Polymer nanocomposites incorporating inorganic nanofillers have emerged as highly promising electromagnetic interference (EMI) shielding materials, combining mechanical compliance with robust conductive percolation networks. Carbon nanotubes (CNTs) are particularly attractive as conductive fillers because their high aspect ratio facilitates percolation at low loadings. Also, CNTs offer superior mechanical durability under deformation compared to rigid, fracture-prone metal nanowires. For EMI shielding, high electrical conductivity is critical as it enhances both reflection and absorption through efficient charge dissipation and conduction losses. However, achieving highly aligned conductive pathways without degrading the intrinsic electrical properties of CNTs remains a significant challenge. Here, we demonstrate a non-destructive magnetic surface-functionalization and alignment strategy. Using a polydopamine (PDA)-mediated route, pristine multiwalled CNTs are uniformly decorated with Fe3O4 nanoparticles (FMWCNTs). This enables highly effective magnetic field-driven alignment at fields as low as 10 mT, promoting the strategic formation of percolation networks. By optimizing the Fe₃O₄/MWCNT ratio for high saturation magnetization and uniform coverage, the aligned FMWCNTs exhibit significant electrical anisotropy, delivering a 10.7-fold higher electrical conductivity in the parallel configuration compared to the vertical configuration. These findings present a scalable, room-temperature platform for engineering directionally enhanced conductivity in polymer nanocomposites, with broad applicability in advanced EMI shielding, flexible electronics, and advanced packaging technologies.
Piezoelectric ceramics play an important role in various electronic applications. However, traditional ceramics are difficult to be used in some complicated structures, due to their low flexibility and high brittleness. To solve this problem, this study prepared and investigated ceramic/polymer composites that can utilize a good flexibility of polymers. Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) and 0.77(Bi1/2Na1/2)TiO3-0.23SrTiO3 (BNST23) ceramics were selected to fabricate the composites. Ceramic/polymer composites were prepared using various volume fractions of BNST23 ceramics. The distribution of piezoceramic particles in BNST23/PVDF-TrFE composites was investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The dielectric and piezoelectric properties of the composites were significantly influenced by the volume fraction of the piezoelectric ceramics. As a result, the highest piezoelectric constant (d33) of 56 pC/N was obtained in a composites with 70% volume fraction of BNST23 ceramics. Accordingly, it is expected that BNST23/PVDF-TrFE composites can be applied to various sensor applications.
Piezoelectric ceramics play an important role in electrical and electronic devices such as sensors, actuators, and microelectronic devices. However, traditional ceramics are difficult to be used in various process industries due to their high brittleness and low flexibility. Therefore, piezoelectric paint sensors have been designed for application to the curved surfaces of complicated structures. Furthermore, recently, significant attention has been focused on the development of paint sensors that can be used as structure health monitoring sensors for vibration, impact, and acoustic emission. Several studies have successfully demonstrated the possibility that smart paint sensors can take the place of traditional ceramic sensors. In this review, we briefly introduce the concept of the piezoelectric paint sensors and the expected application field as well as their preparation and history.
Magnetoelectric (ME) properties of 3-0 type particulate composites have been investigated with respect to application features for reliable magnetic sensitivity and magnetically-induced output voltage. In order to figure out the magnetoelectric characteristics in the ME composites, frequency dependent ME responses were studied from [0.948 Na0.5K0.5NbO3-0.052 LiSbO3]-[Co1-xZnxFe2O4] (NKNLS)/Co1-xZnxFe2O4 (CZFO, x=0, 0.1, and 0.2). As a result, the maximal αME of 23.15 mV/cm·Oe was achieved from the NKNLS-CZFO (xZn = 0.1) composites at resonance frequency of 315 kHz and Hdc = 0 Oe. From the frequency dependent ME responses, it is clearly described that the self-biased ME composites can be used for applications as both magnetic sensors and energy harvesters, respectively.
