Electrical Properties Of Composites Research Articles

Preparation and properties of unsaturated zinc carboxylate/EPDM composites

ABSTRACT The unsaturated zinc carboxylate/Ethylene-Propylene-Diene Monomer (EPDM) composites were prepared by mechanical blending. The effects of hydroxy (2-methylprop-2-enoato-O)zinc (ZMMA) and zinc dimethacrylate (ZDMA) on the hydrophobicity, mechanical properties, ageing resistance, and electrical properties of the composites were studied. The results show that the mechanical properties, crosslinking rate, crosslinking density, and oil resistance of the composite are significantly improved with the increase of ZMMA and ZDMA content. The crosslinking density of EPDM filled with 15 phr of ZDMA composite material is 3.22 × 10−3 mol/cm3, compared with the samples without ZDMA filling, the improvement was 175.2%, and the tensile strength reaches 16.9 MPa, which increases by 33.6%. The addition of a small amount of unsaturated carboxylate has a positive effect on the electrical properties of EPDM matrix composites. The volume resistivity of the EPDM filled with 5 phr of ZDMA is 16.2 × 1013 Ω·m, an increase of 36.1%.

Disk flower-like structure of PANI Modulated electronic transport dynamics of Sr[formula omitted] ferrite

This study conducted a comprehensive analysis of the low frequency-based electrical characteristics of ferrite composites, exploring the influence of morphology on tunning and optimizing dielectric and conductivity relaxation. Specifically, composites of PANI: Sr CoxZnxFe12−2xO19 in 1:4 ratio by weight, with varying levels of substitution x = 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0 were synthesized using the physical blending method. X-ray diffraction analysis of composites shows the existence of M-type hexagonal and PANI particles, along with some secondary phases in all synthesized samples. The morphology of composites revealed disk flower-like and hexagonal platelet-type structures of PANI and hexagonal ferrite, respectively. Substituting Co–Zn ions induced a non-linear increase in grain size from 0.781 to 1.566 μm, calculated using ImageJ software. The dielectric and electrical properties of composites were examined over the frequency range of 20 Hz to 2 MHz. The replacement of Fe ions with Co–Zn ions resulted in a non-linear variation in conductivity and is maximum for FP3 (1.33 × 10−2 Ω−1m−1) at 2 MHz. The complex impedance spectra deviated from an ideal Debye type and were modeled using an equivalent circuit encompassing resistances of grain boundaries and grains, grain capacitance, and a constant phase element. Modulus and impedance spectra analysis illustrated the contribution of both grain and grain boundaries in their respective relaxations. The simulation of impedance parameters in EIS software elucidated a substantial value of Cg = 290 μF for FP1, which aligned with the large-sized grain observed in FESEM micrographs.

Enhancing the mechanical and electrical properties of CNTs/Cu composites by synthesizing WC nanoparticles on the surface of CNTs

The trade-off between mechanical and electrical properties has been a long-standing challenge for carbon nanotubes (CNTs)/Cu composites. To alleviate such trade-off, a pre-decorated strategy, involving the introduction of WC nanoparticles on CNTs (WC@CNTs), is proposed to accomplish the prominent mechanical-electrical property synergy. It was found that WC was epitaxially grown on the CNTs, which renders the epitaxial orientation relationship (OR) as: (WC(001)//CNTs(0002)). Such epitaxial OR facilitates the robust WC-CNTs interface by reducing interfacial energy. Meanwhile, WC nanoparticles also enhance the bonding strength of CNTs-Cu interface by strong mechanical interlocking. The designed “CNTs-WC-Cu” interface not only guarantees accurate stress/strain transmission, but also enhances the interfacial conductivity by reducing interfacial scattering, which contributes to the considerable mechanical and electrical properties of WC@CNTs/Cu over CNTs/Cu. This research provides a feasible strategy for simultaneous improvement of the mechanical and electrical properties of composites.

