Enhancement Of Electrical Conductivity Research Articles

Electrical conductivity enhancement of chopped carbon fiber‐reinforced epoxy composite bipolar plate for proton exchange membrane fuel cells

Electrical conductivity enhancement of chopped carbon fiber‐reinforced epoxy composite bipolar plate for proton exchange membrane fuel cells

Effect of carbon coating on improved electrical and electrochemical performance of Li3Co2SbO6

Abstract We reported a novel high voltage cathode having layered structure and manifold improvement (144%) in electrochemical performance on carbon coating Li3Co2SbO6. The carbon-coated Li3Co2SbO6 has been prepared using a high temperature solid-state method in an air medium with appropriate stoichiometry of the oxide and carbon source (sucrose). The x-ray diffraction and high-resolution transmission electron microscopy results have confirmed homogeneous carbon coating on oxide (Li3Co2SbO6) surface without disturbing phase, structure and morphology. The immediate effect of carbon coating resulted in electrical conductivity enhancement of the carbon coated Li3Co2SbO6 by four order of magnitudes ∼2.79 × 10−4 Scm−1 at room temperature vis-a-vis pristine Li3Co2SbO6. The electrochemical performance of the carbon coated Li3Co2SbO6 has shown sustainable improvement indicating redox activity by more than one Li+ transaction. The carbon coated Li3Co2SbO6 cathode exhibited an initial discharge capacity of 110 mAhg−1 compared to 45 mAhg−1 for its pristine counterpart. The improvement in electrochemical capacity on carbon coating, as reported in this work, is the highest ever compared to prior literature reports on Li3Co2SbO6.

Conductive Graphene–Polyethylene Terephthalate Composite Yarns with Synergistic Multiwalled Carbon Nanotube Additives by Melt‐Spinning

Conductive graphene yarns are pivotal for embedding electronic and intelligent capabilities into fabrics. The study presents successful fabrication of conductive graphene–polyethylene terephthalate (PET) composite yarns with synergistic multiwalled carbon nanotube (MWCNT) additives through the melt‐spinning process, a widely used industrial method for polymer yarn manufacturing. The integration of MWCNTs significantly improves yarns’ electrical conductivity, achieving nearly a 100‐fold increase compared to MWCNT–PET composite yarns. The electrical performance of these yarns is primarily determined by interfacial contacts between conducting nanomaterials, which can be conceptualized as quantum tunneling barriers with multiple molecular energy levels at their extremities. Employing the Simmons model, the current–voltage characteristics is analyzed through a segmented fitting approach to extract critical barrier parameters. The equivalent barrier height and width remain constant across variations in applied voltage, nanomaterial concentration, and temperature. However, the effective total contact area increases significantly with higher nanomaterial contents, thereby substantially boosting the yarns’ electrical conductivity. The larger graphene size (≈200 nm) in comparison with the MWCNT diameter (≈5 nm) results in a substantially greater interfacial area at graphene–MWCNT contacts compared to MWCNT–MWCNT contacts. This disparity in contact area is the primary factor contributing to synergistic enhancement of electrical conductivity in graphene–PET composite yarns.

High-Performance Sodium-Ion Batteries with Graphene: An Overview of Recent Developments and Design.