Since 2010, polymer-based magnetoelectric (ME) composites have been developed with detailed investigations of multiferroic properties such as piezoelectric, magnetostrictive, and magnetoelectric, etc. In particular, as a piezoelectric polymer, poly(vinylidene fluoride) and its co-polymers have been widely used in ME composites for energy harvesting, health monitoring, environment treatment, and bio-medical applications. In this study, main research trend and selected experimental results of polymer-based ME composites are briefly reviewed with respect to composite structure as well as application field. A conclusion was drawn that the polymer-based ME composites would be feasible as flexible devices or functional membranes in the near future.
3YSZ + (x) Al2O3 composites (x = 20, 40, 60, 80 wt%) were fabricated and the influences of particle sizes of Al2O3 on their microstructures and mechanical properties were investigated with XRD, SEM, vickers hardness and fracture toughness. Al2O3-3YSZ composites containing Al2O3 powder of a 0.3 μm and an 1.0 μm, which are here in after named as Al2O3(0.3 μm)-3YSZ and Al2O3 (1.0 μm)-3YSZ, respectively, were made by mixing raw materials, uni-axial pressing and sintering at 1,400℃, 1,500℃, and 1,600℃. Al2O3 (0.3 μm)-3YSZ composites show the higher density and the better mechanical properties than Al2O3 (1.0 μm)-3YSZ composites. The Vickers hardness of the Al2O3 (0.3 μm)-3YSZ composites show a peak value of 1,997 Hv at the content of 60 wt% Al2O3, which is a slightly higher value in comparison with 1,938 Hv of the Al2O3(1.0 μm)-3YSZ composite. However, the fracture toughness of Al2O3-3YSZ composites monotonically increases with decreasing the content of Al2O3 without any peak values. Al2O3 (0.3 μm)-3YSZ and Al2O3 (1.0 μm)-3YSZ composites sintered at 1,600℃ have a maximum value of a 6.9 MPa·m1/2 and a 6.2 MPa·m1/2, respectively at the composition of containing 20 wt% Al2O3. It should be noticed that the mechanical properties and the sintering density of the Al2O3-3YSZ composites can be enhanced by using more fine Al2O3 powder due to their denser microstructure and smaller grain size.
In order to develop an electrical insulation material for gas GIS (insulation switch gear) spacer, 4 types of epoxy/micro-alumina (40, 50, 60, 70 wt%) composites and 9 types of epoxy/nano-alumina (1, 3, 5 g)/micro-alumina (40, 50, 60, 70 wt%) composites were prepared and tensile test was carried out. In here, nano-alumina was previously surface-treated with GDE (glycerol diglycidyl ether). As micro-alumina and GDE-treated nano-alumina contents increased, tensile strength increased and the highest value was shown in the system with 3 g GDE-treated nano-alumina.
The aim of this study is to improve of dielectric properties using epoxy/nano alumina composites with adding glycerol diglycidyl ether (GDE:1,2 g). This paper deals with the effects of dielectric properties(□´ and tan δ) for epoxy/nano alumina contents (1,3 phr) and GDE addition (1,2 g)composites. 5 kinds specimen were prepared with containing epoxy resins, epoxy nano alumina composites. Average particle size of nano used were 30 nm. The nano alumina used were gamma phase particles of spherical shape. The suppression of epoxy chain motion by addition of nano alumina+GDE decreased dielectric loss and relative permittivity magnitude.
In this work, the complex permittivity of epoxy resins is measured. Epoxy resins, epoxy with micro size fillers and epoxy with micro+nano alumina composites have been evaluated for dielectric properties according to frequency variation. The dielectric spectroscopy measurement and analyses are carried out in the frequency range of 10-2 Hz to 1MHz and constant to room temperature. The results of dielectric loss suggest that significant improvement in the electrical performance can be expected by using samples containing nano and micro fillers mixture when compared to materials containing only microfillers. As the result, we verified the specific characteristics of dielectric permittivity and dielectric loss namely, relative permittivity become low with improving dispersibility of nano+micro mixture composites and become rise with agglomerate of nano particles.
