Ferroelectric Filler Research Articles

Adjustment of dielectric performances for polymer-inorganic composites by ferroelectric filler modification with graphene micro-additive

The modification of a ferroelectic filler (barium titanate BaTiO3) with graphene nanoplates deposited from aqueous dispersions is shown to strongly affect the dielectric performances of composites prepared by the incorporation of thus modified filler into cyanoethyl ester of polyvinyl alcohol (CEPVA) as a polymer binder. The increase of graphene content from 0.2 to 1.6 mg/g results in oscillating changes of permittivity and dielectric losses of the composites, whereas the further increase of the additive amount leads to a steady growth of both performances. The observed effects are found to correlate with specific centers on the filler surface responsible for the filler-binder interaction. The deposited graphene amount is optimized to provide a simultaneous significant increase of dielectric permittivity and decrease of the dielectric loss.

Energy storage enhancement of P(VDF-TrFE-CFE)-based composites with double-shell structured BZCT nanofibers of parallel and orthogonal configurations

Recent research in the development of flexible polymer dielectric materials for the conversion of electrical energy is springing up. A state-of-the-art energy-storage polymer-based composite with the potential of improving the performances (energy-storage density and efficiency) at the low electric field strength is proposed here. The ferroelectric polymer P(VDF-TrFE-CFE) (PVTC) blending with linear polymethyl methacrylate (PMMA) is used as the matrix to ensure higher polarization and lower energy loss. Meanwhile, the inorganic 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZCT) nanofibers work as the filler, and the double transition layers of core-shell structure (Al2O3+SiO2) serve as the interface. Finally, P(VDF-TrFE-CFE)-based composites with double-shell structured BZCT nanofibers of parallel and orthogonal configurations were fabricated. The effects of microstructure information (matrix, filler, interface) together with different configurations (parallel and orthogonal configurations) of BZCT@Al2O3@SiO2 nanofibers on the performances of nanocomposites were systematically and primarily discussed. Importantly, the Orthogonal BZCT@A@S⊥PVTC + PM composite with 3 vol% BZCT@A@S NFs possessed an excellent discharged energy density (~20.1 J/cm3) with charge-discharge efficiency of ~58.6% at ~440 kV/mm; meanwhile, the in-plane thermal conductivity of it reaches to ~0.33 W/(m·K). Referring to the experimental findings and simulation results, a mechanism related to rapidly polarized ferroelectric filler was proposed.

Dielectric/ferroelectric properties of ferroelectric ceramic dispersed poly(vinylidene fluoride) with enhanced β-phase formation

Abstract Free standing and flexible ferroelectric ceramic-polymer composites (PVDF+ ϕ wt.% of BNBT (0.94Na0.5Bi0.5TiO3-0.06BaTiO3)) with 0–3 connectivity were synthesized by solution-casting technique. Composite nature and homogeneous distribution of ceramic filler particles in PVDF were confirmed with x-ray diffraction and scanning electron microscopic analysis. The intensity ratio of β-phase with respect to α–phase i.e., I20.2°/I18.4° (obtained from XRD analysis) and the fraction of electro-active beta phase i.e., F(β)% (obtained from FTIR analysis) are enhanced with increase in filler concentrations and peaked for 35 wt% of the ceramic filler. An enhancement of the % of crystallinity (calculated from XRD analysis) has been observed with increase in the filler concentrations. The increase of the fraction of β-phase has been explained on the basis of ion (negatively charged surface ion of the ferroelectric ceramic filler) -dipole (-CH2 dipole of the polymer matrix) interactions, as evidenced from FTIR and UV-VIS absorbance spectra. Relative dielectric permittivity (dielectric constant) and ferroelectric polarization were found to be highest for the composite with 35 wt% of ferroelectric ceramic filler. Percolation theory has been successfully employed to explain the observed trend in the dielectric properties with the compositional variation. Significant enhancement in the electro active β-phase has been correlated with the improved dielectric and ferroelectric properties of the composite.

Ferroelectric properties of composite films based on polystyrene

This article considers the preparation and investigation of the composite films based on polystyrene with ferroelectric filler. It shows that the permittivity is linearly dependent on the filler concentration. Ferroelectric properties starting appear from the concentration values from 20% to 35%. Due to the polystyrene matrix composite films have high breakdown strength.

Advancing Dielectric and Ferroelectric Properties of Piezoelectric Polymers by Combining Graphene and Ferroelectric Ceramic Additives for Energy Storage Applications.