Due to their low production cost, sodium-ion batteries (SIBs) are considered attractive alternatives to lithium-ion batteries (LIBs) for next generation sustainable and large-scale energy storage systems. However, during the charge/discharge cycle, a large volume strain is resulted due to the presence of a large radius of sodium ions and high molar compared to lithium ions, which further leads to poor cyclic stability and lower reversible capacity. In the past, researchers have devoted significant efforts to explore various anode materials to achieve SIBs with high energy density. Hence, as a promising anode material for SIBs, the two-dimensional (2D) materials including graphene and its derivatives and metal oxides have attracted remarkable attention due to their layered structure and superior physical and chemical properties. The inclusion of graphene and metal oxides with other nanomaterials in electrodes have led to the significant enhancements in electrical conductivity, reaction kinetics, capacity, rate performance and accommodating the large volume change respectively. Moreover, these 2D materials facilitated large surface areas and shorter paths for sodium ion adsorption and transportation respectively. In this review article, the fabrication techniques, structural configuration, sodium ion storage mechanism and its electrochemical performances will be introduced. Subsequently, an insight into the recent advancements in SIBs associated with 2D anode materials (graphene, graphene oxide (GO), transition metal oxides etc.) and other graphene-like elementary analogues (germanene, stanine etc.) as anode materials respectively will be discussed. Finally, the key challenges and future perspectives of SIBs towards enhancing the sodium storage performance of graphene-based electrode materials are discussed. In summary, we believe that this review will shed light on the path towards achieving long-cycling life, low operation cost and safe SIBs with high energy density using 2D anode materials and to be suitably commercialized for large-scale energy storage applications in the future.

Ethanol recognition based on carbon quantum dots sensitized Ti3C2Tx MXene and its enhancement effect of ultraviolet condition under low temperature

The deteriorating air quality makes it particularly important to detect all kinds of harmful gases in the air. In this study, the Ti3C2Tx MXene/CQDs composite was formed by modifying carbon quantum dots (CQDs) to the surface of Ti3C2Tx MXene, in which the Ti3C2Tx MXene sensitized by CQDs achieved enhanced recognition of ethanol. After a series of characterizations, it was confirmed that CQDs were indeed modified on the surface of Ti3C2Tx MXene. The gas sensing test results show that the sensor based on Ti3C2Tx MXene/CQDs composite exhibits excellent response performance to ethanol, particularly achieving a high response value of 15.38–50 ppm ethanol at the optimal operating temperature of 140 °C. Furthermore, this composite also demonstrates excellent repeatability and a stable response relationship towards ethanol. Finally, it is found by comparison that the recovery time of the sensor under ultraviolet (UV) irradiation is significantly shortened, which further verifies that the sensor has wider application potential under UV condition. The experimental results show that the Ti3C2Tx MXene/CQDs composite significantly improves the efficiency and ability of detecting ethanol by optimization of photoresponsive performance, enhancement of electrical conductivity, and increase in specific surface area. This paper provides practical research methods and ideas for the development of novel sensors based on CQDs and Ti3C2Tx MXene.

Modulating electronic by construction WS2/WN heterostructure coupled with N-doped carbon to boost alkaline seawater hydrogen production

The development of an efficient and durable non-precious electrocatalyst for alkaline seawater electrolysis is of great significance. Herein, two-dimensional (2D) lamellar heterostructure WS2/WN was dispersed on the carbon matrix (marked as WS2/WN@CM). The obtained WS2/WN@CM catalysts demonstrate exceptional performance in the hydrogen evolution reaction (HER) in alkaline freshwater (1.0 M KOH), alkaline simulated seawater (1.0 M KOH + 0.5 M NaCl) and alkaline natural seawater (1.0 M KOH + seawater), respectively, which achieved a low overpotential (92 mV, 95 mV and 113 mV) at 10 mA cm−2 and outstanding long-term durability at 200 mA cm−2 for 100 h. The catalyst benefits from the 3D carbon skeleton, which not only effectively prevents stacking of the 2D lamellar WS2/WN to fully utilize the active material, but also provides rapid electron transport. Moreover, stress effects at WS2/WN interfaces lead to distortions of torsion angles in the WS2 lattice, thereby increasing crystal surface defects accompanied by an enhancement of electrical conductivity. Density functional theory (DFT) calculations combined with XPS evidence confirm the electronic structure reorganization of WS2/WN at interfaces, which optimizes the adsorption energy of specific intermediates. Additionally, WN captures many electrons from WS2, so the WN region favors the reduction reaction and thus enhances the HER process.

