Dielectric Properties Of Polymer Composites Research Articles

Optimizing the dielectric properties of polymer composites by constructing multi-dimensional fillers

The construction of multidimensional fillers provides new ideas for the development of composite materials. In this study, one-dimensional (La0.5Nb0.5)xTi1-xO2 ceramic nanorods (x-LNTO NRs) and 1-LNTO ceramic materials with three-dimensional fiber structure network (3D-1-LNTO) were prepared by electrospinning. These materials were used as fillers to prepare x-LNTO NRs/PVDF composites and 3D-1-LNTO/PVDF composites. Compared with the 1-LNTO NPs/PVDF composites, the 1-LNTO NRs/PVDF composites showed better dielectric properties, with a dielectric constant of 40 and a dielectric loss of 0.12 at a fill content of 60 wt%. The 3D-1-LNTO/PVDF composites achieved a high dielectric constant at a low filler content, the composite achieved a dielectric constant of 25 at a fill content of only 10 wt%, which is 2.5 times higher than that of pure PVDF. Compared with x-LNTO NRs, 3D-1-LNTO is more obvious for improving the dielectric properties of composites. The construction of continuous fiber network is the main reason for the enhancement of dielectric constant, and this study provides a new experimental idea for the construction of multi-dimensional high dielectric fillers.

Notably enhanced dielectric response with low loss in PVDF composites filled with RuO2–BaTiO3 hybrid particles

This study delineates the process of fabricating and the results of investigating the dielectric properties of hybrid particles created through the integration of Poly(vinylidene fluoride) (PVDF) filled with RuO2 coated on BaTiO3 nanoparticles (nBT), designated as RuO2–nBT. These hybrid particles were successfully synthesized employing a simple and cost–effective solid–state reaction method. The inclusion of RuO2–nBT in the PVDF matrix engendered a notable enhancement in its dielectric properties. Notably, a RuO2–nBT fraction of 0.5 manifested a dielectric constant (ε′) of 107.4 and a dielectric loss tangent (tanδ) value of 0.062 at 30 °C and 1 kHz. These findings signify the effective role of interfacial polarization occurring between the PVDF matrix and the RuO2–nBT hybrid particles, leading to a marked improvement in dielectric attributes. Moreover, the observed low tanδ value indicates the elimination of conductive pathways, an inhibitory effect attributed to the incorporation of RuO2–nBT hybrid particles. This study underscores the promising potential of RuO2–nBT hybrid particles in fine–tuning and augmenting the dielectric properties of polymer composites, particularly in scenarios necessitating low tanδ and high ε′ values.

Enhanced dielectric performance of PVDF composites doped with MnO2@carbon particles

Herein, a method is proposed for preparing MnO2@carbon core–shell particles and MnO2@carbon/polyvinylidene fluoride (PVDF) composite films. The effect of MnO2@carbon core–shell particles on the dielectric properties of polymer composites was investigated. Furthermore, a comprehensive dielectric property test was conducted on the composite films. The results reveal that with the addition of MnO2@carbon core–shell particles, the dielectric properties of the composite films also improved. The dielectric constant of the 10 wt% MnO2@carbon composite is 24.2 at 100 Hz, which is 3 times that of PVDF (7.68). Currently, the energy storage density of the composite film is 4.95 J cm−3 at ∼2300 kV cm−1. The addition of MnO2@carbon core–shell particles effectively improves the energy storage density of PVDF. Based on this result, the influence of the carbon shell on the dielectric properties of the composite thin films is analysed and discussed. The significant improvement in dielectric properties is mainly due to the increased interfacial polarisation induced by the carbon shell. These characteristics of PVDF/MnO2@carbon composites indicate that the proposed method is a practical pathway to developing high-performance composites.

Enhanced Dielectric Properties of Polymer Composites with Polar Fe2TiO5 and Non-polar Diamond Nanofillers

Enhanced Dielectric Properties of Polymer Composites with Polar Fe2TiO5 and Non-polar Diamond Nanofillers

Ti3C2Tx MXene-Ag/silicone rubber composites with enhanced dielectric properties and improved mechanical properties