Design and preparation of low-filled magnetic oriented BN@Fe3O4/EP insulating composite with improved thermal conductivity and thermal stability

As an excellent two-dimensional insulating material with high thermal conductivity, high temperature stability and high hardness, hexagonal boron nitride(h-BN) is widely applied in semiconductor manufacturing, aerospace, metallurgical manufacturing and other cutting-edge fields. However, the unique surface structure of h-BN leads to poor lubricity and easy agglomeration, which limits the application of h-BN especially in the field of electronic packaging. To address key issues boosted above, this study designed and prepared the BN@Fe3O4 magnetic insulating particles and doped it into the reduced viscosity epoxy resin to prepare the composites. By selecting appropriate external magnetic field strength and BN@Fe3O4 particles’ content, a novel 3D structure of fillers like dominoes in epoxy resin composite was successfully constructed. The microstructure of the BN@Fe3O4 particles and composites were analyzed, the thermal conductivity, the mechanical and the electrical properties of composites were simultaneously tested. Results manifested that the core-shell structures with BN as core and Fe3O4 as shell was successfully prepared, linking through the PDA middle layer between the BN core and Fe3O4 shell. Under the influence of magnetic orientation, the BN@Fe3O4 magnetic particles were preferred an out-of-plane oriented in the epoxy resin composites, resulted an enormously enhanced on thermal conductivity of composites. At a magnetic field strength of 60 mT and 25 vol% BN@Fe3O4 content, the thermal conductivity of BN@Fe3O4/EP composites is as lofty as 1.832 W/(m K), which is 1023.46% higher than that of pure epoxy resin. Meanwhile, the thermal stability has also been slightly improved, the elastic modulus and insulation performances remain at the same level.

Nanoparticles produced by laser ablation in organic solvent for polylactic acid-based polymer

Recently packing technology has been rising as a new domain for the application of nanoparticles. Herein the synthesis of polylactic acid (PLA) foils decorated with nanoparticles is investigated. The gold nanoparticles (Au NPs) can play a major role in reducing microbial load in aliment and to improve the food packaging quality. Au NPs have been fabricated by laser ablation in an organic liquid and then the PLA, with Au NP composites, has been manufactured through the drop-casting method. The crystalline nature of the produced nanoparticles, of their size and shape have been probed by transmission electron (TEM) and atomic force microscopies (AFM). The concentration of Au NPs has been evaluated by Rutherford Backscattering Spectrometry (RBS). The optical and electrical properties of composites have been tested by UV–ViS spectroscopy. The improvement of the hydrophobicity of the composite surfaces has been analysed by wettability measurements for implementation in the food packaging field.

Investigation of Dielectric and Mechanical Properties of Pretreated Natural Sunn Hemp Fiber-Reinforced Composite in Correlation with Macromolecular Structure of the Fiber.

The present study attempts to establish a correlation between the macromolecular parameters obtained from small angle X-ray scattering (SAXS) analysis of pretreated sunn hemp (Crotalaria juncea) fibers with the dielectric and mechanical properties of their composites. Sunn hemp fiber is pretreated chemically by dewaxing and alkalization methods and physically by microwave irradiation. The treatment effect is structurally investigated using a correlation function from SAXS data and correlated with the mechanical as well as electrical properties of composites. The macromolecular parameters are observed to be influenced by pretreatment methods. Macromolecular structural modifications are seen in dewaxed fiber (DSHC), fiber treated with 10% of alkali soaked for 6 h (10K6C), and fiber microwave irradiated with 800 watts for 6 min (800W6M), improving the mechanical as well as electric properties of the reinforced composites.

Study on properties influence of carbon fiber reinforced polyimide composites via surface modification using metal mesh

AbstractIn this work, carbon fiber reinforced polyimide (CF/PI) composites via surface modification using metal mesh were obtained. The interfacial adhesion performance of metal mesh and composites, mechanical properties and electrical properties of composites were characterized. The results revealed that introducing metal mesh on CF/PI composites surface obviously decreased the resistivity of composites, which was of great significance for lightning protection. For the mechanical properties, the short‐beam shear strength and flexural properties of modified composites slightly declined, and the failure mode of samples did not change significantly. From microscopic failure morphology and finite element analysis, it can be illustrated that the crack generated from edge may lead to the mechanical properties changes of metal mesh modified sample. Based on practical application condition, the performance change rule of modified composite system after thermal treatment was also reported. This study enables a surface modification thought as a promising way for the application of high temperature resistant CF/PI composite system.