Study on thermoelectric properties and atomic-scale mechanism of B-site molybdenum-modified La0.1Sr0.9TiO3

Extensive studies on strontium titanate thermoelectric materials have shown that their poor conductivity results in a low ZT value. However, elemental doping can effectively improve the thermoelectric properties of these materials. In this study, a two-step sintering process was applied, using physical mixing to introduce 1 % molybdenum powder as a modification to the lanthanum-doped strontium titanate solid powder (La0.1Sr0.9TiO3). The obtained sample exhibited a maximum conductivity of 7830 S/m, with a maximum ZT of 0.12. Furthermore, this study combined experimental data with first-principles simulation calculations to elucidate the mechanism at the atomic scale. The incorporation of Mo6+ in place of Ti4+ at the B-site by molybdenum (Mo) adds two free electrons, leading to an elevated carrier concentration. This change concurrently reduces the Fermi level of the material and improves mobility, collectively resulting in a substantial increase in electrical conductivity. Phonon simulation indicated that Mo doping increased structural defects, thereby reducing lattice thermal conductivity. This significant enhancement in electrical conductivity and decrease in lattice thermal conductivity collectively increased the ZT value of the material.

Oxygen vacancy induced electrical conductivity enhancement in Ca-doped BiFeO3 thin films

Bismuth ferrite, recognized for its exceptional physical properties as a multiferroic material, has recently attracted considerable attention due to its high domain wall conduction. However, challenges in further improving domain wall conductivity and magnetoelectric coupling hamper the practical application of pure-phase BFO thin films. Addressing these limitations, we successfully synthesized Bi1-xCaxFeO3 thin films on LaAlO₃ (001) substrates with varied calcium (Ca) doping levels (x = 0–0.3) through pulsed laser deposition. Our experimental data demonstrate a direct relationship between the films' electrical conductivity and the prevalence of oxygen vacancies (OV). An upward trend in both OV density and electrical conductivity emerges with incremental Ca doping, peaking at x = 0.2. Beyond this doping threshold, a further increase in Ca concentration inversely affects OV density and electrical conductivity. These insights suggest that fine-tuning OV concentration in Ca-doped BFO thin films can significantly modulate their electrical properties, paving the way for the advancement of bismuth ferrite-based electronic devices.

Insights on the electrical conductivity enhancement mechanisms of carbon polymer dots (CPDs) reinforced Cu composites

Carbon polymer dots (CPDs) has represented unique potential in reconciling the incompatible properties of strength and electrical conductivity (EC) in copper matrix composites, while the mechanisms underlying EC improvement remain to be fully elucidated. 0.2CPDs/Cu composites prepared by conventional powder metallurgy processes achieves excellent mechanical and electrical conductivity simultaneously. Compared to pure Cu, CPDs not only participated in the construction of a better electronic transport pathway, but accelerated the twinning forming behavior, leading to outstanding strength(~423 MPa) and electrical conductivity(95%IACS). Here the conductive behavior of CPDs/Cu composites was revealed through characterizing the intrinsic electrical properties of CPDs and composites microstructure evolution. CPDs not only participated in the construction of a better electronic transport pathway, but accelerated the twinning forming behavior. Increased twinning domain leads to the remarkable amelioration of grain boundary resistance, meanwhile, the intragranular CPDs made a significant contribution on the enhanced mechanical strength via Orowan strengthening. This work makes up the lack of understanding on the mechanical and electrical enhancement mechanism in our prior research.

Enhancing the thermoelectric properties of PEDOT:PSS films through the incorporation of g-C3N4 nanosheets and carbon nanotubes

