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Conductive polymer composites (CPC) are gaining increasing popularity due to their unique characteristics, which include light weight and the ability to conduct electricity. In this work, CPC were prepared by blending the polylactic acid (PLA) with a conductive filler, graphene nanoplatelets (GNP), at dosages ranging from 1 to 12 wt % using an internal mixer. The hot press machine was used to compress the CPC into thin sheet, and subsequently characterized for tensile, thermal, and electrical properties. The results showed that the addition of GNP at 7 wt % (percolation threshold) successfully transformed the PLA into an electrically conductive material. The tensile modulus increased with added GNP, but elongation at break and tensile strength exhibited an opposite trend. The incorporation of GNP also enhanced the composite's thermal stability. [ABSTRACT FROM AUTHOR]

To resist the plastic deformation of polymer particles during hot press molding, high molecular weights, and moduli are required for composites with segregated structures, thus the prepared composites exhibit poor flexibility. Also, larger particle sizes can bring lower percolation thresholds while the ensuing greater deformation destroys the conductive network. Moreover, segregated composites still face preparation complexities. Herein, a facile method for developing flexible composites with large‐size segregated structures is proposed. First, silver‐coated polydopamine‐modified reduced graphene oxide (Ag@PrGO), as conductive fillers, is prepared by electroless plating. Next, polydimethylsiloxane (PDMS)‐coated polyolefin elastomer (POE) beads are put into a bag containing the fillers. After a simple shaking, the fillers are adhered to the POE surface as the cohesive property of cured PDMS. Finally, flexible composites with large‐size segregated structures are obtained via hot pressing. Benefiting from the 2D structure of the Ag@PrGO and the ability to slip, the conductive networks possess adaptable deformability. The prepared composites exhibit excellent electrical conductivity (203.55 S cm−1) at filler volume fractions of 3.4 vol%. The EMI shielding effectiveness can reach 70 dB in the X‐band at a thickness of 1.9 mm and remains stable after bending and rubbing damage. This work paves the way for constructing large‐size segregated structures. [ABSTRACT FROM AUTHOR]

Conductive polymer composites (CPCs) with nanocarbon fillers are at the high end of modern materials science, advancing current electronic applications. Herein, we establish the interplay between the chemistry and electrophysical properties of reduced graphene oxide (rGO), separately and as a filler for CPCs with the segregated structure conferred by the chemical composition of the initial graphene oxide (GO). A set of experimental methods, namely X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy, van der Paw and temperature-dependent sheet resistance measurements, along with dielectric spectroscopy, are employed to thoroughly examine the derived materials. The alterations in the composition of oxygen groups along with their beneficial effect on nitrogen doping upon GO reduction by hydrazine are tracked with the help of XPS. The slight defectiveness of the graphene network is found to boost the conductivity of the material due to facilitating the impact of the nitrogen lone-pair electrons in charge transport. In turn, a sharp drop in material conductivity is indicated upon further disruption of the π-conjugated network, predominantly governing the charge transport. Particularly, the transition from the Mott variable hopping transport mechanism to the Efros–Shklovsky one is signified. Finally, the impact of rGO chemistry and physics on the electrophysical properties of CPCs with the segregated structure is evaluated. Taken together, our results give a hint at how GO chemistry manifests the properties of rGO and the CPC derived from it, offering compelling opportunities for their practical applications. [ABSTRACT FROM AUTHOR]

Microinjection molding (μIM) is characterized by high shearing and cooling rates, resulting in higher a degree of filler orientation which impairs the electrical conductivity (σ) of conductive filler‐containing polymer composites when compared with that of compression molding and conventional injection molding processes. In this study, polypropylene/polyamide 6/multiwalled carbon nanotubes (PP/PA6/CNT) composites were used as the model system to investigate how blending sequence, injection speed, and component mass ratios affected the morphology and σ of PP/PA6/CNT microparts. The results demonstrated that CNTs exhibited a higher affinity for the polar PA6 phase and they tended to be preferentially distributed in PA6 domains. The deformation and coalescence of CNT‐rich PA6 phase promoted the creation of an intact and continuous filler network structure along the flow direction under the influence of high shearing conditions in μIM. When the mass ratio of PP:PA6 was 70:30 and the concentration of CNT was 7 wt%, the micropart possessed the highest σ (1.2 × 10−6 S/m) when compared with their PP/CNT (4.4 × 10−9 S/m) and PA6/CNT (3.4 × 10−10 S/m) counterparts. Higher injection speeds resulted in higher degree of CNT orientation, which negatively affected the σ of subsequent moldings. This work established an approach for producing electrically conductive microparts that demonstrate promising applications in the fields of electronics, automotive, and microsystems among others. Highlights: PP/PA6/CNT composites were used as model systems for microinjection molding.The electrical conductivity was improved by shear‐induced deformation of CNT‐rich phase.The properties of PP/PA6/CNT microparts were affected by process parameters. [ABSTRACT FROM AUTHOR]

