-current (HVDC) dry bushing capacitor-core insulation is composed of epoxy resin-impregnated insulating paper (RIP). To improve the thermal conductivity, breakdown strength, and space charge characteristics of RIP, 0.1 wt % nano-cellulose fiber (CNF)-modified RIP (CNF/RIP), 2.5–30 wt % hexagonal boron nitride (h-BN)-modified RIP (h-BN/RIP), and 2.5–30 wt % h-BN + 0.1 wt % CNF-modified RIP (h-BN + 0.1 wt % CNF/RIP) were prepared. Scanning electron microscopy (SEM) was implemented; the thermal conductivity, DC conductivity, DC breakdown strength, and space charge characteristics were tested. The maximum thermal conductivity of h-BN + 0.1 wt % CNF/RIP was 0.376 W/m.K with a h-BN content of 30 wt %. The thermal conductivity was 85.2% higher than that of unmodified RIP. The breakdown strength and charge suppression were the best in the case of 10 wt % h-BN + 0.1 wt % CNF/RIP. The maximum breakdown strength was 11.2% higher than that of unmodified RIP. These results can play a significant role in the research and development of insulation materials for HVDC dry bushing.

Antimicrobial hexagonal boron nitride nanoplatelet composites for the thermal management of medical electronic devices

2019 ◽  
Vol 3 (11) ◽  
pp. 2455-2462 ◽  
Author(s):  
Si-Wei Xiong ◽  
Pan Zhang ◽  
Yu Xia ◽  
Pei-Gen Fu ◽  
Jing-Gang Gai
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Thermal Management ◽  
Hexagonal Boron Nitride ◽  
Electronic Devices ◽  
E Coli ◽  
Thermally Conductive ◽  
Medical Electronic

We developed a thermally conductive and antimicrobial QACs@h-BN/LLDPE composites for thermal management of medically electronic devices, it was approximately 100% against both E. coli and S. aureus and its thermal conductivity can reach 1.115 W m−1 K−1.

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 Aerogel Perfusion-Prepared h-BN/CNF Composite Film with Multiple Thermally Conductive Pathways and High Thermal Conductivity

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1051 ◽  
Author(s):  
Xiu Wang ◽  
Zhihuai Yu ◽  
Liang Jiao ◽  
Huiyang Bian ◽  
Weisheng Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Composite Film ◽  
Hexagonal Boron Nitride ◽  
Traditional Approach ◽  
Synthetic Polymer ◽  
Electrical Insulation ◽  
High Thermal Conductivity ◽  
Polymer Materials ◽  
Thermally Conductive ◽  
Electrical Insulation Properties

Hexagonal boron nitride (h-BN)-based heat-spreading materials have drawn considerable attention in electronic diaphragm and packaging fields because of their high thermal conductivity and desired electrical insulation properties. However, the traditional approach to fabricate thermally conductive composites usually suffers from low thermal conductivity, and cannot meet the requirement of thermal management. In this work, novel h-BN/cellulose-nano fiber (CNF) composite films with excellent thermal conductivity in through plane and electrical insulation properties are fabricated via an innovative process, i.e., the perfusion of h-BN into porous three dimensional (3D) CNF aerogel skeleton to form the h-BN thermally conductive pathways by filling the CNF aerogel voids. When at an h-BN loading of 9.51 vol %, the thermal conductivity of h-BN/CNF aerogel perfusion composite film is 1.488 W·m−1·K−1 at through plane, an increase by 260.3%. The volume resistivity is 3.83 × 1014 Ω·cm, superior to that of synthetic polymer materials (about 109~1013 Ω·cm). Therefore, the resulting h-BN/CNF film is very promising to replace the traditional synthetic polymer materials for a broad spectrum of applications, including the field of electronics.

Research on DC dielectric properties of polyaniline nanofibers/LDPE composites

2016 ◽  
Vol 30 (1) ◽  
pp. 76-81 ◽  
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.

scholarly journals Research on the Compound Optimization Method of the Electrical and Thermal Properties of SiC/EP Composite Insulating Material

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3369
Author(s):  
Xupeng Song ◽  
Xiaofeng Xue ◽  
Wen Qi ◽  
Jin Zhang ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
Thermal Properties ◽  
Heat Conduction ◽  
Composite Materials ◽  
Breakdown Strength ◽  
Optimization Method ◽  
Nano Particles ◽  
Electrical Performance ◽  
Conduction Channel

In this paper, in order to improve the electrical and thermal properties of SiC/EP composites, the methods of compounding different crystalline SiC and micro-nano SiC particles are used to optimize them. Under different compound ratios, the thermal conductivity and breakdown voltage parameters of the composite material were investigated. It was found that for the SiC/EP composite materials of different crystal types of SiC, when the ratio of α and β silicon carbide is 1:1, the electrical performance of the composite material is the best, and the breakdown strength can be increased by more than 10% compared with the composite material filled with single crystal particles. For micro-nano compound SiC/EP composites, different total filling amounts of SiC correspond to different optimal ratios of micro/nano particles. At the optimal ratio, the introduction of nanoparticles can increase the breakdown strength of the composite material by more than 10%. Compared with the compound of different crystalline SiC, the advantage is that the introduction of a small amount of nanoparticles can play a strong role in enhancing the break-down field strength. For the filled composite materials, the thermal conductivity mainly depends on whether an effective heat conduction channel can be constructed. Through experiments and finite element simulation calculations, it is found that the filler shape and particle size have a greater impact on the thermal conductivity of the composite material, when the filler shape is rounder, the composite material can more effectively construct the heat conduction channel.

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 Modified Molecular Chain Displacement Analysis Employing Electro-Mechanical Threshold Energy Condition for Direct Current Breakdown of Low-Density Polyethylene

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2746
Author(s):  
Minhee Kim ◽  
Se-Hee Lee
Keyword(s):  
Temperature Gradient ◽  
Space Charge ◽  
Breakdown Strength ◽  
Energy Condition ◽  
Threshold Energy ◽  
Molecular Chain ◽  
Polarity Reversal ◽  
Electrical Performance ◽  
Mechanical Threshold ◽  
Polymeric Insulators

In an HVDC environment, space charge accumulated in polymeric insulators causes severe electric field distortion and degradation of breakdown strength. To analyze the breakdown characteristics, here, the space charge distribution was numerically evaluated using the bipolar charge transport (BCT) model, considering the temperature gradient inside the polymeric insulator. In particular, we proposed an electro-mechanical threshold energy condition, resulting in the modified molecular chain displacement model. The temperature gradient accelerates to reduce the breakdown strength with the polarity-reversal voltage, except during the harshest condition, when the temperature of the entire polymeric insulator was 70 °C. The energy imbalance inside the insulator caused by polarity-reversal voltage reduced the breakdown strength by 82%. Finally, this numerical analysis model can be used universally to predict the breakdown strength of polymeric insulators in various environments, and help in evaluating the electrical performance of polymeric insulators.

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