Conductive filler/polymer composites were widely used in dielectric devices, but high dielectric constant was accompanied by high loss tangent. Incorporating highly conductive fillers into silicone rubber (SR) matrix may be a feasible way, since the loss tangent of SR is extremely low. In this paper, to improve the dielectric properties of polymer composites, SR composites were fabricated with Ag decorated Ti3C2Tx MXene (Ti3C2Tx MXene-Ag) as the fillers. The thermal stabilities, dielectric and mechanical behaviors of the Ti3C2Tx MXene-Ag/SR composites were investigated. Compared with Ti3C2Tx MXene/SR composites, Ti3C2Tx MXene-Ag/SR composites exhibit higher dielectric constants, due to the deposition of Ag particles on the surfaces of Ti3C2Tx MXene nanosheets. The dielectric constant of Ti3C2Tx MXene-3.2Ag/SR composites is 7.29 (17.8% higher than MXene/SR composite and 162% higher than SR), and the loss tangent is as low as 0.00114 at 1 kHz. The enhanced interfacial polarization and micro-capacitor model can be used to explain the improved dielectric properties of the composites. Furthermore, the prepared SR composites have excellent mechanical properties, with a tensile stress of 554 kPa and an elongation at break of 257%. This work illustrates a method to obtain polymer-based composites with high dielectric and mechanical performances, which can be used as dielectric elastomers in actuators, sensors, biomedicine, energy collector and so on.

Polystyrene-Modulated Polypyrrole to Achieve Controllable Electromagnetic-Wave Absorption with Enhanced Environmental Stability.

The moderation of the dielectric properties of polymer composites and their environmental stability need to be considered comprehensively in the design of microwave-absorbing materials. In this work, polypyrrole/polystyrene (PPy/PS) composited particles were synthesized through a facile in situ bulk polymerization procedure. The PS component can be modulated conveniently by controlling the polymerization time. FTIR and Raman analyses disclosed that the PS component was immobilized in PPy via covalent bonds. The electromagnetic characterization results indicated that the dielectric properties and, thus, the microwave absorption could be controlled when the styrene polymerization was prolonged from 6 h (PPy-6) to 19 h (PPy-19). The composite PPy-19 displayed an optimal reflection loss of −51.7 dB with a matching thickness of 3.16 mm, and the effective absorption bandwidth (EAB) even reached 5.8 GHz at 2.4 mm. The PS component endowed PPy/PS composites with more robust environmental stability than homogeneous PPy. After being exposed to air for 365 days and hydrothermally treated at 100 °C for 12 h, PPy-19 still exhibited a reflection loss superior to −20 dB. The present work provides a new insight into the adjustment of the electromagnetic properties of PPy composites to fabricate high-performance microwave absorbers with superior environmental stability.

Thermophysical and Dielectric Properties of Polymer Composites Filled with Hexagonal Boron Nitride

Thermophysical and Dielectric Properties of Polymer Composites Filled with Hexagonal Boron Nitride

Preparation and application of dielectric polymers with high permittivity and low energy loss: A mini review

AbstractThis article reviews the preparation strategies of dielectric polymers with high permittivity and low energy loss, as well as their applications in the field of energy storage and intelligent sensors. We discuss the dependence of dielectric properties of polymer composites on different types of dielectric polarizations, including interfacial polarization, orientational polarization, ionic polarization, and electronic polarization, as well as the improvement of dielectric properties by synergetic effects of multiple polarizations. Due to the difficulties of achieving both high dielectric polarization (hence high permittivity) and low dielectric loss, we focus on the energy loss mechanism of different polarization types and issues in the preparation process. We also discuss current applications and future prospects of dielectric polymers in the field.

Materials Innovations in 2D-filler Reinforced Dielectric Polymer Composites

Polymer dielectric possess advantages of mechanical flexibility, low temperature processing, and cost. However, for practical applications dielectric constant of polymers is not high enough. To raise the dielectric constant, polymers are often composited with fillers of various morphologies (one-dimensional, two-dimensional, three-dimensional) and types (inorganic, organic, carbon, conductive, non-conductive). Recently discovered two-dimensional (2D) materials including graphene, transition metal dichalcogenides, MXenes, ferroelectric ceramics, etc. have been discovered. These materials have excellent electrical, mechanical, thermal properties and high specific surface area, which makes these ideal materials to reinforce the properties of polymers, especially dielectric properties. Here, in this review we summarize the latest developments regarding the use of 2D fillers to improve the dielectric properties of polymer composites. We have systematically discussed synthesis of 2D materials, processing of their 2D filler/polymer composites, theoretical background of dielectric properties of these composites, and literature summary of the dielectric properties of polymer composites with various type of 2D fillers.

