scholarly journals Effect of Environmental Temperature on the Insulating Performance of Epoxy/MgO Nanocomposites

2020 ◽  
Vol 10 (20) ◽  
pp. 7018
Author(s):  
Guanghui Ge ◽  
Yongzhe Tang ◽  
Yuxia Li ◽  
Liangsong Huang
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Thermal Properties ◽  
Dielectric Loss ◽  
Epoxy Resin ◽  
Environmental Temperature ◽  
Breakdown Strength ◽  
Volume Resistivity ◽  
Mgo Nanoparticles ◽  
Pure Epoxy

This article reports on the development of nano-MgO/epoxy resin composites with various mass ratios via a solution blending method. The influence of MgO nanofillers on the thermal properties and the effect of environmental temperature on the insulating properties of the composite material were analyzed. The results show that the thermal conductivity of the composites increased with an increasing MgO nanofiller content. Compared with the pure epoxy resin, the thermal conductivity increased by 75% when the content of MgO nanoparticles was 7%. The volume resistivity first increased and then decreased with an increasing doping concentration. The volume resistivity increased by 26.8% in comparison with the pure epoxy resin when the content of MgO nanoparticles was 1%, while its dielectric constant and dielectric loss increased with temperature. In addition, the dielectric constant increased and the dielectric loss first decreased and then increased with an increasing MgO nanoparticle content. Moreover, the MgO composites changed from a glassy to a rubbery state, and the breakdown strength was significantly reduced with an increased temperature. When the temperature was higher than the glass transition temperature, the breakdown strength decreased by 51.3% compared with the maximum breakdown strength at 20 °C. As the content of MgO nanoparticles increased, the breakdown strength of the composite first increased and then decreased. The highest breakdown strength was achieved when the content of MgO nanoparticles was 1%, which was 11.1% higher than that of the pure epoxy resin. It was concluded that the MgO nanofillers can significantly improve the thermal properties of epoxy composites and their insulation performance at high temperatures.

Influence of the Morphology of Alumina Filler on Electrical and Thermal Properties of Epoxy Resin Composites

2018 ◽  
Vol 922 ◽  
pp. 163-168 ◽  
Author(s):  
Jia Wei Ma ◽  
Nai Kui Gao ◽  
Teng Yue Ren ◽  
Ze Hua Pan ◽  
Hai Yun Jin
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Epoxy Resin ◽  
Room Temperature ◽  
Volume Resistivity ◽  
Resin Composites ◽  
Casting Method ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Epoxy Resin Composites

Epoxy resin composites filled with alumina (Al2O3) particles of different morphology and content were fabricated by vacuum casting method. Electric and thermal properties of the composites were tested at room temperature to investigate the influence of Al2O3 morphology on epoxy resin composites. Electrical tests demonstrated that, volume resistivity of epoxy resin composites filled with spherical Al2O3 was bigger than with spherical-like Al2O3, relative permittivity and dielectric loss of epoxy resin composites increased with increasing of Al2O3 content, the effect on dielectric properties of spherical-like Al2O3, which had larger specific surface areas, was larger than spherical Al2O3 for the same content of filler. Thermal conductivity tests proved that, at the same content, thermal conductivity of epoxy resin composites filled with spherical-like Al2O3 was higher than with spherical Al2O3. According to the Agari model, spherical-like Al2O3 particles were easier to form conducting pathways in epoxy resin composites than spherical Al2O3 particles, considering their matte edges.

Enhanced dielectric properties and thermostability in polyimide composites with core-shell structured polyimide@BaTiO3 nanoparticles

2021 ◽  
pp. 095400832199352
Author(s):  
Wei Deng ◽  
Guanguan Ren ◽  
Wenqi Wang ◽  
Weiwei Cui ◽  
Wenjun Luo
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Energy Density ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Dielectric Materials ◽  
High Energy ◽  
Amic Acid ◽  
High Energy Density ◽  
Core Shell

Polymer composites with high dielectric constant and thermal stability have shown great potential applications in the fields relating to the energy storage. Herein, core-shell structured polyimide@BaTiO3 (PI@BT) nanoparticles were fabricated via in-situ polymerization of poly(amic acid) (PAA) and the following thermal imidization, then utilized as fillers to prepare PI composites. Increased dielectric constant with suppressed dielectric loss, and enhanced energy density as well as heat resistance were simultaneously realized due to the presence of PI shell between BT nanoparticles and PI matrix. The dielectric constant of PI@BT/PI composites with 55 wt% fillers increased to 15.0 at 100 Hz, while the dielectric loss kept at low value of 0.0034, companied by a high energy density of 1.32 J·cm−3, which was 2.09 times higher than the pristine PI. Moreover, the temperature at 10 wt% weight loss reached 619°C, demonstrating the excellent thermostability of PI@BT/PI composites. In addition, PI@BT/PI composites exhibited improved breakdown strength and toughness as compared with the BT/PI composites due to the well dispersion of PI@BT nanofillers and the improved interfacial interactions between nanofillers and polymer matrix. These results provide useful information for the structural design of high-temperature dielectric materials.