The enhancement of the electromagnetic interference shielding efficiency (EMI SE) for conductive polymer composites (CPCs) has garnered increasing attention. The shielding performance is influenced by conductivity, which is dependent on the establishment of effective conductive pathways. In this review, Schelkunoff's theory on outlining the mechanism of electromagnetic interference shielding was briefly described. Based on the mechanism, factors that influenced the electrical percolation threshold of CPCs were presented and three main kinds of efficient methods were discussed for establishing conductive pathways. Furthermore, examples were explored that highlighted the critical importance of such conductive pathways in attaining optimal shielding performance. Finally, we outlined the prospects for the future direction for advancing CPCs towards a balance of enhanced EMI SE and cost–performance. [ABSTRACT FROM AUTHOR]

Elastic polymer-based conductive composites (EPCCs) are of great potential in the field of flexible sensors due to the advantages of designable functionality and thermal and chemical stability. As one of the popular choices for sensor electrodes and sensitive materials, considerable progress in EPCCs used in sensors has been made in recent years. In this review, we introduce the types and the conductive mechanisms of EPCCs. Furthermore, the recent advances in the application of EPCCs to sensors are also summarized. This review will provide guidance for the design and optimization of EPCCs and offer more possibilities for the development and application of flexible sensors. [ABSTRACT FROM AUTHOR]

Printed conductive polymer composites allow for the bespoke manufacture of products with complicated geometries, which is critical for rapid prototyping and adaptability of flexible electrical devices. However, it is still challenging to prepare environmentally friendly and sustainable conductive polymer composites with aqueous solvent systems which accomplish excellent printing and electromechanical properties at the same time. In this work, the effect of composite components on performance was explored, and orthogonal tests were utilized to discover the precise formulation of new green aqueous conductive polymer composites with superior performance. The printing accuracy of the conductive polymer composites was enhanced (printed circuit burrs less than 20 μm) and the dependability of the printed circuits as well as the failure mechanism during electrochemical migration (ECM) were thoroughly investigated. As a proof of concept, ultrahigh frequency (UHF) flexible linearly polarized antennae with read range forward surpassing 10 m was designed and printed. [ABSTRACT FROM AUTHOR]

Twisted string actuators (TSAs) are innovative linear soft actuators that can mimic natural muscle contraction. However, obtaining feedback on their stroke requires cumbersome external sensors that compromise their compliance. We addressed this by developing self-sensing strings using conductive polymer composites (CPCs). The CPC strings exhibit electrical resistance changes in response to strain, enabling stroke sensing by the strings themselves. We fabricated CPCs strings with varying concentrations of multi-walled carbon nanotubes (MWCNTs). Characterization revealed excellent conductivity, tensile strength exceeding 30 N, tunable strain sensitivity via MWCNTs concentration variation, as well as stable and repeatable strain-dependent resistance changes. Optimization via a high-strength core fiber enabled the CPCs strings to withstand over 6kg loading with enhanced stroke and minimal resistance variation. We achieved at least a 97.8% linear correlation between resistance change rate and contraction rate in twisting experiments. This research provides a self-contained stroke sensor compatible with high-load soft TSAs, overcoming limitations of external sensors. The simple yet effective sensing mechanism could spur adoption of TSA in robotics. [ABSTRACT FROM AUTHOR]

The colossal development of modern electronic devices has inevitably led to an increase in electromagnetic interference (EMI), which has gradually become the fourth most prevalent type of pollution in the world. It is therefore necessary to seek more effective EMI‐shielding materials to overcome the shortcomings of conventional metal‐based materials, which include high density, a lack of mechanical flexibility, low corrosion resistance and costly processing. Conductive polymer composites (CPCs) have attracted more and more attention due to their superiority in many aspects. However, their performances should be further enhanced for future applications. One polymer with only one type of filler often cannot meet this kind of requirement. In this paper, filled polymer materials for EMI shielding are reviewed in terms of their processing, rheological properties, conductivity, and shielding effectiveness. Moreover, the combination of different ingredients and fillers when fabricating multicomponent composites for EMI shielding is also highlighted. The coordination of various components in composites with different structures, including solid, segregated, layered/sandwiched, and foamed/porous structures, is then discussed. [ABSTRACT FROM AUTHOR]