Теплофизические и диэлектрические свойства полимерных композиций, наполненных гексагональным нитридом бора

Thermophysical and dielectric properties of polymer composites based on linear low density polyethylene (LLDPE) and poly(lactic acid) (PLA) filled with hexagonal boron nitride (hBN) have been studied. It is found that all developed composites possess dielectric properties and enhancement thermal conductivity compared with neat polymer matrices. Unlike carbonaceous fillers (carbon black, graphite, graphene, carbon nanotubes), hBN is a good insulator and therefore is more applicable as a filler for heat-releasing materials with purely white appearance. At the same time, both LLDPE/hBN and PLA/hBN composites at 40 wt% filler content possess comparable thermal conductivity about 0.7 W×m-1×K-1, which is almost 95% and 250% higher than those for the neat LLDPE and PLA, respectively.

Effect of shape of inorganic particles on dielectric properties of polymer composites with high energy density

The formation of two-phase composite materials by adding inorganic ceramic particles in the organic matrix is a hot and difficult point in the current study of high energy storage density. The electrostatic energy storage characteristics of the material are determined by its internal electric field distribution. For pure polymer materials, the internal electric field is uniformly distributed in a uniform external electric field environment, but when the inorganic particles are filled to form a composite material, the local electric field of the material will be distorted, which will affect the dielectric properties of the composite material. In this paper, the electric response properties of particles with different shape, including sphere, fiber and disk and its special arrangement has been systematically studied. The results show that both the shape and the spatial arrangement of the particles in the polymer matrix affect the local distribution of electric field. For spherical particles, there will exist be field concentration up and below the particle. For fibers, the field caused by the terminal surface bound charge should not be neglected when the aspect ratio is not large enough. At last, three three-dimensional simulation models of composites with spherical, fiber and disk particles have been established. It is indicated that composites with fiber particle possess the highest effective permittivity, while the disk particle is the lowest under the same concentration. The investigation of this paper is of great significance to understand the microscopic mechanism of energy storage.

Largely enhanced dielectric properties of polymer composites with HfO2 nanoparticles for high-temperature film capacitors

Polymer dielectrics are preferred materials for high-energy-density capacitive energy storage. In particular, high-temperature dielectrics that can withstand harsh conditions, e.g., ≥150 °C, is of crucial importance for advanced electronics and electrical power systems. Herein, high-temperature dielectric polymer composites composed of polyetherimide (PEI) matrix and hafnium oxide (HfO2) nanoparticles are presented. It is found that the incorporation of HfO2 with a moderate dielectric constant and a wide bandgap improves the dielectric constant and simultaneously reduces the high-field leakage current density of the PEI nanocomposites. As a result, the PEI/HfO2 composites exhibit superior energy storage performance to the current high-temperature engineering polymers at elevated temperatures. Specifically, the nanocomposite with 3 vol% HfO2 displays a discharged energy density of 2.82 J/cm3 at 150 °C, which is 77% higher than neat PEI. This work demonstrates the effectiveness of incorporation of the nanofiller with a medium dielectric constant into the polymer on the improvement of high-temperature capacitive properties of the polymer composites.

High Dielectric Constant and Low Percolation Threshold in Poly(vinylidene fluoride) Composite Films Containing Mechanochemically Synthesized BaSnF4 Nanowires

We prepared BaSnF4 nanowires (NWs) with a high dielectric constant using a simple high-energy ball-milling method and investigated the dielectric properties of polymer composites containing inorganic fluoride fillers. We employed various techniques, such as powder X-ray diffraction, scanning and transmission electron microscopy, and elemental mapping analysis using energy-dispersive X-ray spectroscopy, and we showed that the morphology of BaSnF4 changed from microparticles consisting of aggregated flakes to NWs as applied kinetic energy increased. A comparison of composite films containing two fillers confirmed that the dielectric constant and AC conductivity of BaSnF4 NWs at 30 vol % were two to three times higher than those of aggregated nanoparticles. Even though the breakdown strength was low at a high volume fraction, these results indicate that BaSnF4 NWs are extremely promising materials for the development of high-κ nanocomposites for various dielectric applications.

Prediction on effective permittivity of 0–3 connectivity particle/polymer composites at low concentration with finite element method

For practical application, studying the mechanism governing the macroscopic dielectric properties of polymer composites at low concentration is of great significance. A three-dimensional (3D) representative model with randomly dispersed grains in polymer matrix has been established and calculation results of effective permittivity of BT/PVDF composites with finite element method (FEM) show good consistency with experimental measurements, which demonstrate that the distribution of electric field in ceramic particles/polymer composites at low concentration can be approximated by the electrostatic field. Furthermore, the relationship between the internal electric field and dielectric properties of composites has been established. The effect of grain size in submicron and its dielectric constant to the effective permittivity of composites are fully investigated. The former shows of negligible significance compared with the evident effect of volume fraction, while the latter presents saturation as increasing the permittivity ratio between ceramic particle and polymer.