scholarly journals Preparation and characterization of novel naphthyl epoxy resin containing 4-fluorobenzoyl side chains for low-k dielectrics application

RSC Advances ◽  
2017 ◽  
Vol 7 (85) ◽  
pp. 53970-53976 ◽  
Author(s):  
Tianyi Na ◽  
Hao Jiang ◽  
Liang Zhao ◽  
Chengji Zhao
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Side Chains ◽  
The Novel ◽  
Lower Dielectric Constant ◽  
Low K

The novel naphthyl epoxy resin was synthesized and cured with MeHHPA. It showed significantly lower dielectric constant and dielectric loss than other commercial epoxy resins due to the introduction of fluorine on the side chains.

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

Materials ◽  
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.

Thermomechanical properties of silica–epoxy nanocomposite modified by hyperbranched polyester: A molecular dynamics simulation

2021 ◽  
pp. 095400832110323
Author(s):  
Jianwen Zhang ◽  
Dongwei Wang ◽  
Lujia Wang ◽  
Wanwan Zuo ◽  
Xiaohua Ma ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Glass Transition ◽  
Epoxy Resin ◽  
Silica Surface ◽  
Thermomechanical Properties ◽  
Dynamics Simulation ◽  
Hyperbranched Polyester ◽  
Pure Epoxy ◽  
Epoxy Nanocomposite

In this article, pure epoxy resin and silica–epoxy nanocomposite models were established to investigate the effects of hyperbranched polyester on microstructure and thermomechanical properties of epoxy resin through molecular dynamics simulation. Results revealed that the composite of silica can improve the thermomechanical properties of nanocomposites, including the glass transition temperature, thermal conductivity, and elastic modulus. Moreover, the thermomechanical properties were further enhanced through chemical modification on the silica surface, where the effectiveness was the best through grafting hyperbranched polyester on the silica surface. Compared with pure epoxy resin, the glass transition temperature of silica–epoxy composite modified by silica grafted with hyperbranched polyester increased by 38 K. The thermal conductivity increased with the increase of temperature and thermal conductivity at room temperature increased to 0.4171 W/(m·K)−1 with an increase ratio of 94.3%. Young’s modulus, volume modulus, and shear modulus all fluctuated as temperature rise with a down overall trend. They increased by 44.68%, 29.52%, and 36.65%, respectively, when compared with pure epoxy resin. At the same time, the thermomechanical properties were closely related to the microstructure such as fractional free volume (FFV), mean square displacement (MSD), and binding energy. Silica surface modification by grafting hyperbranched polyester reduced the FFV value and MSD value most and strengthened the combination of silica and epoxy resin matrix the best, resulting in the best thermomechanical properties.

scholarly journals Materials with low dielectric constant and loss and good thermal properties prepared by introducing perfluorononenyl pendant groups onto poly(ether ether ketone)

RSC Advances ◽  
2018 ◽  
Vol 8 (14) ◽  
pp. 7753-7760 ◽  
Author(s):  
Handong Sun ◽  
Yunxia Lv ◽  
Chongyang Zhang ◽  
Xiaodan Zuo ◽  
Mengzhu Li ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Thermal Properties ◽  
Dielectric Loss ◽  
Polymer Chain ◽  
Low Dielectric Constant ◽  
Low Dielectric ◽  
Dielectric Constant And Loss ◽  
Ether Ether Ketone ◽  
Poly Ether Ether Ketone ◽  
Ether Ketone

Introducing long carbon–fluorine bonds into the polymer chain produced comb-shaped PEEK possessing a low dielectric constant (2.73) and low dielectric loss (3.00 × 10−3).

scholarly journals The Effects of TDI on Selected Properties of Ester Epoxy Alkyd Varnish

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Nguyen Trung Thanh
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Heat Resistance ◽  
Epoxy Resin ◽  
Breakdown Voltage ◽  
Toluene Diisocyanate

This article presents the effects of toluene diisocyanate (TDI) on electrical properties of ester epoxy alkyd varnish. Through testing on breakdown voltage, dielectric constant, block resistivity, Tang (Tg) dielectric loss, the electrical properties of varnish were investigated. When TDI amount increased from to 4 - 10 (w/100w of epoxy resin), the breakdown voltage increased from 21.78 to 65.69 KV/mm. With TDI of 8 - 10 w/w, the dielectric constant was the best, about 2.78 - 3.02. With TDI of 8 w/w, the block resistivity was 6.8.1014 W.cm and Tg dielectric loss was 0.0069. The article also presents the effect of TDI on solvent- and heat resistance of the varnish.