To address the limitations of piezoelectric polymers which have a low dielectric constant andto improve their dielectric and ferroelectric efficiency for energy storage applications, we designed and characterized a new hybrid composite that contains polyvinylidene fluoride as a dielectric polymer matrix combined with graphene platelets as a conductive and barium titanite as ceramic ferroelectric fillers. Different graphene/barium titanate/polyvinylidene fluoride nanocomposite films were synthesized by changing the concentration of graphene and barium titanate to explore the impact of each component and their potential synergetic effect on dielectric and ferroelectric properties of the composite. Results showed that with an increase in the barium titanate fraction, dielectric efficiency ofthe nanocomposite was improved. Among all synthesized nanocomposite films, graphene/barium titanate/polyvinylidene fluoride nanocomposite in the weight ratio of 0.15:0.5:1 exhibited thehighest dielectric constant of 199 at 40 Hz, i.e., 15 fold greater than that of neat polyvinylidene fluoride film at the same frequency, and possessed a low loss tangent of 0.6. However, AC conductivity and ferroelectric properties of graphene/barium titanate/polyvinylidene fluoride nanocomposite films were enhanced with an increase in the graphene weight fraction. Graphene/barium titanate/polyvinylidene fluoride nanocomposite films with a weight ratio of 0.2:0.1:1 possessed a high AC conductivity of 1.2 × 10−4 S/m at 40 Hz. While remanent polarization, coercive field, and loop area of the same sample were 0.9 μC/cm2, 9.78 kV/cm, and 24.5 μC/cm2·V, respectively. Our results showed that a combination of graphene and ferroelectric ceramic additives are an excellent approach to significantly advance the performance of dielectric and ferroelectric properties of piezoelectric polymers for broad applications including energy storage.

Polymer composites with balanced dielectric constant and loss via constructing trilayer architecture

Polymers with high dielectric constants are widely used in electronic devices and electric systems. However, polymers exhibit low dielectric constants, which greatly limit their applications. Currently, ferroelectric ceramic fillers and conductive filler are commonly filled into polymer matrix to achieve enhanced dielectric constants. Unfortunately, even though the loading fraction of ferroelectric ceramic fillers exceeds 50 vol%, the enhancement of dielectric constant is still limited. On the contrary, although ultrahigh dielectric constant could be realized in conductor/polymer composites containing small loading fractions of conductive fillers, the loss is usually very high owing to severe leakage conduction. To overcome the shortcomings of the above-mentioned two types of high dielectric composites, this work combined them together and designed a series of trilayer polymer composites consisting of one carbon nanotube/polyimide composite layer sandwiched by two BaTiO3/polyimide composite layers. Fortunately, the trilayer architecture could effectively overcome the drawbacks of carbon nanotube/polyimide and BaTiO3/polyimide single-layer composites, hence the balanced dielectric constant and loss. When the BT content of the outer layer is 50 wt% and the carbon nanotube content of the middle layer is 4 wt%, the trilayer film possesses a high dielectric constant of ~ 35 @10 kHz, which is about 700% over pristine PI matrix (e′ ≈ 5 @10 kHz). Meanwhile, the loss tangent of the trilayer composite (tanδ ≈ 0.03 @10 kHz) is still comparative to pristine PI (tanδ ≈ 0.01 @10 kHz).

Comparative study of dielectric properties of the PVDF composites filled with spherical and rod-like BaTiO3 derived by molten salt synthesis method

In the molten salt environment, the BaTiO3 spherical nanoparticles (BTNPs) and BaTiO3 nanorods (BTNRs) have been synthesized, respectively, in which spherical TiO2 and rod-like BaTi2O5 are precursors. The dissolution–precipitation is the main dominated mechanism in the formation of BTNPs, while the dissolution–diffusion is the main mechanism responsible for the formation of BTNRs. The latter is also called as topochemical mechanism, which is associated with the assembly of [TiO6] octahedron units in the transformation from BaTi2O5 to BaTiO3. By using these two kinds of BT as fillers, polyvinylidene fluoride (PVDF)-based composites, BTNPs/PVDF and BTNRs/PVDF, have been constructed and their dielectric properties have been investigated. It was found that there were three main factors related to filler morphology affecting the dielectric properties of the composites, i.e., intrinsic polarization of filler, the interface polarization and electric field distribution between the filler and the matrix. Though the spontaneous polarization of 600-nm-sized BTNPs is larger, the interfacial area of BTNRs/PVDF composite is larger than that of BTNPs (600 nm)/PVDF composite, which is advantageous to enhance the interface polarization. Moreover, the analysis through Potential-Across model revealed that BTNRs/PVDF composite has stronger electric field intensity distribution across BTNRs filler in comparison with BTNPs/PVDF, which plays the key role in improving the dielectric properties of composites. This work not only presents the BTNRs/PVDF composite with good dielectric performance, the related design and the theory analysis also facilitate the development of more new high dielectric composites based on morphology control of ferroelectric filler.