Effect of Structure of Carbonized Polymer Dot on the Mechanical and Electrical Properties of Copper Matrix Composites

Carbonized polymer dots (CPDs) have been paid a lot of attention by researchers because of their excellent properties due to their unique structure. However, few studies have researched the impact of the CPD structure on composite applications. Herein, CPD and heat-treated CPD (h-CPD) are used to fabricate a reinforced Cu matrix composite. There was a semi-coherent interface between h-CPD and Cu. However, functional groups and polymer chains of CPDs decomposed during heat treatment, weakening the mechanical and electrical properties of the composites. These findings show that CPD structural integrity is vital to composites.

Effect of Functionalized Multi-Walled Carbon Nanotubes on Preparation of High Strength and Conductive Copper-CNTs Composites by Electrodeposition

Functionalized multiwalled carbon nanotubes (MWCNTs)-reinforced copper (Cu) composites were prepared by the combination of electrowinning and hot-pressing sintering and cold rolling process. The influence of the functionalization of MWCNTs on the strength and electrical properties of MWCNTs/Cu composites was studied. Functional group was introduced to increase the wetting of water electrolytes, improve the poor wettability of MWCNTs and form a highly active surface suitable for the preparation of MWCNTs/Cu composites by electro-deposition, enabling MWCNTs to be evenly dispersed in Cu matrix. Studies have shown that the addition of 1% of functionalized MWCNTs composite can increase the tensile strength by 6% and 165% compared with the addition of unfunctionalized and pure copper. It’s worth noting that the increase of oxygen-containing functional group brought about by functionalized MWCNTs did not significantly reduce the electrical properties of composites. The main reason for this is the good dispersion of the treated MWCNTs in Cu matrix and the bridging for electronic transmission, ensuring that the high electrical properties of MWCNTs/Cu composites are just slightly lower than those of electrolytic pure copper (99.92% IACS).

Composites between Perovskite and Layered Co-Based Oxides for Modification of the Thermoelectric Efficiency.

The common approach to modify the thermoelectric activity of oxides is based on the concept of selective metal substitution. Herein, we demonstrate an alternative approach based on the formation of multiphase composites, at which the individual components have distinctions in the electric and thermal conductivities. The proof-of-concept includes the formation of multiphase composites between well-defined thermoelectric Co-based oxides: Ni, Fe co-substituted perovskite, LaCo0.8Ni0.1Fe0.1O3 (LCO), and misfit layered Ca3Co4O9. The interfacial chemical and electrical properties of composites are probed with the means of SEM, PEEM/XAS, and XPS tools, as well as the magnetic susceptibility measurements. The thermoelectric power of the multiphase composites is evaluated by the dimensionless figure of merit, ZT, calculated from the independently measured electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (λ). It has been demonstrated that the magnitude’s electric and thermal conductivities depend more significantly on the composite interfaces than the Seebeck coefficient values. As a result, the highest thermoelectric activity is observed at the composite richer on the perovskite (i.e., ZT = 0.34 at 298 K).

Electrical Properties of Composites Based on Low-Pressure Polyethylene and Carbon-Containing Fillers

We have obtained polymer composites based on low-pressure polyethylene and carbon-containing fillers: carbon black, carbon nanotubes. The electrical properties of the obtained polymer composites have been investigated. Obtained polymer composites have electrically conductive properties. This article shows that the electrical properties significantly depend on the concentration, type of carbon-containing filler, as well as on temperature and voltage. It was found that containment of a certain amount of carbon-containing fillers leads to a formation of conductive paths composites, leading to the manifestation of a positive temperature coefficient in electrical resistance by the material.

4D Printing of Lead Zirconate Titanate Piezoelectric Composites Transducer Based on Direct Ink Writing

Lead zirconate titanate (PZT) piezoelectric composites used in transducers were fabricated via direct ink writing (DIW) combined with furnace sintering and resin impregnation. A ceramic slurry with a volume fraction of 52 vol% and suitable viscoelasticity was prepared. After post-process, the PZT ceramic specimens showed a nanoscale grain size with a density of 7.63 g/cm3, accounting for 97.8% of the theoretical density. The effects of different printing rod spacing on the electrical properties of composites were evaluated and lucubrated. Finally, an underwater acoustic transducer was assembled by using the PZT piezoelectric composites fabricated by the above method. The electrical signal generated by the underwater acoustic transducer changed autonomously with the acoustic stimulation, which indicated the application mode of 4D printing in functional devices in the future.

