Electrical Conductivity Of Composite Material Research Articles

Improvement of electrical conductivity in glass bubble-carbon nanotube/polyamide 6 hybrid scale composite through novel mechanical forming and segregated network morphology

The study suggests that GB-CNT/PA6 multiscale hybrid composite can be used to create a network structure with controllable electrical conductivity, making it a promising material for various practical applications. The paper introduces a new method for controlling electrical conductivity of composite materials by creating a segregated network morphology (SNM) using a glass bubble (GB)-carbon nanotube (CNT)/polyamide 6 (PA6) multiscale hybrid composite. Instead of relying solely on CNTs, the addition of GB allows for a more economical process by reducing the required CNT concentration to achieve the desired electrical conductivity. The paper also analyzes the effects of varying GB and CNT content on electrical conductivity based on percolation theory. The results demonstrate an 18.8 times increase in electrical conductivity with the SNM approach. The study proposes that this approach could be used to create composite materials with controllable electrical conductivity, making them suitable for various applications.

Electrical Conductivity of Composite Materials Based on n-InSe and Thermally Expanded Graphite

Electrical Conductivity of Composite Materials Based on n-InSe and Thermally Expanded Graphite

The effect of reinforcing with fibers and nanomaterials on the electrical properties of composite materials

Technological development depends mainly on the progress of materials so that materials must be able to withstand service conditions. Accordingly, we always move towards composite materials, by combining two or more materials and often have different properties, so that the two materials work together to give unique composite properties. The aim of this study is to study the electrical properties represented by insulation and electrical conductivity of composite materials (including epoxy (95%) and phenol formaldehyde (5%)) supported by graphite nanoparticles and glass fibers.

Влияние методов формирования полимерных композитных материалов с углеродными нанотрубками на механизмы электропроводности

The influence of the method of formation of nanostructured polymer composites filled with carbon nanotubes to their electrophysical properties was carried out. The influence of the «size effect» of multi-walled carbon nanotubes, functionalization method, and ultrasonic treatment method on the electrical conductivity of composite materials in the frequency range 50 Hz - 5 MHz and the temperature range 15 - 375 K has been established. The presence of various mechanisms of electric transport in composite materials that affect the final value of electrical conductivity is established. The best results of electrophysical parameters are observed with a combination of non-covalent functionalization of nanotubes and high-power ultrasonic exposure. This method allows us to achieve a conductivity value of composite materials of 0.01 S/cm in the studied frequency range at a filler concentration of 0.5 wt.%.

Interphase approach for modeling the DC conductivity of diverse allotropic types of carbon-reinforced polymer composites

This work is based on a generalized effective medium-modified model for predicting the DC electrical conductivity of polymer composites, taken into account the interactions between the components using an interphase approach. Generalized effective medium-modified model is a simple extension of the Generalized Effective Medium Theory proposed by McLachlan. We studied the modeling of the DC electrical conductivity using the proposed model for diverse allotropic types of carbon-reinforced polymer composites. Three series of composite materials obtained by mixing an insulating matrix DGEBA with (i) carbon nanotubes which are one-dimensional materials (1 D), (ii) reduced graphene oxide, which is a two-dimensional material (2 D) and (iii) carbon black, which is a three-dimensional material (3 D) have been studied. Predictions from the model are in good agreement with the experimental data of the electrical conductivity of composite materials, where the classical models have not been able to explain them. Moreover, in this paper, the effects of the filler dimension on the interphase properties of the composite materials, in particular the interphase volume fraction and the interphase conductivity, have been investigated.

Phenomenon of the percolation in composite materials based on a polymer binder with a dispersed filler phase

The paper presents the experimental results of studies of the thermal conductivity and electrical conductivity of composite materials based on dimethylsiloxane SKTN A and carbon black filler. The percolation and their similarity in the processes of heat transfer and electrical conductivity are analyzed. The correspondence of experimentally observed percolation threshold values to theoretical descriptions is discussed.