scholarly journals The Dielectric Properties and Thermal Conductivities of Epoxy Composites Reinforced by Titanium Dioxide

2021 ◽  
Author(s):  
Yuan Jia ◽  
Juxiang Yang ◽  
Weijie Dong ◽  
Beibei Li ◽  
Zhen Liu
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Titanium Dioxide ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Hydrothermal Process ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Ep Matrix ◽  
Thermal Conductivities

Abstract To improve the dielectric properties and thermal conductivities of epoxy resins (EP), titanium dioxide superfine powders with microspheres structure (S-TiO2) were prepared via a hydrothermal process based on the sodium dodecyl benzene sulfonate and hydroxyl silicate. The different content of S-TiO2 was then employed as modifiers to add into EP resin to prepare the S-TiO2/EP composites. The structure and morphology of the prepared S-TiO2 was observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and influences of different addition of S-TiO2 on the thermal conductivity of S-TiO2/EP composites are researched, while their dielectric constant and dielectric loss are also studied. The results suggested that the reasonable content of S-TiO2 can endow the S-TiO2/EP composites with higher dielectric constant without excessive increase their dielectric loss even under the high frequency. Furthermore, the thermal conductivity of S-TiO2/EP are also be improved, which can be attributed to the good thermal conductivity of S-TiO2 itself and the thermal conductivity path formed by S-TiO2 inside the EP matrix.

Fabrication of PMIA/fBN Dielectric Composite with Enhanced Breakdown Strength and Thermal Conductivity

2019 ◽  
Vol 960 ◽  
pp. 256-262
Author(s):  
Guang Yu Duan ◽  
Zu Ming Hu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
High Temperature ◽  
Dielectric Property ◽  
Dielectric Loss ◽  
Breakdown Strength ◽  
Dielectric Composite ◽  
Novel Method ◽  
Thermal Conductivities

A high-temperature poly (m-phenyleneisophthalamide) (PMIA) dielectric composite was successfully manufactured with functionalized BN (fBN) fillers. Due to effective modification by KH-550, fBN particles evenly dispersed in PMIA matrix. The dielectric property, breakdown strength and thermal conductivity of PMIA/fBN dielectric composite were researched. The consequences indicate that fBN fillers can not only decrease the dielectric loss but also enhance the breakdown strength of PMIA/fBN dielectric composites. Furthermore, owing to the generated heat transfer pathways by fBN particles, the thermal conductivities improved from 0.23 W·m-1·K-1 of fBN-0 to 0.86 W·m-1·K-1 of fBN-30, demonstrating a significant improvement. These results present a novel method for fabricating high-temperature PMIA/fBN dielectric composites with improved breakdown strength and thermal conductivity.

scholarly journals Effect of Al2O3 with Different Nanostructures on the Insulating Properties of Epoxy-Based Composites

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4235
Author(s):  
Yongzhe Tang ◽  
Guanghui Ge ◽  
Yuxia Li ◽  
Liangsong Huang
Keyword(s):  
Thermal Conductivity ◽  
Power Systems ◽  
Mass Fraction ◽  
Breakdown Strength ◽  
Filler Particle ◽  
Volume Resistivity ◽  
Dielectric Constants ◽  
Filler Particle Size ◽  
Mass Fractions ◽  
Insulating Properties

High thermal conductivity insulating dielectrics with good electrical properties have received widespread attention due to the continuous development of power systems and power electronic technologies. In this paper, the effects of differently structured nano alumina fillers on the thermal conductivity and insulating properties of polymer-based composites were studied. It was found that all three types of Al2O3 nano-fillers enhanced the thermal conductivity of the composites, and the thermal conductivity increased more dramatically with increasing filler particle size. It is worth noting that Al2O3 nanowires (NWs) exhibited the most significant improvement in thermal conductivity. The volume resistivity of the composites first increased and then decreased with increasing mass fraction of fillers, and Al2O3 nanoplates (NPLs) showed the most significant improvement in the insulation performance of the composites. The dielectric constants of the composites increased with increasing mass fraction of fillers, while the dielectric losses first decreased and then increased with the same trend, yet the mass fractions of fillers for the three materials were different when the dielectric loss reached a minimum. In addition, all three types of filler increased the AC breakdown strength of the composites, but Al2O3-NPLs showed the most significant improvement on the breakdown performance of the composites.

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