scholarly journals Synergistic Enhancement of Thermal Conductivity and Dielectric Properties in Al2O3/BaTiO3/PP Composites

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1536 ◽  
Author(s):  
Junlong Yao ◽  
Li Hu ◽  
Min Zhou ◽  
Feng You ◽  
Xueliang Jiang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Properties ◽  
Polymer Composites ◽  
Volume Fraction ◽  
Dielectric Constants ◽  
High Thermal Conductivity ◽  
Al2o3 Nanoparticles ◽  
Pp Composites ◽  
Ceramic Fillers ◽  
High Dielectric

Multifunctional polymer composites with both high dielectric constants and high thermal conductivity are urgently needed by high-temperature electronic devices and modern microelectromechanical systems. However, high heat-conduction capability or dielectric properties of polymer composites all depend on high-content loading of different functional thermal-conductive or high-dielectric ceramic fillers (every filler volume fraction ≥ 50%, i.e., ffiller ≥ 50%), and an overload of various fillers (fthermal-conductive filler + fhigh-dielectric filler > 50%) will decrease the processability and mechanical properties of the composite. Herein, series of alumina/barium titanate/polypropylene (Al2O3/BT/PP) composites with high dielectric- and high thermal-conductivity properties are prepared with no more than 50% volume fraction of total ceramic fillers loading, i.e., ffillers ≤ 50%. Results showed the thermal conductivity of the Al2O3/BT/PP composite is up to 0.90 W/m·K with only 10% thermal-conductive Al2O3 filler, which is 4.5 times higher than the corresponding Al2O3/PP composites. Moreover, higher dielectric strength (Eb) is also found at the same loading, which is 1.6 times higher than PP, and the Al2O3/BT/PP composite also exhibited high dielectric constant ( ε r = 18 at 1000 Hz) and low dielectric loss (tan δ ≤ 0.030). These excellent performances originate from the synergistic mechanism between BaTiO3 macroparticles and Al2O3 nanoparticles.

Preparation, Morphology and Dielectric Properties of Polyamide-6/Poly(Vinylidene Fluoride) Blends

2012 ◽  
Vol 496 ◽  
pp. 263-267
Author(s):  
Rui Li ◽  
Jian Zhong Pei ◽  
Yan Wei Li ◽  
Xin Shi ◽  
Qun Le Du
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Flexible Electronics ◽  
High Dielectric Constant ◽  
Vinylidene Fluoride ◽  
Volume Fraction ◽  
Polyamide 6 ◽  
Dielectric Constants ◽  
Poly Vinylidene Fluoride ◽  
High Dielectric

A novel all-polymeric material with high dielectric constant (k) has been developed by blending poly (vinylidene fluoride) (PVDF) with polyamide-6 (PA6). The dependence of the dielectric properties on frequency and polymer volume fraction was investigated. When the volume fraction of PA6 is 20%, the dielectric property is better than others. The SEM investigations suggest that the enhanced dielectric behavior originates from significant interfacial interactions of polymer-polymer. The XRD demonstrate that the PA6 and PVDF affect the crystalline behavior of each component. Furthermore, the stable dielectric constants of the blends could be tuned by adjusting the content of the polymers. The created high-k all-polymeric blends represent a novel type of material that are simple technology and easy to process, and is of relatively high dielectric constant, applications as flexible electronics.

scholarly journals Synergistic Effects of Boron Nitride (BN) Nanosheets and Silver (Ag) Nanoparticles on Thermal Conductivity and Electrical Properties of Epoxy Nanocomposites

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 426 ◽  
Author(s):  
Yunjian Wu ◽  
Xiaoxing Zhang ◽  
Ankit Negi ◽  
Jixiong He ◽  
Guoxiong Hu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Properties ◽  
Boron Nitride ◽  
Polymer Composites ◽  
Synergistic Effects ◽  
High Thermal Conductivity ◽  
Epoxy Nanocomposites ◽  
Transfer Path ◽  
Low Dielectric ◽  
Low Permittivity