Conductive polymer composites (CPCs) with the ability to maintain high conductivity whilst remaining flexible at various operating temperatures and conditions have gained interest as potential materials for electronic interconnect applications. The ability of a polymer matrix to conduct electricity is mainly dependent on the conductive filler loadings as well as the formation of network paths within the CPCs. The main aim of this research work was to establish and understand the correlation between the network structure formation and mechanical properties of linear low-density polyethylene/copper (LLDPE/Cu) and liquid silicone rubber/copper (LSR/Cu) CPCs. Various techniques such as electron microscopy, thermal studies, four-point probe, and tensile testing were employed in this study. Furthermore, selected samples were characterized and tested using synchrotron micro-x-ray fluorescence (XRF) technique and dynamic mechanical analysis (DMA). It was found that the electrical conductivity of the CPCs increased with increasing filler loadings. Addition of Cu filler had a marginal effect on the tensile strength of both LLDPE/Cu and LSR/Cu CPCs. Nevertheless, it was found that the elongation at break for LLDPE/Cu consistently increased with the addition of Cu whereas, for LSR/Cu samples, the elongation at break decreased with the addition of Cu at various loadings. The scanning electron microscopy (SEM) micrographs obtained show that the particles of Cu were closer to one another at higher filler loadings. The data obtained revealed the potential for utilizing CPCs as flexible interconnects suitable for advanced electronic applications. [ABSTRACT FROM AUTHOR]

Nanocomposites based on an immiscible blend of polyamide 6 (PA6) and polyamide 12 (PA12) 50/50 wt.% with different contents of multi‐walled carbon nanotubes (MWCNTs) were prepared by extrusion followed by compression molding. These materials have been proved to be electrically conductive in previous investigations for the range of filler content assayed. The morphology of the nanocomposites was analyzed using scanning electron microscopy, both on cryo‐fractured and postmortem uniaxial tensile samples. Rheological measurements were performed along with differential scanning calorimetry, to assess the materials microstructure and thermal transitions. Furthermore, uniaxial tensile tests were carried out to determine mechanical properties such as stiffness, strength, and strain at break and to investigate the effect of MWCNTs on these properties. Finally, fracture tests were also conducted to evaluate how incorporating MWCNTs affected nanocomposites toughening capabilities. The obtained results suggest a notable improvement in the mechanical properties in the nanocomposites with low amounts of nanofiller. This expands their potential applications as conductive polymer composites (CPCs) and positions them as promising multifunctional materials. Highlights: CPCs based on a PA blend and MWCNTs were successfully obtained.CNTs strongly affected the blend morphology and rheological properties.CNTs significantly modified the crystallization behavior of PA6.Ductility greatly improved at low CNT contents but decreased at high loadings.Stiffness increased steadily with increasing CNT content. [ABSTRACT FROM AUTHOR]

Highlights The paper introduces a bioresorbable elastomer, poly(glycolide-co-ε-caprolactone) (PGCL), with remarkable mechanical properties, including high elongation-at-break (

Four-dimensional (4D) printing technology is an innovative concept integrating conventional 3D printing additive manufacturing (AM) and smart materials programed to change properties or shape over time in response to environmental stimuli. This study aims to characterize the strength and electrical resistance of a commercial electrically conductive polylactic acid (PLA) with carbon black (CB) particles printed by fused filament fabrication (FFF) technique to evaluate the development feasibility of two sensor prototypes: (1) a load-cell sensor, and (2) a temperature sensor. Experiments were performed to study the orientation and raster angle–dependent mechanical and electrical performance of a PLA-CB conductive polymer manufactured by AM-FFF technology. A good agreement was observed between the data received from the manufacturer and the experimental density of the conductive AM-FFF PLA-CB three-point bending samples. The mechanical properties of 3D-printed PLA-CB were characterized based on three-point bending flexural test. Two build orientations (flat and upright) and three raster patterns (0°/90°, +45°/-45°, and concentric) were printed to check the optimal mechanical properties for electrical conductivity; six samples were printed for each one of the six configurations. The three-point bending flexural test results of the examined 36 specimens demonstrated that the samples printed in the concentric and +45°/-45° raster patterns exhibit the best mechanical properties, with the highest flexural strength and flexural modulus of elasticity in the flat orientation. Nevertheless, the concentric pattern has an advantage over the +45°/-45° pattern due to higher density and homogeneity. To examine the electrical resistance of the PLA-CB material another 12 specimens were printed and divided into four groups, each with different lengths. The electrical intrinsic resistivity was calculated from the geometry of the specimens and the measured resistance, with an average value of 13.2 [Ω·cm]. To check the production feasibility of a load-cell sensor prototype the effect of load on electrical conductivity was examined, however no effect of load on resistance was discovered. To prove the production feasibility of a sensor prototype for temperature measurements a preliminary device was designed and the effect of increasing and decreasing the temperature between 24 and 42°C on electrical resistance was examined. Based on the experimental results a calibration function was built linking between the temperature and the material’s resistance.

Wearable and stretchable strain sensors have potential values in the fields of human motion and health monitoring, flexible electronics, and soft robotic skin. The wearable and stretchable strain sensors can be directly attached to human skin, providing visualized detection for human motions and personal healthcare. Conductive polymer composites (CPC) composed of conductive fillers and flexible polymers have the advantages of high stretchability, good flexibility, superior durability, which can be used to prepare flexible strain sensors with large working strain and outstanding sensitivity. This review has put forward a comprehensive summary on the fabrication methods, advanced mechanisms and strain sensing abilities of CPC strain sensors reported in recent years, especially the sensors with superior performance. Finally, the structural design, bionic function, integration technology and further application of CPC strain sensors are prospected.