Mechanical properties of natural cellulose fibers reinforced polymer composites – 2015–2020: A review

In the past few decades, synthetic polymers are being reinforced with various filler materials (fibers and particles) to improve and obtain desired properties for particular applications. These materials have been used in the areas of automotive, aerospace, structural and construction, householding, and sports. The plant-based natural cellulose fibers have recently gained increasing attention among researchers as a potential reinforcing agent owing to their high specific properties, renewability, availability, and biodegradable nature. When natural cellulose fibers derived from the plants and vegetables are used as reinforcing agents, they have enhanced the physical, thermal, mechanical, biodegradation, and electrical properties of composites. Natural cellulose fibers are hydrophilic in the environment, which reduces the compatibility with the polymer matrices. Therefore, it is essential to evaluate and understand the mechanical properties of natural fiber reinforced polymer composites for the manufacturing of polymer composites with improved properties. In the present paper, recently (2015–2020) developed the natural cellulose fiber/polymer matrix composites were reviewed according to the variations of mechanical properties.

Influence of mixing methods on the NOx reduction capability and electrical properties of photocatalytic cementitious systems

Nitrogen oxides (NOx), regarded as toxic air pollutants, are a group of highly reactive and hazardous gases encompassing compounds ranging from nitrous to nitric acid. Especially in crowded cities, the release of these gases from the industrial organizations and vehicles has reached serious levels. To eliminate the adverse effects of these gases, titanium dioxide (TiO2) is used worldwide as a photocatalyst due to its high efficiency in oxidization of NOx. Incorporating TiO2 into cement-based composites gives them photocatalytic capability: uniform and stable dispersion of TiO2 throughout the matrix is an undisputable requirement for improved photocatalytic efficiency. The main purpose of this study is to investigate the effects of different mixing techniques and surfactant materials on the dispersion of high dosage nano-TiO2 particles (5% of total weight of binder materials) throughout cement-based materials, with the goal of producing cost-effective cementitious systems, more feasible mixing methods, and ensuring proper dispersion of nano-TiO2. Five different mixing methods were proposed to achieve uniform distribution of the nano-TiO2. They were each implemented using different mixing procedures, equipment and surfactants. The performance of each mixing method was evaluated based on photocatalytic performance, electrical impedance (EI), compressive strength and microstructural analysis. Test results showed evidence of the significantly positive effect of polyacrylic acid (PAA) on the dispersion of nano-TiO2. In general, the highest dispersion occurred with ultrasonication and binary utilization of polycarboxylate ether-based plasticizer (PCE) and PAA. The EI test was a highly effective evaluation method for homogeneous distribution of conductive nano particles throughout the matrix. Results also showed a significant relationship between electrical performance and nitric oxide (NO) degradation of composites, and electrical properties of composites are able to provide a reliable estimate of the photocatalytic efficiency of them.

Electrical properties of composites based on nanoporous carbon material

In this work, the morphological and electrical properties of the composite nanoporous carbon material/thermally expanded graphite or acetylene black have been investigated. Nanoporous carbon material was obtained from plant materials by its thermochemical activation based on potassium hydroxide. The dependence of the specific capacity of the nanoporous carbon/electrolyte electrochemical system on the applied potential was determined by the impedance spectroscopy method. Furthermore, the concentration of charge transfer and the density of states, as well as the flat-band potential of the system under research, were determined based on the Mott-Schottky model.

Impedance study on humidity dependent conductivity of polymer composites with conductive nanofillers

In many previous studies on humidity sensors based on composites embedded with conductive nanofillers, opposite (positive or negative) dependence of their electrical resistance on humidity has been reported. In this study, we systematically investigate the origin of opposite humidity-dependence of the resistance of agarose/carbon nanotube composites (A-CNTs) as a model composite material. Experimental results and impedance analysis reveal that the composites with more conductive fillers present positive dependence of resistance on humidity as an electronic pathway through the well-connected fillers is preferred for electrical conduction. In contrast, the composites with low filler content show negative dependence as the ionic pathway is more dominant for electrical conduction. The corresponding equivalent circuits for the nanofiller-embedded composites are suggested and the expected Nyquist plots depending on the filler content and humidity conditions are discussed. The process based on the impedance analysis potentially allows for non-destructive analysis of compositions and electrical property of composites as well as highly sensitive humidity detection.

