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Novel epoxy nanocomposites are fabricated by using 3D interconnected boron nitride nanosheets (BNNSs). The nanocomposites exhibit ultrahigh thermal conductivity enhancement and suppressed dielectric loss at low BNNS loading. Furthermore, the obtained nanocomposites have high electrical insulation performance, showing potential applications in high power LED, advanced packaging materials and microelectronic...
High-dielectric-constant (High-κ) nanocomposites are demonstrated to show great promise as energy storage materials. The introduction of high-κ nanomaterials into ferroelectric polymers has proven to be a promising strategy for the fabrication of high-κ nanocomposites. One dimensional large-aspect-ratio nanowires exhibit superiority in enhancing κ and energy density of polymer nanocomposites in comparison...
This work was aimed to investigate the influence of alumina (Al2O3) nanoparticle surface modification on the micro structure and dielectric properties of epoxy nanocomposites. Al2O3 nanoparticles were first modified by two modifiers [i.e., γ-aminopropyl-tri-ethoxysilane (APS), hyperbranched aromatic polyamide (HBP)] and then their epoxy nanocomposites were fabricated. The nanocomposites with unmodified...
Polystyrene@BaTiO3 (PS@BT) nanomposites with high dielectric constant and low dielectric loss were prepared by using the grafting to strategy. In this method, PS macromolecules with different molecular weights were first prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization and then the PS macromolecules were grafted onto the surfaces of BT nanoparticles by using a so-called...
Nanocomposite dielectrics with high permittivity and low dielectric loss have potential applications in energy storage devices. In this work, the unique core-double-shell barium titanate (BaTiO3) nanocomposite dielectrics were successfully prepared by an in situ polymerization technique, in which BaTiO3 nanoparticles were used as the core, and the two shells are hyperbranched aromatic polyamide (HBP)...
Two groups of fresh full size stator bars of an 18 kV/180 MW generator were subjected to accelerated thermomechanical and electrical-thermal combined stress aging respectively to investigate the deterioration of groundwall insulation. The dissipation factor measurement was performed during the thermomechanical stress aging together with tap testing and dimension measurement. In addition, the dissipation...
Novel poly(methyl methacrylate) (PMMA) nanocomposites with high dielectric constant and low loss were successfully fabricated by using sandwich-structured polyaniline-graphene-polyaniline (rPANI-GS-rPANI) hybrids sheets as fillers. The hybrid sheets were obtained by two steps: aniline was first in situ polymerized on both surfaces of graphene oxide (GO) sheets and then the PANI-GS-PANI sheets were...
Graphene, a two-dimensional monolayer of carbon atoms with conjugated honeycomb structure, has received broad interest owing to its unique physical properties such as high electrical conductivity, excellent mechanical strength, and large surface area. One promising route to harnessing these properties for applications is to improve dielectric properties of polymer by adding graphene sheets at low...
The incorporation of high-dielectric-constant ceramic nano-filler into polymer matrix is an important approach to prepare polymer composites with excellent dielectric performance. However, the easy aggregation of inorganic nano-filler generally not only results in poor film quality and inhomogeneities, but also affects the dielectric performance. Herein, a novel route to prepare core-shell structured...
Graphene oxide nanosheets (GOn)/PVDF nanocomposites with various GOn contents were fabricated using solution mixing followed by hot press molding and solution casting respectively. The dielectric behavior of those nanocomposites was determined over a wide frequency range from 102 to 107 Hz. The percolation phenomenon was observed in GOn/PVDF nanocomposites prepared by hot press molding method instead...
Barium titanate@ poly (methyl methacrylate) (BT@PMMA) nanocomposites were prepared via in situ atom transfer radical polymerization (ATRP). It was observed that the BT nanoparticles were coated with PMMA and excellently dispersed in the polymer matrix. Compared with the BT/PMMA nanocomposites prepared by the traditional solution blending, BT@PMMA nanocomposites show higher thermal conductivity and...
Graphene and graphene oxide are increasingly attracting worldwide attention from academia and industry. The physical properties of graphene have been documented recently, and we have known that the sea of electrons in the two-dimensional, single layer of sp2 hybridized carbon atoms causes graphene to act both as electrical and thermal conductors. In contrast, graphene oxide, an oxidized graphene sheet...
High permittivity polymer-based composites have attracted increasing attention because of their inherent advantages of being easy to process, flexible and light weight in electronic and electrical industry. However, the permittivity of common polymer is very low (<10). Adding conductive fillers provides a promising route to significantly increase the permittivity of a polymer with a low loading...
In this work, by using a hyperbranched aromatic polyamide grafted boron nitride nanoplatelets (BNNP-HBP), epoxy nanocomposites with high thermal conductivity and high breakdown strength are successfully prepared. All the composite samples with less than 40 wt% BNNP-HBP show increased thermal conductivity and breakdown strength when compared the pure epoxy resin and the composites with as received...
Forty percent of transmission and distribution power grids are composed of underground cables in Shanghai, a city with abundance surface water. The cables are subjected to a variety of stress factors due to the complicated underground environment and the ageing process is accelerated consequently. Lots of cables have been in service for over 20 years and there tends to be frequent accidents due to...
Poly(methyl methacrylate) (PMMA) nanocomposites containing BaTiO3 were prepared by in situ atom transfer radical polymerization (ATRP). The nanocomposites show significantly increased dielectric constant when compared with the pure PMMA, whereas the dielectric loss of the nanocomposite is kept at the same low level as that of the pure PMMA. For example, at 1000 Hz, the dielectric constant increases...
Dielectric polymer composites with high thermal conductivity and high breakdown strength have wide applications in electronic devices and electrical equipment. In this study, poly (phenylene sulfide) [PPS] and boron nitride (BN) were selected for preparing high thermal conductivity composites for high temperature insulation application. The composites were prepared by melt compounding to contain 0–40...
The paper evaluated the water tree resistance of cross-linked polyethylene (XLPE) by using an elastomer modified with polar molecules. Samples containing maleic anhydride grafted poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-g-Ma) have been prepared by melt compounding and subsequent compression molding, respectively. Accelerated water tree aging of the samples was carried out under the combined...
The development of devices for electric stress control includes several significant challenges for polymer composite dielectrics, including the need for high permittivity, high mechanical strength, high thermal conductivity, good dielectric strength, and good ductility. However, the conventional methods to increase the permittivity of a polymer suffer from very low mechanical and dielectric strength...
This paper evaluated the influences of silica nanoparticles on the dielectric properties, mechanical performances and glass transformation behaviors of epoxy resin by analyzing the temperature dependence of dc conduction and dielectric loss, impact test results and dynamic mechanical data, respectively. The particular attention was given to the correlation between the glass transformation behaviors,...
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