High discharged energy density of polymer nanocomposites containing paraelectric SrTiO3 nanowires for flexible energy storage device

Nanocomposites combining high permittivity ferroelectric nanofillers and high breakdown strength polymer have shown tremendous potential for pulsed power applications. Nevertheless, the discharged energy density and efficiency of these nanocomposites filled with ferroelectric fillers are limited due to the large remanent polarization of ferroelectric fillers employed. Here, uniform elongated morphology paraelectric SrTiO3 nanowires fillers were synthesized via a special stirring hydrothermal method. The fabricated P(VDF-CTFE)-based nanocomposites containing 3 vol% paraelectric SrTiO3 nanowires exhibit an enhanced discharged energy density of 8.8 J/cm3 at 3381 kV/cm, which exceeds most of the current reports at the same electric field. By direct comparison study with ferroelectric BaTiO3 nanowires fillers, the results show paraelectric SrTiO3 nanowires can simultaneously improve the discharged energy density and efficiency more effectively. Such enhancement in energy storage performance can be attributed to the following reasons: (I) The enhanced breakdown strength, which resulted from the reduced inhomogeneous electric fields via adopting the SrTiO3 nanowires with lower permittivity. (II) The paraelectric phase SrTiO3 nanowires show little hysteresis behavior compared to ferroelectric phase BaTiO3 nanowires. This work is of critical significance in making advanced dielectric nanocomposites that are viable for energy storage devices in current electronic and electrical applications.

Effect of SiO2 Coating Layer on CCTO Particles on Properties of CCTO/PVDF Composites

The ceramic-polymer composites are attracted many researchers attention to using as energy storage. The purpose to get both high breakdown field and high polarization. It is very important to use the high dielectric material as a filler in the polymer matrix to obtain both properties. In many research, ferroelectric fillers like BaTiO3, PbZrO3, BaSrTiO3 have been widely used due to their high dielectric performance [1]. One of the promising materials in this area is CCTO due to showing dielectric constant up to 105 [2-3] The CCTO performance as an energy storage is limited due to low breakdown field and high energy loss. One of the acceptable ways to address this problem is making a composite with a polymer to enhance breakdown field. The ferroelectric polymer like PVDF exhibits high dielectric constant while keep breakdown field high [4-5]. The effect of the SiO2 coating layer and CCTO concentration mixed with PVDF has been studied. The polymer based composites of PVDF/SiO2/CCTO were made by a spin coating process, in which DMF was used as the solvent. The CCTO powders were coated by SiO2 using sol-gel method. The P-E loop test was conducted to measure the energy storage of different composites. The results show an increase in breakdown field while the P-E loop becomes slimmer by making a composite with SiO2. The polarization increased, due to enhancement in the dielectric constant of the composites because of a good connection between matrix and filler made by the additive. The microstructure was studied by using SEM pictures, which shows a better connection between fillers and matrix. The XRD has been used to illustrate the change in the crystallization. The improvement in both polarization and breakdown field make the composite suitable for energy storage usage. Fig. 1. P-E loop of polymer composites Refrences: 1- Ke Yu, Hong Wang, Yongcun Zhou, Yuanyuan Bai, and Yujuan Niu, Enhanced dielectric properties of BaTiO3/poly(vinylidene fluoride) nanocomposites for energy storage applications, J. Appl. Phys. 113, 034105 (2013). 2- Laijun Liu, Yanmin Huang, Yunhua Li, Danping Shi, Shaoying Zheng, Shuangshuang Wu, Liang Fang, Changzheng Hu. Dielectric and non-Ohmic properties of CaCu3Ti4O12 ceramics modified with NiO, SnO2, SiO2, and Al2O3 additives. J Mater Sci (2012) 47:2294–2299 3- Qiaoli Zhang, Tao Li, Zhenping Chen, Renzhong Xue, Yongqiang Wang, The non-ohmic and dielectric behavior evolution of CaCu3Ti4O12 after heat treatments in oxygen-rich atmosphere. Materials Science and Engineering B 177 (2012) 168–172 4- Mojtaba Rahimabady, Shuting Chen, Kui Yao, Francis Eng Hock Tay, and Li Lu, High electric breakdown strength and energy density in vinylidene fluorideoligomer/poly(vinylidene fluoride) blend thin films, Appl. Phys. Lett. 99, 142901 (2011) 5- M. Mohammadi, P. Alizadeh, F.J. Clemens, Effect of SiO2 on sintering and dielectric properties of CaCu3Ti4O12 nanofibers, Journal of Alloys and Compounds 688 (2016) 270e279 Figure 1