Conductive polymer composites (CPCs) with nanocarbon fillers are at the high end of modern materials science, advancing current electronic applications. Herein, we establish the interplay between the chemistry and electrophysical properties of reduced graphene oxide (rGO), separately and as a filler for CPCs with the segregated structure conferred by the chemical composition of the initial graphene oxide (GO). A set of experimental methods, namely X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy, van der Paw and temperature-dependent sheet resistance measurements, along with dielectric spectroscopy, are employed to thoroughly examine the derived materials. The alterations in the composition of oxygen groups along with their beneficial effect on nitrogen doping upon GO reduction by hydrazine are tracked with the help of XPS. The slight defectiveness of the graphene network is found to boost the conductivity of the material due to facilitating the impact of the nitrogen lone-pair electrons in charge transport. In turn, a sharp drop in material conductivity is indicated upon further disruption of the π-conjugated network, predominantly governing the charge transport. Particularly, the transition from the Mott variable hopping transport mechanism to the Efros–Shklovsky one is signified. Finally, the impact of rGO chemistry and physics on the electrophysical properties of CPCs with the segregated structure is evaluated. Taken together, our results give a hint at how GO chemistry manifests the properties of rGO and the CPC derived from it, offering compelling opportunities for their practical applications.

The enhancement of the electromagnetic interference shielding efficiency (EMI SE) for conductive polymer composites (CPCs) has garnered increasing attention. The shielding performance is influenced by conductivity, which is dependent on the establishment of effective conductive pathways. In this review, Schelkunoff’s theory on outlining the mechanism of electromagnetic interference shielding was briefly described. Based on the mechanism, factors that influenced the electrical percolation threshold of CPCs were presented and three main kinds of efficient methods were discussed for establishing conductive pathways. Furthermore, examples were explored that highlighted the critical importance of such conductive pathways in attaining optimal shielding performance. Finally, we outlined the prospects for the future direction for advancing CPCs towards a balance of enhanced EMI SE and cost–performance.

Highlights: The paper introduces a bioresorbable elastomer, poly(glycolide-co-ε-caprolactone) (PGCL), with remarkable mechanical properties, including high elongation-at-break (< 1300%), resilience, and toughness (75 MJ m−3) for soft and transient electronics. Fabrication of conducting polymers with PGCL yields stretchable, conductive composites for transient electronic devices, functioning reliably under external strains. The study demonstrates the feasibility of a disintegrable electronic suture system with on-demand drug delivery for rapid recovery of post-surgical wounds on soft, time-dynamic tissues or versatile biomedical areas of interest. Substrates or encapsulants in soft and stretchable formats are key components for transient, bioresorbable electronic systems; however, elastomeric polymers with desired mechanical and biochemical properties are very limited compared to non-transient counterparts. Here, we introduce a bioresorbable elastomer, poly(glycolide-co-ε-caprolactone) (PGCL), that contains excellent material properties including high elongation-at-break (< 1300%), resilience and toughness, and tunable dissolution behaviors. Exploitation of PGCLs as polymer matrices, in combination with conducing polymers, yields stretchable, conductive composites for degradable interconnects, sensors, and actuators, which can reliably function under external strains. Integration of device components with wireless modules demonstrates elastic, transient electronic suture system with on-demand drug delivery for rapid recovery of post-surgical wounds in soft, time-dynamic tissues. [ABSTRACT FROM AUTHOR]

Polymer-carbon composite bipolar plates (PCCBP) are accepted over graphite bipolar plates (BP) for their use in proton exchange membrane fuel cell (PEMFC), specially in hydrogen fuel cell-powered electric vehicles. This study developed a novel copper fiber-filled PCCBP with epoxy resin as the binder and natural flake graphite (NFG), carbon black (CB), and Cu fiber as filler materials. The fabrication is done by compression molding. Both electrical conductivity and flexural strength increased with the addition of Cu fiber. The composite BP fabricated with 8 vol % Cu fiber, 10 vol % CB, and 42 vol % NFG exhibited electrical conductivity of 169 S/cm, flexural strength of 43 MPa, thermal conductivity of 17 W m−1 K−1 and corrosion current density of 0.972 μA/cm2. The composite also showed acceptable results for contact angle, density and thermal stability tests. This research paper provides insights into further developments of the metal-based PCCBP. • Novel Cu fiber-filled composite bipolar plates were developed for PEM fuel cells. • Effect of content of epoxy resin, carbon black, and copper fiber was investigated. • Enhancement of electrical conductivity and flexural strength achieved concurrently. • Provides insights into future developments of the metal-based PCCBP. [ABSTRACT FROM AUTHOR]