Present study focuses on the synthesis of flexible nanocomposite film made of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), graphitic carbon nitride (g-C3N4) nanosheets, and carbon nanotubes (CNTs) and how the g-C3N4 nanosheets and CNTs affect the thermoelectric properties of PEDOT:PSS. Incorporating 10 wt% of g-C3N4 nanosheets to PEDOT:PSS improved the Seebeck coefficient to 74.3 μVK−1, ∼5 times higher than the PEDOT:PSS film. However, this led to a decrease in electrical conductivity, limiting the power factor to 335.4 μWm−1K−2. In order to address this, CNTs were added as conductive fillers. The resulting PEDOT:PSS composite, with 10 wt% of g-C3N4 and 10 wt% CNTs, showed a significant power factor of 589.8 μWm−1K−2, an electrical conductivity of 810.6 Scm−1, and a Seebeck coefficient of 84.5 μVK−1, indicating a substantial improvement in the thermoelectric performance of pristine PEDOT:PSS. The increased Seebeck coefficient in the PEDOT:PSS and g-C3N4 composite is due to reduced carrier concentration and energy filtering at the interfaces. The enhancement in electrical conductivity and the Seebeck coefficient after adding CNTs is attributed to the formation of conductive networks, increased mobility, and energy filtering at the interfaces between PEDOT:PSS and CNTs. The study suggests that combining g-C3N4 nanosheets and CNTs with PEDOT:PSS could enhance the thermoelectric performance of PEDOT:PSS-based materials.

Synthesis and characterization of graphene on copper foil via atmospheric pressure chemical vapor deposition method and its impact on electrical properties

Copper, prized for its exceptional electrical conductivity, thermal conductivity, and mechanical strength, is a staple in electronic applications. The ongoing quest for enhanced performance in miniaturized technologies has led to exploring copper-graphene composites, particularly those integrating bilayer graphene (BLG). This study investigates the enhancement of electrical conductivity in copper through the incorporation of BLG via atmospheric pressure chemical vapor deposition (APCVD). The research highlights the APCVD method's ability to grow high-quality BLG on high-purity oxygen-free copper foil, demonstrating significant improvements in electrical properties. Detailed characterization reveal that the graphene growth process induces structural changes in the copper, promoting ideal crystallographic orientations and larger grain sizes. This process achieves nearly complete graphene coverage and results in a copper/graphene (Cu/GR) composite with minimal defects. The electrical conductivity of the Cu/GR composite significantly increased to 59.32 × 10⁶ S·m⁻1, a 7.83 % improvement over the pristine copper foil. This enhancement is attributed to the increased carrier density and mobility within the composite. These advancements suggest the potential of APCVD-grown graphene for various high-performance electronic applications, providing a promising pathway for further development and optimization of graphene-copper composites.

A disposable electrochemical sensor for amyloid-β42 protein based on molecular imprinted polymers with nitrogen doped carbon dots-graphene nanohybrid

This work presented a molecularly imprinted polymer (MIP) electrochemical sensor for determination of amyloid-β42 (Aβ42) as an Alzheimer’s disease (AD) biomarker. A nitrogen-doped carbon-dot-graphene (NCD-G) nanohybrid was synthesized through a simple ultrasonic method. Polypyrrole (PPY) was used as an imprinted polymer with an Aβ42 template for the electropolymerization process. The NCD-G and MIP were modified on a screen-printed carbon electrode (SPCE) without binding agent. The morphology and electrochemical properties of MIP/NCD-G modified SPCE were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and square wave voltammetry (SWV). The developed sensor exhibited good linear response in a range from 5 to 70 pg/mL with a limit of detection (LOD) of 1 pg/mL under optimal conditions. This sensor shows excellent performance due to the enhancement of effective surface area, electrical conductivity, and electrocatalytic activity. This MIP sensor takes advantage of molecularly imprinted technique combined with nanohybrid to achieve high selectivity and sensitivity. Moreover, it possessed good reproducibility and miniaturization that could be applied as a platform for portable devices in healthcare in the future. Novelty statementThis work provides the combination of a zero-dimensional and two-dimensional materials, nitrogen doped carbon dots-graphene nanohybrid (NCD-G) by self-assembly through a simple ultrasonication method and applied as a molecularly imprinted polymer (MIP) sensor for determination of amyloid-β42 protein. We propose a minimum number of preparation steps which NCD-G could enhance the MIP sensor performance, owing to the synergistic effects with high selectivity and sensitivity. The hybrid formation of the carbon dots with graphene using their π-π interactions in carbon nanostructures. NCD-G nanohybrid and MIP modified on screen printed carbon electrode (SPCE) for the determination of amyloid-β42 have not been previously investigated. Moreover, this disposable strip is a single-use tool that might be essential for on-site devices.