Enhanced Dielectric Performance of Polymer Nanocomposites Based on CNT/MnO2 Nanowire Hybrid Nanostructure

We report a new highly efficient polymer nanocomposite for charge storage applications based on carbon nanotube (CNT) and MnO2 nanowire (MnO2NW). Our study suggested that combination of conductive filler (CNT) and ferroelectric filler (MnO2NW) is an effective method to fabricate nanocomposite with outstanding dielectric permittivity and low dielectric loss if two fillers share similar length and geometry. This strategy leads us to fabricate a hybrid nanocomposite (CNT:MnO2NW (3.0:4.5 wt %)) with a high dielectric permittivity (50.6) and low dielectric loss (0.7), which are among the best-reported values in the literature in the X-band frequency range (8.2–12.4 GHz). We postulated that superior dielectric properties of the new hybrid nanocomposites were attributed to (i) better dispersion state of CNT in the presence of MnO2NW, which increases the effective surface area of CNTs, as nanoelectrodes, (ii) dimensionality match between the nanofillers, which increases their synergy, and (iii) barrier role of Mn...

Enhanced dielectric properties of polyimide/BaTiO3 nanocomposite by embedding the polypyrrole@polyimide core-shell nanoparticles

A three-phase polymer composite with a ferroelectric phase (BaTiO3) and conductive core-shell polypyrrole@ polyimide (PPy@PI) nanoparticles embedded in a polyimide (PI) matrix was prepared by using a simple direct mixing and solution casting process. PPy@PI nanoparticles as the conductive filler were synthesized to obtain homogeneous dispersion in the PI matrix. The dependence of the dielectric behavior on the BaTiO3 and PPy@PI contents was studied over a wide frequency range from 10 kHz to 1 MHz. The incorporation of low loading levels of PPy@PI nanoparticles to the PI/BaTiO3 system led to a significant enhancement in the dielectric constant with suppressed loss. The dielectric constant (Dk) of the PI/BaTiO3/PPy@PI (25/75/5) hybrid was 58.53 at 10 kHz, i.e., three times higher than that of the PI/BaTiO3 (25/75) nanocomposite without PPy@PI. The fairly improved dielectric properties were due to the synergistic enhancement of the ferroelectric ceramic filler, BaTiO3, and conductive filler, PPy@PI nanoparticles, as well as due to homogeneous dispersion. Such polymer composites have the potential for use in fabricating embedded capacitors, and specimens with various shapes can be easily obtained owing to the flexibility of the nanocomposite.

Enhanced dielectric properties and energy storage density of interface controlled ferroelectric BCZT-epoxy nanocomposites

Polymer nanocomposites with ferroelectric fillers are promising materials for modern power electronics that include energy storage devices. Ferroelectric filler, Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) nanopowder, was synthesized by sol-gel method. X-ray diffraction (XRD) studies confirmed the phase purity and the particle size distribution was determined by transmission electron microscopy (TEM). Extended aromatic ligand in the form of naphthyl phosphate (NPh) was chosen for surface passivation of BCZT nanoparticles. Surface functionalization was validated by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and impedance spectroscopy using slurry technique. The dielectric constant of surface-passivated BCZT nanopowder was ~155, whereas pristine BCZT nanopowder dielectric constant could not be assessed due to high innate surface conductivity. Furthermore, BCZT–epoxy nanocomposite films were prepared and analyzed by differential scanning calorimetry (DSC), dielectric spectroscopy, dielectric breakdown strength (DBS), and scanning electron microscopy (SEM). Owning to stronger polymer–particle interface, dielectric measurements of 5 vol.% NPh surface functionalized BCZT–epoxy nanocomposites indicated improved DBS and glass transition temperature (Tg), reduced dielectric loss, and enhanced energy storage density compared to untreated BCZT–epoxy composites and pure epoxy. The energy storage density of 30 vol.% NPh surface functionalized BCZT–epoxy nanocomposite of 20 μm film thickness was almost three times that of pure epoxy polymer of identical film thickness.