Polymer composites, with both high thermal conductivity and high electrical insulation strength, are desirable for power equipment and electronic devices, to sustain increasingly high power density and heat flux. However, conventional methods to synthesize polymer composites with high thermal conductivity often degrade their insulation strength, or cause a significant increase in dielectric properties. In this work, we demonstrate epoxy nanocomposites embedded with silver nanoparticles (AgNPs), and modified boron nitride nanosheets (BNNSs), which have high thermal conductivity, high insulation strength, low permittivity, and low dielectric loss. Compared with neat epoxy, the composite with 25 vol% of binary nanofillers has a significant enhancement (~10x) in thermal conductivity, which is twice of that filled with BNNSs only (~5x), owing to the continuous heat transfer path among BNNSs enabled by AgNPs. An increase in the breakdown voltage is observed, which is attributed to BNNSs-restricted formation of AgNPs conducting channels that result in a lengthening of the breakdown path. Moreover, the effects of nanofillers on dielectric properties, and thermal simulated current of nanocomposites, are discussed.

Characterization of Nanocomposites Incorporating PZT Nanowires for Enhanced Energy Storage

2010 ◽  
Author(s):  
Haixiong Tang ◽  
Yirong Lin ◽  
Clark Andrews ◽  
Henry A. Sodano
Keyword(s):  
Energy Storage ◽  
Dielectric Properties ◽  
Energy Density ◽  
Aspect Ratio ◽  
Electric Field ◽  
Polymer Composites ◽  
Volume Fraction ◽  
High Energy ◽  
High Energy Density ◽  
High Dielectric

0–3 Piezoceramic polymer composites have attracted immense attention due to the flexibility afforded by the polymer matrix and the strong electromechanical coupling and high dielectric properties of the piezoceramic filler. The majority of research on these materials has focused on the effective piezoelectric properties of the piezoceramic polymer composites. However, the high dielectric strength of the polymer combined with the high permittivity of the ceramic filler make them well suited for use as high energy density capacitors and various pulsed power applications. Current work in this area has focused on the enhancement of the dielectric properties through a variation of nanoparticle composition or surface modifications to the fillers to enhance the energy density of composites. Recently, research and micromechanics modeling have shown that the filler aspect ratio plays an important role in increasing the effective dielectric properties of the composites. Therefore, unlike prior efforts, this work will focus on the effect of filler aspect ratio on the dielectric properties of the bulk nanocomposite. Nanocomposites were synthesized using lead zirconate titanate (PZT) with two different aspect ratio (nanowires, nanorods) fillers at various volume fractions dispersed in a polyvinylidene fluoride (PVDF) matrix. It was shown that the nanocomposites containing PZT nanowires (NWs) significantly increased the energy density compared to those containing lower aspect ratio PZT nanorods (NRs). The permittivity constants of composites containing PZT NWs were higher than those with PZT NRs at the same inclusion volume fraction. The experimental results also indicated that the high frequency loss tangent of nanocomposites with PZT NWs was smaller than those of PZT NRs, demonstrating the high electrical energy storage efficiency of the PZT NW composite. The PZT NW nanocomposites showed a 77.8% increase in energy density over the PZT NR nanocomposites, under an electric field of 15 kV/mm and 50% volume fraction. Because the energy density exhibits a quadratic relationship with the applied electric field, the performance enhancement through the use of NWs is even greater at higher electric fields. These results indicate that higher aspect ratio PZT nanowires shows promising potential to improve the energy density of nanocomposites, leading the development of advanced capacitors with high energy density.

scholarly journals Dielectric Properties of Wood-Polymer Composites: Effects of Frequency, Fiber Nature, Proportion, and Chemical Composition

2021 ◽  
Vol 5 (6) ◽  
pp. 141
Author(s):  
Imen Elloumi ◽  
Ahmed Koubaa ◽  
Wassim Kharrat ◽  
Chedly Bradai ◽  
Ahmed Elloumi
Keyword(s):  
Dielectric Properties ◽  
Polymer Composites ◽  
Wide Frequency Range ◽  
Dielectric Constants ◽  
Cellulose Content ◽  
Wood Fibers ◽  
Low Frequencies ◽  
Wood Polymer ◽  
Wood Polymer Composites ◽  
New Applications