Synergistic Enhancement of Mechanical Properties and Electrical Conductivity of Immiscible Bimetal: A Case Study on W–Cu

Immiscible bimetal systems, of which tungsten–copper (W–Cu) is a typical representative, have crucial applications in fields requiring both mechanical and physical properties. Nevertheless, it is a major challenge to determine how to give full play to the advantages of the two phases of the bimetal and achieve outstanding comprehensive properties. In this study, an ultrafine-grained W–Cu bimetal with spatially connected Cu and specific W islands was fabricated through a designed powder-mixing process and subsequent rapid low-temperature sintering. The prepared bimetal concurrently has a high yield strength, large plastic strain, and high electrical conductivity. The stress distribution and strain response of individual phases in different types of W–Cu bimetals under loading were quantified by means of a simulation. The high yield strength of the reported bimetal results from the microstructure refinement and high contiguity of the grains in the W islands, which enhance the contribution of W to the total plastic deformation of the bimetal. The high electrical conductivity is attributed to the increased mean free path of the Cu and the reduced proportion of phase boundaries due to the specific phase combination of W islands and Cu. This work provides new insight into modulating phase configuration in immiscible metallic composites to achieve high-level multi-objective properties.

Effects of mechanical alloying methods on structural phase stability, chemical state, optical, electrical and ferroelectric properties in Sc-doped α-Fe2O3 system

The development of metal doped α-Fe2O3 (hematite) based wide band gap semiconductors with high electrical conductivity, high electrical polarization and wide optical band gap is a challenging problem and also useful for application point of view. In this work, a substantial enhancement of electrical conductivity, optical band gap and ferroelectric polarization have been recorded at room temperature for Sc doped α-Fe2O3 system. Two different methods of the mechanical alloying and subsequent heat treatment have been used to synthesize the samples of α-Fe2-xScxO3 oxide (x = 0.2–1.0). The X-ray diffraction patterns have confirmed formation of single-phased Rhombohedral structure for low Sc doping content (x = 0.2), whereas a mixture of Rhombohedral-structured α-Fe2O3 type phase and cubic-structured Sc2O3 type phase has been formed for the higher Sc contents (x = 0.5 and 1.0). The phase fractions varied depending on the amount of Sc content, chemical reaction during mechanical alloying of the elementary oxides and solid-state reaction during the heat treatment. Response of the Sc2O3 type phase in Raman spectra is sensitive depending on the methods of inter-mixing the α-Fe2O3 and Sc2O3 by mechanical alloying. X-ray photoelectron spectroscopy (XPS) confirmed the metal (Fe, Sc) ions in +3 charge state, although the samples for low Sc content x = 0.2 showed a signature of Fe+2 and Sc+4 states. A detailed analysis of the Fe 3s XPS band confirmed a strong 3s-3d spins exchange coupling of strengths 1.18 eV–1.34 eV.

Electronic and adsorption properties of halogen molecule X2 (X=F, Cl) adsorbed arsenene: First-principles study

The geometry, electronic structure, and adsorption properties of halogen molecule X2(X = F, Cl) on arsenene were investigated using first-principles calculations. The adsorption of molecules was considered at various sites and in various orientations on the pristine arsenene (p-As) surface. Both molecules show chemisorption and the crystal orbital Hamiltonian population (COHP) analysis reveals the formation of strong X-As bonds. In particular, the adsorbed molecules spontaneously dissociate into atomic halogen atoms, with a diffusion barrier of 1.91 (1.72) eV for F2(Cl2). The adsorbed X2 molecules induced distortions in the local geometry due to strong interaction with arsenene. Importantly, the formation of X-As bonding remarkably changed the electronic properties, evidenced by the decrease of the actual band gap due to the emergence of defect states within the band gap. For instance, the F2 adsorbed arsenene system (F2-As) exhibited an average band gap of 1.17 eV, and Cl2 adsorbed arsenene (Cl2-As) showed an average band gap of 0.83 eV. In particular, indirect to direct band gap transition was observed for some adsorption configurations. The reduction in band gap resulted in the enhancement of electrical conductivity. These findings suggest that the electronic properties of arsenene can be tuned by halogen decoration.