Significantly enhanced energy storage performance promoted by ultimate sized ferroelectric BaTiO3 fillers in nanocomposite films

Polymer nanocomposite that consists of dispersed particle fillers and a flexible polymer matrix shows comprehensive excellent dielectric properties and thus is considered as promising dielectric layers in high-performance energy-storage capacitors. However, the commonly employed high permittivity particle fillers cause inevitable dielectric strength deterioration and seriously impede the energy density and reliability of the nanocomposite. To solve this problem, ultimate sized ferroelectric nanofillers, 6.9nm BaTiO3 nanocrystals, are introduced into a poly(vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) polymer matrix to realize both the high dielectric constant and enhanced breakdown strength. The influence of nanoparticle fraction on the microstructure and dielectric properties of the composite films is investigated. Compared to the polymer-ceramic composites with coarse particle fillers, significantly enhanced breakdown strengths (≥330kV/mm) are observed in the nanocomposite films containing 10–40 vol.% BaTiO3 nanofillers. In consequence, a maximal discharged energy density of 9.7J/cm3 is obtained, which confirms that these ultimate sized nanocrystals can perform as superior high permittivity fillers in the nanocomposites for energy storage applications.

A facile one step conversion of the sub-micrometer to uniform nanopowder in tetragonal BaTiO3 via a surface active etching salt

A reasonable design of nanoscale ferroelectric ceramic fillers, with well-controlled shape and size, has become very interesting in modern energy storage applications. A convenient “top-down” process was proposed to obtain nanoparticle products of tetragonal barium titanate (BaTiO3) with highly accurate stoichiometry and morphological control. The key point of this work emphasized that a micrometer-sized precursor decreases to nanometer-sized product particles, and its irregular shape changes to nearly spherical with narrow size distribution. Both XRD and Raman results of BaTiO3 nanoparticles indicated a tetragonal crystal structure. The 77.5±2.5nm sized BaTiO3 powder product still polarized spontaneously at room temperature and the ferroelectric phase transition was confirmed at around 127°C. Dielectric permittivity was found to be ~166.42 by Landauer-Bruggeman effective medium approximation (LB-RMA). Experimental procedures revealed a possible process mechanism observed within the etched surface and Oriented-attachment growth models, and this demonstrated approach could be used as an excellent platform for preparing ceramic nanoparticles. It also could be extended to synthesize complex oxide of functional materials for the preparation of other ceramic/polymer-based nanocomposites that achieve desirable properties.

Effect of particle size and volume fraction of BaTiO3 powders on the functional properties of BaTiO3/poly(ε-caprolactone) composites

A systematic study concerning the effect of particle size and volume fraction of BaTiO3 filler on the functional properties of composite materials with poly-(ε-caprolactone) polymer matrix obtained by solvent casting method was performed. Two series of xBT-(1-x)PCL composites prepared by using BaTiO3 powders with two different particles size (60 nm and 400 nm) in different amounts (x = 2; 5; 10 and 20 vol %) were investigated. The X-ray diffraction analysis indicated a particle size dependence of phase symmetry for BT filler powders (cubic phase for ultrafine particles and tetragonal phase for larger particles size) and the formation of pure composites consisting of orthorhombic PCL and cubic or tetragonal BT with no chemical reactions between them. The micrographs of the composites revealed the formation of homogeneous composites with two distinct phases, a good dispersion of ferroelectric phase into the polymer matrix and a low content of air pores. Dielectric investigations at room temperature showed the increases of permittivity with increasing the particle volume fraction of ferroelectric filler as result of the “sum property” of the effective permittivity in composites. For a given concentration, the permittivity of composites increases with particle size, as result of a size effect of BT powder. The composites with low BT addition presents stable dielectric properties at bending cycles. The polarization-field dependences also show a BT-induced size dependence, i.e. at a given value of field, polarization is higher for the composites with coarser BT particles. The composition x = 0.05 with coarse particles can be considered as an optimum among these series for the stored energy density.