Polymer composites with high dielectric constant and minimal dielectric losses have wide ranging prospects for advanced applications in the flexible electronics and electrical industry. In this study, we used the advantages of carbonaceous hybrid nanofillers to develop a flexible dielectric material. Herein, a set of hybrid nanocomposites were successfully fabricated by incorporating the Ti3C2Tx (MXene) and MWCNTs (multi‐walled carbon nanotubes) hybrid mixture as the conductive moiety into the poly(ethylene‐co‐methyl acrylate) (EMA)/ethylene‐octene co‐polymer (EOC) binary blend as the matrices using solution mixing technique followed by compression molding. As prepared, EMA/EOC/Ti3C2Tx/MWCNTs hybrid composites have been characterized by FTIR (Fourier transform infrared) spectroscopy, XRD (X‐ray diffraction), TGA (thermogravimetric analysis), FESEM (field emission scanning electron microscopy), and DSC (differential scanning calorimetry). We studied the effects of Ti3C2Tx and MWCNTs contents in the hybrid composites on the thermal, dielectric, and electrical properties. Among all the 15 wt% hybrid mixture containing 2 wt% MWCNTs loaded composite has the highest dielectric constant (ℇr = 122.21) and the lowest dissipation loss (tan δ = 0.030) at 100 Hz. The present studies recommend the EMA/EOC/Ti3C2Tx/MWCNTs hybrid composites can be used in smart and flexible electronic storage material. Highlights: EMA‐EOC blend composites with hybrid Ti3C2Tx/MWCNTs were processed.2.5 wt% MWCNTs loaded hybrid composite shows excellent thermal stability.Composite with 2 wt% MWCNTs has ℇ' = 122.21 and tanδ = 0.03 at 100 Hz.2.5 wt% MWCNTs composite has electrical conductivity of 3.26 × 10−8 Ω−1 m−1.This composite can be used in smart and flexible electronic storage material. [ABSTRACT FROM AUTHOR]

In order to prepare a flexible strain sensor with a large monitoring range, high sensitivity and excellent stability, a polyolefin elastomer (POE)/carbon nanotubes (CNTs) conductive polymer composite with a bilayer structure was prepared by biaxially stretching in this work. The results showed that the bilayer structured nanocomposites had better processability and better stability than monolayer CNT/POE nanocomposites during biaxial stretching. The biaxial stretching process could promote the dispersion and planar orientation of CNTs within the polymer, improving the crystallinity of nanocomposites and the sensing performance of strain sensors. The optimal stretching ratios (SRs) of bilayer structured nanocomposites were studied. The 8 wt% CNT/POE‐POE strain sensor with an SR of 2.5 exhibited a high sensitivity (gauge factor/GF = 72604.7 at 900% strain), wide strain range (0%–900%), and stable cycling performance (1000 cycles at 30% strain), showing a broad application prospect in wearable electronic devices. This study provides a valuable method for efficiently manufacturing high performance and low‐cost flexible strain sensors. [ABSTRACT FROM AUTHOR]

In recent decades, flexible and wearable strain sensor has shown promising application prospects in human motion detection, medical rehabilitation, human‐computer interface, etc. Conductive polymer composites (CPCs) composed of conductive fillers and elastic polymers demonstrate the merits of excellent flexibility, high stretchability, and good tensile recovery. They are usually used as flexible strain sensors with large working range and high sensitivity. This review introduces in detail the preparation, morphologies and strain sensing performance of different CPC sensors including one‐dimensional fibers, two‐dimensional films, three‐dimensional foams and hydrogels. CPCs with different structures show their unique advantages in reducing the percolation threshold and/or improving the sensing performance. The multi‐functionalities of CPC strain sensors with extended applications are also reviewed. Finally, we summarize the current challenges and outlook the future development of the CPC strain sensors. [ABSTRACT FROM AUTHOR]

Abstract The colossal development of modern electronic devices has inevitably led to an increase in electromagnetic interference (EMI), which has gradually become the fourth most prevalent type of pollution in the world. It is therefore necessary to seek more effective EMI‐shielding materials to overcome the shortcomings of conventional metal‐based materials, which include high density, a lack of mechanical flexibility, low corrosion resistance and costly processing. Conductive polymer composites (CPCs) have attracted more and more attention due to their superiority in many aspects. However, their performances should be further enhanced for future applications. One polymer with only one type of filler often cannot meet this kind of requirement. In this paper, filled polymer materials for EMI shielding are reviewed in terms of their processing, rheological properties, conductivity, and shielding effectiveness. Moreover, the combination of different ingredients and fillers when fabricating multicomponent composites for EMI shielding is also highlighted. The coordination of various components in composites with different structures, including solid, segregated, layered/sandwiched, and foamed/porous structures, is then discussed.