Flexible sandwich-structured silver nanowire/exfoliated graphite platelet/aramid nanofiber composite films with excellent EMI shielding, thermal conduction and Joule heating performances

Multifunctional flexible sandwich-structured EMI shielding silver nanowire/exfoliated graphite platelet/aramid nanofiber (AgNW/EGP/ANF) composite films with excellent thermal conduction and Joule heating abilities were successfully prepared by a layer-by-layer vacuum filtration technique. The construction of EGP/ANF layer on the two sides is crucial in achieving outstanding thermal conductivity (TC) and contributes partial EMI shielding effectiveness (SE) for the composite films. The introduction of an ultrathin, dense, and sintered AgNW/ANF layer endows the composite films with significant enhancements in electrical conductivity and EMI SE. As a result, the optimal 30 μm-thick composite films with an AgNW loading of 35 wt% exhibit excellent EMI SE values of 69.0 dB in the X-band and 78.4 dB in the Ka-band and a superior in-plane TC of 48.7 W m−1 K−1. Besides, the prepared composite films present an outstanding Joule heating performance. Briefly, the sandwich-structured composite films show huge potential in advanced portable and wearable electronic applications.

Graphene Oxide‐Incorporated Polylactic Acid/Polyamidoamine Dendrimer Electroconductive Nanocomposite as a Promising Scaffold for Guided Tissue Regeneration

AbstractIn the recent years, electroconductive scaffolds have shown promising capabilities in guided regeneration of electroactive tissues including nerve, heart muscle, bone, cartilage, and skin. Herein, the fabrication of a novel electroconductive poly (L‐lactic acid) (PLLA)/polyamidoamine (PAMAM) dendrimer nanofibrous scaffold containing graphene oxide (GO) nanosheets is described. The presence of PAMAM with amine terminal groups successfully aminolyzed PLLA. Interestingly, both PAMAM (5% w/w) and GO (0.5, 1, 2% w/w) not only contributed to reducing the fiber diameter, increasing the hydrophilicity and degradation rate, but also provided a nanocomposite scaffold with enhancement in electrical conductivity. By incorporating 1% w/w of GO, the nanocomposite scaffold exhibited optimized properties, including electrical conductivity (≈3.09 × 10−5 S m−1), crystallinity (≈ 47%), Young's modulus (≈16.95 MPa), as well as strength (≈1.58 MPa). This nanocomposite also demonstrated significant antibacterial activity of ≥ 90% against both gram‐positive and gram‐negative bacteria. Cellular assays confirmed acceptable cytocompatibility of the nanocomposite scaffolds containing GO and PAMAM, which can support the viability and proliferation of PC‐12 cells. In conclusion, the presence of GO nanosheets alongside PAMAM dendrimers can synergically promote the properties of the prepared nanofibrous mats which can be used as potential electroconductive scaffolds for guided tissue regeneration.

Enhancement of electrical conductivity and band gap of epoxy/MWCNT/GNP/glass fibers hybrid materials