(YNdSm)-Ba-Cu-O system high Tc composite superconductors were directionally grown by zone melting process, having large temperature gradient, in air atmosphere. Cylindrical green rods of (YNdSm)1.8Ba2.4Cu3.4Ox [(YNS)1.8]composite oxides by CIP (cold isostatic pressing) method using rubber mold were fabricated. Themicrostructure and superconducting properties were investigated by XRD, TEM and SQUID magnetometer. The size of nonsuperconducting (YNdSm)2BaCuO5 inclusions of the melt-textured (YNS)1.8 sample with CeO2 additive were remarkably reduced and uniformly distributed within the superconducting (YNS)1.8 matrix. (YNS)1.8 samples, with / without CeO2 additive, showed an onset Tc ≥ 90 K and sharp superconducting transition. The critical current density Jc value of the (YNdSm)1.8 superconductor with CeO2 additive were 840 A, 1.2×104 A/cm2 in 77 K, 0Tesla by direct current transport method.
Molded insulation materials are widely used from large electric power transformer apparatus to small electrical machinery and apparatus. In this study, by adding MgO with the average particle of several tens nm and the excellent thermal conductivity into molding material, we improved the problem of insulation breakdown strength decrease according to rising temperature in overload or in bad environmental condition. We confirmed the life evaluation by using the insulation breakdown and inverse involution to investigate the electrical characteristics of nano-composites materials. By using a scanning electron microscope, it is confirmed that MgO power with the average particle size of several tens nm is distributed and the filler particles is uniformly distributed in the cross section of specimens. And it is confirmed that the insulation breakdown strength of Virgin specimens is rapidly decreased at the high temperature area. But it is confirmed that the insulation breakdown strength of specimens added MgO slow decreased by thermal properties in the high temperature area improved by the contribution of the heat radiation of MgO and the suppression of tree. The results of life prediction using inverse involution, it is confirmed that the life of nano-composites is improved by contribution of MgO according to the predicted insulation breakdown strength after 10 years of specimens added 5.0 wt% of MgO is increased about 2.9 times at RT, and 4.9 times at 100 than Virgin specimen, respectively.
In order to develop a high voltage insulation material, spherical silicas with two average particle sizes of 5 μm and 20 μm were mixed in different mixing ratios (1:0, 0.7:0.3, 0.5:0.5, 0.3:0.7, 0:1) and their total filling content was fixed at 65 wt%. In order to observe the dispersion of the spherical silicas and the interfacial morphology between silica and epoxy matrix, field emission scanning electron microscope (FE-SEM) was used. The electrical insulation breakdown strength was estimated in sphere-plate electrodes with different insulation thicknesses of 1, 2, and 3 mm. Electrical insulation breakdown strength decreased with increasing mixing ratio of 5/20 μm and the thickness dependence of the breakdown strength was also observed. The tensile strength of the neat epoxy was 82.8 MPa as average value and its increased with decreasing particles size and that of epoxy/silica (2 μm) was 107 MPa, which was 130.8% higher value.
The composites composed of conducting polymer (MEH-PPV), CdTe nanoparticles, and multiwalled carbon nanotubes (MWNTs) were spectroscopically and electrically characterized in their thin films. The composite films were prepared by spray coating. These composites were prepared from the mixture solution of MEH-PPV and CdTe-embedded MWNTs, in which CdTe nanoparticles were electrostatically bound to MWNTs. UV/vis and PL spectra were analyzed to investigate the optical absorbance and emission of the composite films. In addition, their structural, electrochemical, and electrical properties were studied by transmission electron microscopy, cyclic voltammetry, and I-V measurement.