Electrically Conductive Composite based on Functionalized Carbon Nanotubes/Epoxy Resin

This work is devoted to the study of the effect of carbon nanotubes functionalization on the electrical conductivity of composite materials based on them. Carbon nanotubes were functionalized by treatment in nitric acid and isopropyl alcohol. Changes in the morphology of multi-walled carbon nanotubes during liquid-phase functionalization were investigated using Auger-electron microscopy. Samples of composite material on the basis of initial and functionalized carbon nanotubes and epoxy resin were prepared and the concentration dependence of electrical conductivity using the four-probe method was studied. The study reveals the effect of functionalization in various solutions on the electrophysical properties of the obtained carbon nanotubes/epoxy composites.

Structural health monitoring of carbon fiber reinforced matrix by the resistance variation method

In this work, electrical resistance change method is used for carbon fiber reinforced thermoplastic polymers damage monitoring. The electrical resistance variation could be an interesting complementary to existing/classical damage monitoring methods. It is extremely attributed to electrical conductivity of composite material and it appears that enhancing the conductivity of materials, by the use of conductive nanofillers in our case, improves their sensitivity to mechanical loading. Carbon fiber reinforced thermoplastic polymers with different nanofillers types and concentrations were manufactured and tested in tensile loading. Concentration of 0 and 8 wt% of carbon black and 2.5 wt% of carbon nanotubes were used with Polyamide 6 sheets as matrix. Nanofillers weakening effect was discussed according to their concentrations and types. The acoustic emission, digital image correlation and in-situ microscopy were also recorded during testing. A correlation between all these signals and the evolution of the electrical resistance of the composites during the tensile loading was performed. It was found that CB enhances sensitivity of carbon fiber reinforced thermoplastic polymers to damage detection, especially delamination. For the carbon nanotubes, results are less promising. A discussion is held about the nanofillers concentration influence.

Identification of concentration dependences of the electrical conductivity of composite materials of SiC‒TiN and SiC‒ZrN systems

An explanation of the physical nature of the experimentally established concentration dependences of the electrical conductivity of ceramic composite materials of the SiCTiN (ZrN) system is proposed. A model of the structure and a method for calculating the electrical conductivity of composite materials, as well as experimental dependences of the electrical conductivity of sintered ceramics of the SiC‒TiN (ZrN) system are presented.

Identification of Concentration Dependences of the Electrical Conductivity of Composite Materials of SiC–TiN and SiC–ZrN Systems

An explanation of the physical nature of the experimentally determined concentration dependences of the electrical conductivity of ceramic composite materials of the SiC–TiN (ZrN) system is proposed. A model of the structure and a method for calculating the electrical conductivity of composite materials, as well as experimental dependences of the electrical conductivity of sintered ceramics of the SiC–TiN(ZrN) system are presented.

AlF3 coating as sulfur immobilizers in cathode material for high performance lithium-sulfur batteries

Although the rechargeable lithium-sulfur battery is an advanced energy storage system, their practical implementation has been impeded by many issues, in particular the ‘shuttle effect’ causing rapid capacity fade and low coulombic efficiency. Herein, the AlF3 coating, prepared via a facile solution-based method, is used as sulfur immobilizers in cathodes for Li–S batteries for the first time. The physical confinement, chemical anchoring and catalysis conversion for polysulfide are achieved simultaneously through the existence of the AlF3 coating, which is confirmed by experimental results. Meanwhile, the CNTs improved the electrical conductivity of composite materials significantly, and a suitable three-dimensional conductive framework was formed to accommodate sulfur. Due to these merits, the as-designed composite materials of carbon nanotubes-sulfur coating by aluminum fluoride (CNTs-S@AlF3) cathode exhibited excellent electrochemical properties and stable capacity retention. The initial discharge capacity reaches 1144.1 mAh g−1 and after 250 cycles is 783 mAh g−1 at 1 C, which is much higher than the composite materials of without AlF3 coating. Moreover, the CNTs-S@AlF3 cathode presents excellent long-term capacity stability with a capacity decay of 0.062% per cycle during 1000 cycles at 0.5 C, offering a potentiality for use in high energy Li–S batteries.