[Display omitted] Expanded graphite–polyimide composites for fuel cells containing from 0 to 23 wt% expanded graphite were produced by direct compression molding after pre-mixing the binder and filler. The percolation threshold in this system was determined to be 2.5%, while the corrosion current was 3 × 10−2 μA cm−2, and the composites were thermally stable up to 400 °C. [ABSTRACT FROM AUTHOR]

Elastic polymer-based conductive composites (EPCCs) are of great potential in the field of flexible sensors due to the advantages of designable functionality and thermal and chemical stability. As one of the popular choices for sensor electrodes and sensitive materials, considerable progress in EPCCs used in sensors has been made in recent years. In this review, we introduce the types and the conductive mechanisms of EPCCs. Furthermore, the recent advances in the application of EPCCs to sensors are also summarized. This review will provide guidance for the design and optimization of EPCCs and offer more possibilities for the development and application of flexible sensors.

The requirement for a lightweight bipolar plate (BP) for Proton Exchange Membrane Fuel Cell (PEMFC) is increasing to make it feasible to power hydrogen fuel cell electric vehicles. Composite BP with carbon materials as conductive fillers and polymer as the binder are preferable over pure graphite and metallic BP. This study investigates the effect of Surface‐enhanced flake graphite (SEFG) as a novel filler material in composite BP. A composite BP is developed with Epoxy Resin (ER) as the binder and Natural Flake Graphite (NFG), Carbon Black (CB) and SEFG as conductive fillers. Composite BP fabricated with 10 vol% SEFG, 10 vol% CB, and 40 vol% NFG exhibited an electrical conductivity of 158 S cm−1, flexural strength of 38 MPa, water contact angle of 90.410 and corrosion current density of 0.261 μA cm−2. The composite BP also achieved a density of 1.55 g cm−3, water absorption of 0.6% and thermal conductivity of 3.6 W m−1 K−1 at 120°C. These results are highly favorable for BPs used in PEMFC. This paper provides an insight into using surface‐modified conductive carbon filler materials to develop composite BP for application in PEMFC. [ABSTRACT FROM AUTHOR]

The "two‐step" strategy composed of Pickering emulsion method and supercritical batch foaming technology is successfully conducted to prepare the microcellular polycaprolactone (PCL)/cellulose nanocrystal (CNC)/carbon black (CB) conductive composites. Benefitting from the segregated CNC/CB networks established in the PCL matrix, the obtained microcellular conductive composites can present improved electrical and mechanical performance, and uniform foam structures. The percolation threshold (φc) is estimated as low as ~0.84 wt%, and the minimum tensile strain and strength belonging to the foamed composite with 10 wt% of CB content still maintain 15% and 3.95 MPa, respectively. This study hopes to provide an attempt to prepare microcellular conductive composites with great comprehensive performance. [ABSTRACT FROM AUTHOR]

Considering the application of conductive polymer composites with segregated structure in electronics and aerospace industries, their mechanical properties becomes important. In this research, High Density Polyethylene (HDPE), Carbon Black (CB) as conductive phase and Low Density Polyethylene (LDPE) were used as reinforcing phase to make composite. Mechanical mixing followed by hot pressing was used to prepare composites. The conductivity of the samples was measured to ensure the formation of segregated structure. In the xCB-HD sample, the maximum electrical conductivity was 43.10 S/m and in the xCB-1LD sample, it was 36.62 S/m. Evaluation of microscopic images also confirms the formation of conductive paths in the structure, and microscopic images also confirmed the results of electrical conductivity. With the increase of the conductive carbon phase at the boundary of the HDPE granules due to the creation of structural defects, the yield strength decreasing trend was observed compared to pure polyethylene.. By increasing the weight percentage of carbon black from 1 to 2 weight percent, yield strength improved by 20 to 40 percent and Young's modulus by 7 to 22 percent in xCB-HD and xCB-1LD segregated structures. [ABSTRACT FROM AUTHOR]

In this study, electrically conductive composites of ethylenedioxythiophene-based terpolymer (PETCH), polyvinylidene difluoride (PVDF) and graphene nanosheets (GNS) have been prepared by compression molding and characterized. A new conjugated PETCH polymer was synthesized and its chemical structure has been confirmed by Fourier transform infrared and 1H-NMR spectroscopy. The varying weight percentages of (1, 3 and 5%) GNS and 10 wt% PETCH dispersed PVDF nanocomposites were prepared and characterized using X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) analysis. The thermal studies indicated that the decomposition occurred at a temperature around 220°C, and 480°C corresponds to the PETCH and PVDF/PETCH/GNS (1, 3 and 5%), respectively. The EDX spectrum of neat PETCH polymer and their composites of PVDF/PETCH/GNS (1, 3 and 5%) result clearly shows the presence of all elements such as, C, O, S, F and Cl with an atomic weight percentage. The PVDF/PETCH/5% GNS has a dielectric constant value of 3.9 at 1 MHz and the conductivity of this polymer composites value is found to be 5.8 × 10–6 S cm–1 at 1 MHz, respectively. Results obtained from the dielectric studies indicated that the GNS and terpolymer-dispersed PVDF composites exhibit good interfacial adhesion as evidenced from conductive behaviours. [ABSTRACT FROM AUTHOR]