Impedance and dielectric studies of nanocomposite polymer electrolyte systems using MMT and ferroelectric fillers

Impedance and dielectric properties of nanocomposite polymer electrolyte systems modified with nano size MMT and ferroelectric fillers have been investigated for varying lithium to oxygen ratios. The changes in the structural properties of the electrolyte samples were characterized by X-ray diffraction (XRD) and differential scanning calorimetric (DSC) technique. The ion transport number estimated by DC polarization technique is found to be between 0.86 and 0.95. The bulk conductivities of nanocomposite polymer electrolyte films were studied using impedance spectroscopic technique. The impedance plot shows high frequency semicircle, due to the bulk effect of sample and maximum ionic conductivity of 2.15 × 10−4 Scm−1 was observed for (PEO)4LiCBSM at 323 K with lithium to oxygen ratio 1: 4. The complex impedance data was used to evaluate ionic conductivity and dielectric relaxation process, to understand the ion transport mechanism in these systems.

An Analytical Model for Porous Polymer-Ceramic Capacitive Pressure Sensors

An analytical model for pressure sensors is constructed, predicting the capacitive response of a porous, polymer-ceramic composite under an applied pressure. Consisting of mechanical and dielectric counterparts, the iterative model is constructed in detail. The elastic modulus of the three-phase material is approximated by first considering only the polymer-ceramic composite mixture, and then incorporating porosity into the solid composite model. A new model has been developed for approximating the changing elastic modulus of porous polymers undergoing quasi-static compression, which induces the collapsing pores. Necessary material constants were obtained from experimental data published in literature. The permittivity of the paraelectric polymer matrix is modeled, accounting for piezodielectric effects imposed by external pressure and thermally induced stresses caused by substrate pinning. Similarly, the ferroelectric ceramic filler is modeled, considering changes in polarization caused by thermally induced phase transformations in the crystal structure. The final model is evaluated against experimental data, providing insight into composition and microstructure effects on the sensor response.

Field enhanced Li ion conduction in nanoferroelectric modified polymer electrolyte systems

Nanocomposite polymer electrolyte (NCPE) films based on polyethylene oxide (PEO) complexed with lithium perchlorate (LiClO4) and nanosized ferroelectric ceramic fillers such as BaTiO3, SrTiO3 have been prepared using solution cast technique. The films showed very good mechanical stability when exposed to ambient atmospheres for prolonged periods. Lithium ion transport studies revealed that the conductivity is predominantly ionic. The effect of electric field on ionic conductivity of NCPE films was investigated. One order enhancement in conductivity due to the field was observed at 323 K. NCPE films exhibited conductivity of 3.46 × 10−5 Scm−1 at 323 K. NCPE films were characterized using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) technique. The DSC and XRD studies revealed reduced crystallinity which confirmed the higher amorphous phase and hence the improved ionic conductivity.

Lead zirconate (PbZrO3) embedded in natural rubber as electroactive elastomer composites

Perovskite lead zirconate ( PbZrO 3) was synthesized in an orthorhombic form at a temperature below the Curie temperature, TC. The orthorhombic form is a noncentrosymmetric structure which is capable of spontaneous polarization. Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) patterns confirm the successful synthesis of the lead zirconate; and scanning electron microscopy (SEM) micrographs indicate that PbZrO 3 particles are moderately dispersed in the natural rubber (NR) matrix. Without an electrical field, the particles merely act as a ferroelectric filler, which can absorb and store additional stress. Under an electrical field, particle-induced dipole moments are generated, leading to interparticle interaction and a substantial increase in the storage modulus. At a small amount of lead zirconate particulates present in the natural rubber matrix, at a volume fraction of 0.007306, the electrical conductivity increases dramatically by nearly two orders of magnitude at the electrical frequency of 500 kHz.

Polyimide/BaTiO3/MWCNTs three-phase nanocomposites fabricated by electrospinning with enhanced dielectric properties

A three-phase nanocomposite with outstanding dielectric properties was prepared via electrospinning and hot-pressing, by which multi-walled carbon nanotubes (MWCNTs) were homogeneously dispersed in polyimide (PI) matrix and separated by the BaTiO3 particles (BTPs). The fairly enhanced dielectric properties were due to synergistic enhancing of the ferroelectric ceramic filler BTPs and conductive filler MWCNTs. The investigation shows that the dielectric permittivity of the as-fabricated three-phase nanocomposites with 40vol% BTPs and 10vol% MWCNTs loads is as high as 1061.98 at 100Hz with a lower dielectric loss of 0.23, and the corresponding energy storage density is 4.773J/cm3, 11 times that of the pure polyimide. The three-phase nanocomposites with enhanced dielectric properties also show excellent thermal properties and will be attractive in application in modern microelectronics.