Structure and electrophysical properties of composite materials based on vacuum residue and low density polyethylene

The structure and specific electrical conductivity of composite materials based on vacuum residue and low density polyethylene has been studied. It is shown that changes in the properties of composites correspond to changes in the degree of structural heterogeneity.

Control Quality of Composite Materials by Using Subminiature Eddy Current Transducers

Based eddy current transducer (ECT), a probe has been designed to research composite materials. Defects inspection of composite materials is performed to determine the following standard defects: defect of the metallic and (or) polymer layer uniformity. The subminiature ECT of the original design is used as a sensor in this device, it is made according to a differential scheme of switching on of the coils of a transformer ECT and allowing to localize the control area up to 0.1-0.5 mm. The measurement procedure allowing one to detect defects in composite materials with a high accuracy is described. The sensor was tested on the composite material consisting of paper or low-density polyethylene and aluminum layers in which the model defect was placed. The dependences of the ECT signal on the defect in this structure are given. The determined dependence of electrical conductivity of composite materials on model defects make it possible to carry out defects inspection of composite materials.

Optimised trajectory calculation for the automated layup of wide lightning protection tapes on double-curved fuselage sections

Lighting strike protection is not intrinsically provided on modern composite built aircraft due to the lower electrical conductivity of composite materials. A highly conductive copper foil is manually applied onto the fuselage in multiple overlapping tapes. Known automation processes are not adequate for wide tapes particularly in the case of large double-curved surfaces. One key technology for enabling an automated process is tape trajectory generation with a focus on automation constraints. We are introducing a new tape application mechanism for a single wide tape. Our algorithm generates geometry induced layup trajectories, taking into account geometric conditions. We experimentally demonstrate a wrinkle-free automated application. Based on the first algorithm, a second algorithm addresses the challenging issue of an optimised surface coverage with multiple tapes for a fuselage section. A tape application fitness criterion is defined and implemented. We point out that a computer-based algorithm is advantageous for determining the proper arrangement of multiple tapes. It is thus now possible to create a multiple tape design that can be applied with an automation process. In addition, the optimisation leads to a reduction of consumed and wasted tape material in the fuselage production process.

Thermal and Electrical Conductivity of Copper-Fluoroplast Composites Produced by Explosive Pressing

In this paper, we carried out comparative experimental studies of the effect of static and explosive pressing on the thermal and electrical conductivity of composite materials based on Fluoroplast-4 containing 10 to 40 vol % of copper powder. Explosive pressing was found to promote an increase in the thermal and electrical conductivity of composite materials. This is likely attributed to the increased adhesion between copper and Fluoroplast-4.

Computation of effective electrical conductivity of composite materials: A novel approach based on analysis of graphs

In this work we continue the investigation of different approaches to conception and modelling of composite materials. The global method we focus on, is called ‘stochastic homogenization’. In this approach, the classical deterministic homogenization techniques and procedures are used to compute the macroscopic parameters of a composite starting from its microscopic properties. The stochastic part is due to averaging over some series of samples, and the fact that these samples fit into the concept of RVE (Representative Volume Element) in order to reduce the variance effect.In this article, we present a novel method for computation of effective electric properties of composites – it is based on the analysis of the connectivity graph (and the respective adjacency matrix) for each sample of a composite material. We describe how this matrix is constructed in order to take into account complex microscopic geometry. We also explain what we mean by homogenization procedure for electrical conductivity, and how the constructed matrix is related to the problem. The developed method is applied to a test study of the influence of micromorphology of composites materials on their conductivity.