The rapid advancement of electronic communication technology has greatly aided human productivity and quality of life, but it has also resulted in significant electromagnetic pollution issues. Traditional metals and alloys are often used for electromagnetic interference (EMI) shielding due to their excellent electrical conductivity. However, they have drawbacks such as being heavy, expensive, and having low corrosion resistance, which limits their application in electromagnetic shielding. Therefore, it is crucial to develop novel EMI shielding materials. Polymers, being highly flexible, corrosion-resistant, and possessing high specific strength, are frequently employed in electromagnetic shielding materials. In this review, we firstly introduce the basic theory of electromagnetic shielding. Then, we outline the processing methods and recent developments of polymer-based electromagnetic shielding composites, including uniform-, foam-, layered-, and segregated structures. Lastly, we present the challenges and prospects for the field, aiming to provide direction and inspiration for the study of polymer-based electromagnetic shielding composite materials. [ABSTRACT FROM AUTHOR]

Conductive polymer composites with segregated structure (s‐CPCs) are widely used in the electronics industry. Achieving selective distribution of the conductive fillers in the polymer matrix is an effective way to construct s‐CPCs. In this work, the starch was used as the matrix and the carbon nanotube (CNT) was used as the conductive fillers to fabricate multifunctional s‐CPCs, via simple mechanical mixing and compression molding. During the processing, the starch underwent partial gelatinization, which was conducive to the fusion of the starch granules and the selective distribution of the CNT. Scanning electron microscope and atomic force microscope images showed that the CNT was attached to the surface of the starch granules to form a segregated structure. The starch/CNT composites exhibited a significant percolation, with a percolation threshold of 0.24 vol%. When the CNT content was 3.05 vol%, the starch/CNT composites exhibited a high electromagnetic interference (EMI) shielding effectiveness of 33.12 dB, which was commercially applicable in EMI shielding devices. The starch/CNT composites also possess good thermal management properties and can be used as thermal conductors and electro‐thermal conversion devices. This work manifests the application prospect in the field of the electronics industry and broadens the application potential of starch. [ABSTRACT FROM AUTHOR]

The magnesium oxide–nickel oxide (MgO–NiO), nickel oxide–cobalt oxide (NiO–CoO), and magnesium oxide–cobalt oxide (MgO–CoO)-based mixed metal oxides (MMO) were synthesized by sol–gel method. The grafting of conductive polymers (CP), namely polyaniline (PANI), polyorthoanisidine (POA), and PANI–POA copolymer, is carried out on synthesized mixed metal oxide (MMO) by using a chemical oxidation method using ammonium persulfate (APS) as oxidizer, and the doping agent is used as hydrochloric acid (HCl) to make the MMO-CP composites. The synthesis of MMO-CP formation was confirmed with the FTIR, XRD, and UV–visible analysis. The epoxy-polyamide coating formulation is reinforced with MMO-CP composites at 4% (w/w) concentration, and the ultrasonication technique is used for uniform dispersion of MMO-CP into the coating formulation. The mild steel is used as a substrate for casting synthesized coating film, and curing is carried out at 90 °C. The mechanical analysis observed that hardness properties and scratch formation resistance are increased by reinforcement of MMO-CP, whereas chemical resistance remained unaffected. The corrosion resistance increased by incorporation of MMO-CP into the coating formulation, and it is evaluated by the salt spray analysis. The NiO–CoO–POA composite-based coating performs excellently in pencil hardness, scratch resistance, and in the salt spray test. [ABSTRACT FROM AUTHOR]

Nowadays, although highly conductive polymer composites filled with two‐dimensional graphene‐based nano‐fillers have been explored extensively, constructing nanocomposites with high performance, industrial feasibility, and more efficient conductive networks at lower nano‐filler contents remains a challenge. To achieve the above objectives, industrial wastes microsilica powder (N98) with amorphous spherical structure and large particle size is employed in this work. And the hybrids (TGN) are obtained between N98 and graphene (GE) by the effective bridging and interface coupling of tannic acid, which can achieve the purpose of obtaining conductive composites with low‐filler contents by traditional polymer processing technologies. The volume exclusion effect of N98 and its own assisted dispersion effect can prevent and attenuate graphene agglomeration, enabling the formation of a dense, complete and uniform conductive network in natural rubber (NR) matrix based on a small amount of graphene addition (parts per thousand). Thus, it give the nanocomposite highly functional, especially electric property. The results show that when the ratio of GE to N98 hybridization is 1:20, N98 and graphene are more uniformly hybridized together, and the volume exclusion effect is best matched with the rubber composites, and the comprehensive performance is optimal. Moreover, the electrical conductivity of NR/TG1N20 nanocomposite can reach the balanced value of 10−3 S·cm−1 with the GE loading of 0.48 phr, which shows the effectiveness of the prepared hybrids. [ABSTRACT FROM AUTHOR]