Polymer composites containing carbon nanoparticles have attracted considerable attention because of their special functional characteristics. Characterization of optical and dielectric characteristics was done. To comprehend the impact of nanofillers, dielectric characteristics, UV–Vis spectroscopy, XRD, and Fourier transform spectroscopy were employed. The role of carbon fillers on metrics, such as band gap energy, absorption coefficient, and dielectric characteristics of nanocomposites was examined to differentiate between the effects of nanofillers. The AC conductivity is explained following the classical percolation theory. The percolation threshold is discovered to be 1 wt.% of a hybrid system of nanofillers consisting of graphene nanoplatelets (GNPs) and multi-walled carbon nanotubes (MWCNTs). The presence of carbon nanofillers significantly enhances the electrical conductivity of the nanocomposites. The optical band gap energy of nanocomposites was obtained from the Tauc method. The study establishes the relationship between band gap energy and AC conductivity using Tauc’s relation and Jonscher’s power law. The results show that the band gap energy of composites decreases with the addition of hybrid nanofillers, with values observed at 2.65 eV and 2.95 eV, while without fillers of 3.1 eV and 3.05 eV attributed to increased localized states within the bandgap. Composites with nanofillers show an AC conductivity of 1.86 S/m at 1 wt% of nanofillers, compared to 1.52 × 10−6 S/m and 1.09 × 10−6 S/m for composites without nanofillers. The UV–Vis spectra reveal a significant blue shift in the absorption peak when the weight percentage of carbon nanoparticles is increased. The findings of this study point toward the possibilities of the development of novel nanocomposites with enhanced performance for electronics and energy storage.

Examining the varied localization of oxygen groups on graphene nanosheets and their entangled influence on electromagnetic waves’ absorption within polymeric coatings

In this study, two distinct graphene nanosheets, featuring varying localization of oxygen groups, were synthesized to investigate their influence on the electromagnetic waves’ absorption properties of polymeric coatings. Natural graphite flakes and expanded graphite served as carbon precursors for synthesizing Edge-Functionalized Graphene Oxide (E-GO) and Basal-Functionalized Graphene Oxide (B-GO) nanosheets, respectively. Subsequently, polymer nanocomposite coatings were fabricated by dispersing E-GO and B-GO into a waterborne epoxy matrix. The dielectric properties of these coatings were measured post-in-situ thermal reduction at 225 °C. Results revealed that coatings containing B-GO nanosheets exhibited higher dielectric values compared to those with E-GO nanosheets. Furthermore, the electromagnetic properties of the coatings were examined to correlate the network formation findings obtained from dielectric studies and reflection loss values. It was demonstrated that an improved dispersion state of graphene nanosheets resulted in enhanced interphase formation between epoxy and graphene nanosheets, thereby improving interfacial polarization and dielectric permittivity values. Additionally, residual oxygen groups situated on the graphene basal plane induced dipolar polarization, consequently enhancing the reflection loss values of electromagnetic waves. Ultimately, the enhancements in electrical conductivity and dielectric permittivity contributed to reflection loss values reaching −52.67 dB in coatings with a thickness of 320 μm and a graphene loading level of 1.5 wt%, representing significant advancements compared to existing literature.

Double Percolation of Poly(lactic acid)/Low-Density Polyethylene/Carbon Nanotube (PLA/LDPE/CNT) Composites for Force-Sensor Application: Impact of Preferential Localization and Mixing Sequence.

This study explores the enhancement of electrical conductivity in polymer composites by incorporating carbon nanotubes (CNTs) into a co-continuous poly(lactic acid)/low-density polyethylene (PLA/LDPE) blend, creating a double percolation structure. Theoretical thermodynamic predictions indicate that CNTs preferentially localize in the LDPE phase. The percolation threshold of CNTs in the PLA/LDPE/CNT composites was 0.208 vol% (5.56 wt%), an 80% reduction compared to the LDPE/CNT composite, due to the double percolation structure. This thermodynamic migration of CNTs from PLA to LDPE significantly enhanced conductivity, achieving a 13.8-fold increase at a 7.5 wt% CNT loading compared to the LDPE/CNT composite. The localization of CNTs was driven by thermodynamic, kinetic, and rheological factors, with viscosity differences between PLA and LDPE causing dense CNT aggregation in LDPE. Initial contact of CNTs with PLA reduced aggregation, allowing PLA to infiltrate CNT aggregates during melt-mixing, which influenced the final morphology and electrical conductivity. These findings provide new insights into the fabrication of conductive polymer composites for force sensor applications.