Composite material with high dielectric constant and low dielectric loss obtained through grafting of cyano groups in imidazolium ionic liquids

A strong polar cyano group was introduced to increase the interfacial polarization between filler and matrix, thereby improving the dielectric properties of polymer composites. 3-Cyanomethyl-1-vinyl imidazolium bromide (CMVImBr) ionic liquid was first synthesized, copolymerized with divinylbenzene on the surface of carbon nanotubes (CNTs) to form a core–shell structured hybrid, and then compounded with epoxy to prepare a filler-well-dispersed composite with high dielectric constant. The dielectric constant of the composites reached 139 at 1 kHz when the filler content was 20%, and the dielectric loss was only 0.088. The cyano groups and ionic bonds from CMVImBr played a significant role in increasing the dielectric constant owing to interfacial polarization. Moreover, the crosslinked polymer shells decreased the dielectric loss and served as electrical barriers between CNTs, which are desirable properties for electronic devices.

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

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 ( = 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.

Investigation of dielectric properties of polymer composites with kaolin

Thermostable nanocomposites based on interpenetrating polymer network kaolin/cyanate ester (BADCy), derived from kaolin, bisphenol A dicyanate, and doped by 1–5 wt% KH550-modified kaolin nanoparticles, were synthesized and characterized using a dielectric strength tester, scanning electron microscope (SEM), dynamic mechanical analysis, thermogravimetric analysis techniques. A suitable addition of kaolin can enhance the mechanical properties, dielectric properties as well as reduce the dielectric loss of kaolin/BADCy copolymer. SEM analysis shows distinct characteristics of ductile fracture of the blends. In addition, the kaolin/BADCy nanocomposites has a better thermal stability compared with BADCy resin with the increasing of kaolin content. The moisture absorption increases linearly with the square root of time, and it follows the Fick’s second law. All these changes in properties are closely correlated to the kaolin/BADCy nanocomposites, which could form an interaction interface structure in the system.

Comparative analysis on dielectric properties of polymer composites reinforced with synthetic and natural fibers

This article presents the study of dielectric properties of synthetic and natural fiber reinforced epoxy composites. Bamboo and glass fibers were both chopped and woven. These fibers were then used for reinforcing epoxy, with different fiber loadings. The dielectric properties of these composites were studied with reference to their fiber loadings, frequencies, and chemical treatment of the natural fibers at room temperature. It was found that dielectric properties increased with the increase in the concentration of fibers filled in the epoxy matrix, for the entire frequency range. This was due to the increase in the orientation and interfacial polarization. The treated fiber composites had lower dielectric properties due to decreased hydrophilicity of the natural fiber. The chopped glass fibers reinforced epoxy composites have the highest dielectric constant, among all tested composites. J. VINYL ADDIT. TECHNOL., 24:E201–E216, 2018. © 2018 Society of Plastics Engineers

Percolation of carbon nanomaterials for high-k polymer nanocomposites

High-k polymer composite materials are next-generation dielectrics that show amazing applications in diverse electrical and electronic devices. Establishing near-percolated network of conducting filler in an insulating polymer matrix is a promising approach to develop flexible high-k dielectrics. However, challenges still exist today on fine controlling the network morphology to achieve extremely high k values and low losses simultaneously. The relationship between the network morphology and the dielectric properties of polymer composites is raising a number of fundamental questions. Herein, recent progress towards high-k polymer composites based on carbon nanomaterials is reviewed. Particular attention is paid on the influence of the network morphology on the dielectric properties. Some perspectives that warrant further investigation in the future are also addressed.

Investigation of dielectric properties of polymer composites reinforced with carbon nanotubes in the frequency band of 0.01 Hz - 10 MHz

The goal of this work is experimental study of dielectric properties of polymer nanocomposites reinforced with multiwalled carbon nanotubes (MWCNTs) in alternating electric field in low frequency band of 0.01 Hz - 10 MHz. We investigated the influence, functionalization degree, aspect ratio, concentration of carbon nanotubes (CNTs) on dielectric properties of polymer sample. We also studied the dependence of dielectric properties on the polymerization temperature. The dependence of CNTs agglomeration on sample polymerization temperature and temperature's influence on conductivity has been shown. We conducted model calculation of percolation threshold and figured out its dependence on CNTs aspect ratio.