Influence of TiC Content on Microstructure and Properties of W-30Cu/TiC Composites

W-30Cu/ x TiC ( x= 0∼4, wt%) composite powders were prepared by electroless plating with simplified pretreatment. The composite powders were formed by cold compaction under 400 MPa using a tablet machine and green compactions were sintered at 1300 °C for 1 h. Micromorphology of the original W and TiC powders, simple-treated W and TiC powders, and as-received W-30Cu/ x TiC ( x= 0∼4) composite powders after electroless plating were characterized by field emission scanning electron microscopy (FE-SEM). Microstructures of the W-30Cu/ x TiC ( x= 0∼4) composites were also investigated by FE-SEM. The effect of TiC content on the properties of W-30Cu/ x TiC ( x= 0∼4) composites (such as relative density, hardness, electrical conductivity, and compressive strength) were studied. Results show that W-30Cu/TiC composite powders with uniform structure are obtained by simplified W and TiC powder pretreatment, followed by electroless copper plating. When TiC content is less than 1 wt%, the compressive strength and hardness of composite materials obviously increase and the electrical conductivity of composite materials decreases with TiC content increasing. However, the electrical conductivity of composite materials is still higher than that of the national standard value. With a certain amount of TiC content to W-30Cu/ x TiC ( x= 0∼4) composites, the composites exhibit good comprehensive performance.

Effect of graphite sizes and carbon black content on flowability of the injection molded conductive composite material

This study is to investigate the flowability of the injection molded conductive composite material containing filler content from 70 up to 80 wt% by using spiral mold. Several moulding compounds, containing polypropylene (PP) as a matrix and graphite (G) and carbon black (CB) as conductive fillers prepared by melt compounding using twin-screw extruder. Carbon black is added as much as 10% and 20% respectively, in order to improve the electrical conductivity of composite material. Results show that the flowability of injection molded conductive composite material decreases with decreasing graphite size and with increasing filler (graphite and carbon black) content. It was found that composites containing G with particle size distribution (≤100 μm) entirely exhibits a relatively higher flowability, in the range of 10.67–6.21 cm, compared to the small size (25-60 μm), in which flowability is in the range of 5.23–3.37 cm. An attempt to combine carbon black as second filler with the PP and G found that composites containing CB showed decreased flowability of the injection molded conductive composite material, especially when the electrical conductivity formed through the resin. Results indicate that the flowability of the injection molded conductive composite material is an important design parameter to fabricate cost-effective, large, or thin composite bipolar plates.

Electrically Conductive Polymer Composite Dispensing Process for EMI Shielding Structure

Electro Magnetic Interference (EMI) shielding structure with low cost and high performance is proposed. Conductive polymer composite is formulated with metal based filler and silicone polymer and solvent. The liquid composite material can be easily dispensed through the low pressure injection nozzle and cured to the conformal structure with high aspect ratio. High electro conductive polymer composite dispensing process is developed to build a conformal structure for the EMI shielding of PBA(Printed Board Assembly). In order to increase electrical conductivity of composite material, Ag coated copper is adopted for conductive filler material and dendrite structure is applied to reduce content ratio of the conductive filler in the composite material. An EMI shielding structure is designed to cover the exposed surface of the chip package and modified for the shielding module containing chips and electrical elements on the PBA. The wall thickness of shielding layer is under 0.6mm and aspect ratio is lower than 2.0. The conformal structure is fabricated by dispensing process with side slot nozzle and viscoelastic behavior of composite material maintains the vertical thin wall structure. EMI shielding performance is verified by measurement of chip level EMI shielding test procedure developed in this study.

Simulation of electrical percolation in disperse systems at a small difference between specific conductivities of components

The possibility of development of electrical percolation upon variations in the contents of components in a disperse system has been studied in terms of Bruggeman’s ideas of an effective medium and the continual model of the electrical conductivity of composite materials. The case of a small difference between the specific conductivities of a dispersed phase K m and a dispersion medium K d has been considered. It has been shown that the dependence of electrical conductivity K of a disperse system on volume fraction p of a wellconducting component may exhibit an inflection in the vicinity of the p* value, which depends on the K m/K d ratio. Different methods for determining the p* value have been described. At low ratios between the conductivities of a dispersed phase and a dispersion medium, the inflection is very weakly pronounced. However, the representation of the K(p) dependences in semilog coordinated substantially facilitates its identification.