The characterization of the dielectric properties of wood–polymer composites (WPCs) is essential to understand their interaction with electromagnetic fields and evaluate their potential use for new applications. Thus, dielectric spectroscopy monitored the evolution of the dielectric properties of WPCs over a wide frequency range of 1 MHz to 1 GHz. WPCs were prepared using mixtures of different proportions (40%, 50%, and 60%) of wood and bark fibers from various species, high-density polyethylene, and maleated polyethylene (3%) by a two-step process, extrusion and compression molding. Results indicated that wood fibers modify the resistivity of polyethylene at low frequencies but have no effect at microwave frequencies. Increasing the fiber content increases the composites’ dielectric properties. The fibers’ cellulose content explains the variation in the dielectric properties of composites reinforced with fibers from different wood species. Indeed, composites with high cellulose content show higher dielectric constants.

Microwave synthesis of branched silver nanowires and their use as fillers for high thermal conductivity polymer composites

2016 ◽  
Vol 27 (17) ◽  
pp. 175601 ◽  
Author(s):  
Indira Seshadri ◽  
Gibran L Esquenazi ◽  
Thomas Cardinal ◽  
Theodorian Borca-Tasciuc ◽  
Ganpati Ramanath
Keyword(s):  
Thermal Conductivity ◽  
Polymer Composites ◽  
Microwave Synthesis ◽  
Silver Nanowires ◽  
High Thermal Conductivity

New Perovskite Nanomaterials and Their Integrations into High-k Dielectrics

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000072-000077
Author(s):  
Minoru Osada ◽  
Takayoshi Sasaki
Keyword(s):  
Dielectric Properties ◽  
Room Temperature ◽  
Bottom Electrode ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Layered Perovskite ◽  
Layer By Layer ◽  
High K ◽  
High K Dielectric ◽  
High Dielectric

We report on a bottom-up manufacturing for high-k dielectric films using a novel nanomaterial, namely, a perovskite nanosheet (LaNb2O7) derived from a layered perovskite by exfoliation. Solution-based layer-by-layer assembly of perovskite nanosheets is effective for room-temperature fabrication of high-k nanocapacitors, which are directly assembled on a SrRuO3 bottom electrode with an atomically sharp interface. These nanocapacitors exhibit high dielectric constants (k > 50) for thickness down to 5 nm while eliminating problems resulting from the size effect. We also investigate dielectric properties of perovskite nanosheets with different compositions (LaNb2O7, La0.95Eu0.05Nb2O7, and Eu0.56Ta2O7) in order to study the influence of A- and B-site modifications on dielectric properties.

Microstructure and Dielectric Properties of LixTixNi1-2xO Thin Films

2008 ◽  
Vol 368-372 ◽  
pp. 1817-1819
Author(s):  
Cui Hua Zhao ◽  
Bo Ping Zhang ◽  
Yong Liu ◽  
Song Jie Li
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Spin Coating ◽  
Sol Gel ◽  
Dielectric Constants ◽  
Co Doping ◽  
Grain Sizes ◽  
Uniform Microstructure ◽  
Coating Method ◽  
High Dielectric

LixTixNi1-2xO (x =0, 10 and 20 at. %) thin films with 200 nm in thickness were deposited on Pt/Ti/SiO2/Si (100) by a sol-gel spin-coating method. All samples have a uniform microstructure. The grain sizes grew from 100 nm to 300 nm by co-doping Li and Ti. The LiTiNiO thin films consist of NiO, NiTiO3 and Li2NiO2, while the Li-free thin films consist of NiO, NiTiO3 and NiTi0.99O3. The dielectric properties of the LiTiNiO thin films improved obviously by co-doping Li and Ti, but excess Li increases the amount of Li2NiO2 phase and decreases the dielectric properties. The dielectric constants at 100 Hz for the Li0.1Ti0.1Ni0.8O and Li0.2Ti0.2Ni0.6O thin films are 506 and 388 respectively. Appropriate co-doping contents of Li and Ti are important to obtain a high dielectric property.

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