Structural, Electrical and Thermal Properties of Composites Based on Conducting Polymer

Abstract: In this work, we report the structural, thermal and electrical properties of composites consisting of polypyrrole particles in a polymethylmethacrylate matrix. Electrical resistivity analysis of these percolating composites showed a remarkable change in the conduction mechanisms below and above the percolation threshold. Structural properties were studied using X-ray diffraction, showing increases in the crystallinity index for filler concentrations above the critical percolation. Thermogravimetric analysis was used to study thermal degradation. It shows a transition from a single peak for concentrations below the percolation threshold to a double peak for concentrations above that point. The increase in the degradation temperature with the concentration of polypyrrole indicates the increase of thermal stability. Keywords: Conducting polymer, Percolation threshold, Crystallinity, Thermal degradation, X-Ray diffraction.

Interfacial bonding enhancement and properties improvement of carbon/copper composites based on nickel doping

ABSTRACT Carbon/copper composites are widely used in collector brushes, pantograph sliders, collector shoes and other fields due to their excellent mechanical friction, wear, thermal conductivity and electrical conductivity. However, the interfacial bonding force of composites is weak because of the natural non-wetting of copper and carbon graphite matrix, which restricts its comprehensive mechanical and electrical properties. In this paper, the nickel element was doped and introduced in the preparation process of the carbon graphite matrix, and the carbon/copper composites were further prepared by the pressure impregnation method. The results showed that the modified carbon matrix doped with nickel was denser, and the nickel element could evenly distribute in the carbon matrix. The porosity of the modified carbon/copper composites was significantly reduced and the interfacial bonding method was changed from the original simple mechanical interlock to solid solution bonding so that the interfacial state was obviously improved. The effect of nickel content on the mechanical and electrical properties of composites was systematically studied. It was found that when the nickel content was 3 wt%, the compressive strength and flexural strength were increased by nearly 52% and 58%, and the electrical conductivity was increased by nearly 35%.

The Influence of Interfaces on the Physicomechanical Properties of Cu/Mg Composites

The structure and the mechanical and electrical properties of composites with 7 and 49 magnesium fibers in the copper matrix are studied in this work. It was found that the strength of a deformed composite wire with the maximum volume fraction of Cu/Mg interfaces exceeds the theoretical estimate and the strength of pure copper. It is shown that deformation-induced formation of high-strength solid solutions of magnesium in copper at the interfaces of the composites occurs during the manufacturing process. The low electrical resistivity of the composites is provided by a copper shell.

Influence of cation interdiffusion on electrical properties of doped ceria/lanthanum silicate composite

La-doped ceria (LDC)/lanthanum silicate (LS) and Ga-doped ceria (GDC)/LS composites were prepared, and the influence of cation interdiffusion during co-firing on the electrical properties of composites was investigated. The electrical conductivity of GDC/LS was lower than that of LDC/LS despite the higher conductivity of GDC compared to LDC. The crystal phases of LDC/LS and GDC/LS were detected as fluorite-type cubic ceria (Fm3‾m) and a hexagonal lanthanum silicate (P63/m), respectively, by X-ray diffraction (XRD). From energy dispersive X-ray spectroscopy (EDS) measurements, it was found that the compositions of the ceria and silicate phases in LDC/LS were nearly stoichiometric after co-firing. In contrast, interdiffusion between Gd3+ in the ceria phase and La3+ in the silicate phase was recognized for the GDC/LS. The compositions of the ceria and silicate phases in GDC/LS after co-firing were estimated as Gd0.035La0.065Ce0.9O1.95 and La7.910Gd0.423(SiO4)6O0.5, respectively. The Gd3+ substitution for La3+ in the silicate phase in GDC/LS decreased the amounts of 4f site cations. Then, the lattice parameter of the silicate phase decreased. As a result, the decrease in electrical conductivity of GDC/LS is attributed to the decrease in the oxide anion at the 2a site, which is a conduction carrier. It was found from Raman spectroscopy that cation interdiffusion decreased the symmetry mode of the SiO4 tetrahedra for the silicate phase in GDC/LS and brought about increases in the activation energy of electrical conductivity for GDC/LS.