This paper presents a study on the dispersion effect of the X-Ray diffraction, glass transition and DIMA properties of organic modifier clay/epoxy nanocomposites produced in a homogenizer. Several experiments were conducted including different types of dispersion condition with varying processing conditions such as homogenizer rotor speed and applied time of homogenizer. The effects of these variables on the dispersion properties of nanocomposites were then studied. In order to fully understand the experimental results, a X-ray diffraction, DSC and DMA were used to investigate the effect of above mentioned variables on microstructure and intercalation/exfoliation of organic modifier clay/epoxy nanocomposites. The results from this work could be used to determine the best processing condition to obtain appropriate levels of d-spacing, glasss transition temperature and storage modulus in organic modifier clay/epoxy nanocomposites.
In order to develop electrical insulation materials, epoxy-nanosilica-microsilica mixture composites (ENMC) was synthesized, and mechanical properties such as their tensile and flexural strength, and AC insulation breakdown strength were investigated. Properties of mechanical strength and AC insulation breakdown strength are analyzed as scale and shape parameter with respect to weibull plot. Their tensile and flexural strength, AC insulation breakdown strength were compared original epoxy or EMC to ENMC. The 4 phr nano-silica addition and the 65 wt% micron-silica mixture composite (ENMC) was found to have the highest tensile and flexural strength. In the tensile strength was improved 29%, and flexural strength was improved 60.9% higher than those of the original epoxy. In the insulation breakdown strength, ENMC_4 phr was improved 17% and ENMC_5 phr was improved 15.8% higher than those of the EMC.
In order to application for high voltage heavy electric equipments, epoxy/microsilica 60 wt%/nano layered silicate composites (EMNC_60) and epoxy/microsilica 65 wt%/nano layered silicate composites (EMNC_65) respectively was synthesized by our electric field dispersion method and the result was obtained completely dispersion state. Thermal properties such as glass transition temperature (Tg) and thermal expansion coefficient, and DMA characteristics were studied, and mechanical properties such as tensile and flexural tests were performed. AC electrical insulation strength was also tested. The study on thermal property, EMNC_65 was better than EMNC_60 and mechanical ,electrical properties much improved EMNC_60 compared with EMNC_65.
This research shows the electrical characteristic using excellent epoxy nano-composite of MgO 5.0 wt% and SiO2 0.4 wt% in mechanical strength test depending on nano-additive. First of all, volume resistance depending on nano-additive and temperature using high resistance meter (HP. 4329A) by increasing 10, 100, 1,000 V of applying voltage was measured. Moreover, temperature range of 25~120℃ with virgin sample was tested using TO-9B oven by Ando Company. The result showed that virgin and the samples added with MgO and SiO2 had similar value of volume resistance in low temperature and low electric field region and reduced with slow slope. The nano-composite`s volume resistance of sample added with MgO and SiO2 had higher value than virgin sample`s volume resistance in high temperature region more than 80℃. Moreover, the slope has steeply reduced. The volume resistance of sample added with MgO 5.0 wt% was 8.38×10(13) Ω·cm and it was 6.8 times more than virgin sample in high temperature at 120℃. The insulation characteristics were constant although filler has changed in low temperature region. But, in high temperature region, the value of volume resistance of sample with MgO 5.0 wt% was 7.6 times more than the virgin sample`s volume resistance.
Three-dimensionally ordered macro-porous Sn-C composites were prepared by using polystyrene microsphere as a template. The Sn-C composites were composed of well-interconnected pore with circular shape and wall structure with wall thickness of a few tens of nano-meters. This porous three-dimensional structure is readily and uniformly accessible to the electrolyte, which facilitates lithium ion diffusion during charge-discharge reactions. The wall thickness of the composites was increased as the increase of Sn content of the composite. From EDS analysis, it is confirmed that the Sn was dispersed uniformly in Sn-C composites. The capacity was increased as the Sn content increased, which is due to Sn anode with high capacity. The Sn-C composites with high Sn content showed superior cyclic performances. Such enhancement is ascribed to the thick wall thickness and small pore size of the sample with high Sn content. The Sn-C composite with Sn 30 wt% showed relatively high capacity and stable cycle life, however, the stability of the 3-dimensional structure should be enhanced by further work.
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