AbstractIntroduction: Conductive polymer composites (CPCs) have been getting attention in academic and industrial fields for several decades. Unfortunately, ordinary CPCs with random conductive network usually require a high filler percentage to provide desired conductivity. In upcoming research, an electrically conductive polymer composites with segregated structure was used in order to achieve high conductivity at low filler percentagesMethods: Segregated Structure HDPE/CNT nanocomposite were produced with pure nanotubes reinforcement and modified surface nanotubes by dry mixing method.Findings: Microscopic images results showed that in both types of pure and surface modified composites an aggregated arrangement structure was created and carbon nanotubes were placed in interface between the granules. Conductivity results showed an exponentially increase in structure conductivity with increasing carbon nanotube content. The maximum value of conductivity in two composites with pure nanotubes and surface modified nanotubes at 6 wt% respectively was 47.675 , 27.675 s/m. The Maximum shielding (EMI) in raw carbon nanotubes reinforced composite and modified surface respectively was equal to 9 and 9.31 dB.

Abstract Epoxy-based nanocomposites can be ideal electromagnetic interference (EMI)-shielding materials owing to their lightness, chemical inertness, and mechanical durability. However, poor conductivity and brittleness of the epoxy resin are challenges for fast-growing portable and flexible EMI-shielding applications, such as smart wristband, medical cloth, aerospace, and military equipment. In this study, we explored hybrid nanofillers of single-walled carbon nanotubes (SWCNT)/reduced graphene oxide (rGO) as conductive inks and polyester fabrics (PFs) as a substrate for flexible EMI-shielding composites. The highest electrical conductivity and fracture toughness of the SWCNT/rGO/PF/epoxy composites were 30.2 S m−1 and 38.5 MPa m1/2, which are ~ 270 and 65% enhancement over those of the composites without SWCNTs, respectively. Excellent mechanical durability was demonstrated by stable electrical conductivity retention during 1000 cycles of bending test. An EMI-shielding effectiveness of ~ 41 dB in the X-band frequency of 8.2–12.4 GHz with a thickness of 0.6 mm was obtained with an EM absorption-dominant behavior over a 0.7 absorption coefficient. These results are attributed to the hierarchical architecture of the macroscale PF skeleton and nanoscale SWCNT/rGO networks, leading to superior EMI-shielding performance. We believe that this approach provides highly flexible and robust EMI-shielding composites for next-generation wearable electronic devices.

Conductive polymer composites (CPCs) have been identified as viable replacements for graphite and metals for polymer electrolyte membrane fuel cell (PEMFC) bipolar plates (BPs). One important factor, apart from composite formulation, that affects the quality and properties of CPC BPs is the processing route. Therefore, understanding the possible processing methods for different matrix–filler combinations and their effects on the quality and properties of the plates can help in controlling and improving the final performance of BPs. This paper reviews the blending and molding techniques for CPC BPs, with a focus on relationship between formulation and processing method. The effects of processing route and conditions on microstructural features of CPC BPs, which affect the performance of the plates are also discussed. Finally, directions for further studies with potential to advance the development of quality and high‐performance CPC BPs are highlighted. Identified key areas for further research include control of filler orientation to improve through‐plane conductivity, correlation between processing parameters and dimensional accuracy of molded plates, and additive manufacturing of composite BPs. [ABSTRACT FROM AUTHOR]

Flexible strain sensors are one of the core devices in wearable electronics. At present, it is still difficult to develop flexible strain sensors with high stretchability, sensitivity, and long‐term stability. In this study, polyaniline (PANI) is successfully coated onto the surface of epoxidized natural rubber (ENR) nanospheres to form the PANI@ENR composites with core–shell structure by in situ polymerization. At PANI content of 5 wt% (PANI/ENR), the optimally conductive networks of PANI endow the composites with excellent comprehensive properties. The strain‐sensing tests show that the PANI@ENR composites possess two successive linear sensing ranges (gauge factor of 7.3 in 0–400% strain, gauge factor of 1.8 in 400–1000% strain) and excellent cycling stability (over 2500 cycles at 0–50% strain). In addition, PANI@ENR‐based strain sensors can monitor the movements of human finger joints, elbow joints, and knee joints in real time, indicating a wide range of potential applications in wearable flexible electronics. [ABSTRACT FROM AUTHOR]

ABSTRACTSmart structures have the advantages of high system integrity and diverse sensing capabilities. However, the labor-intensive and time-consuming fabrication process hinders the large-scale adoption of smart structures. Despite recent attempts to develop sensor-embedded structures using 3D printing technologies, the reported smart structures generally suffer from the complex fabrication process, constrained part size, and limited sensing modality. Herein, we propose a workflow to design and fabricate novel smart structures via multimaterial fused deposition modeling (FDM)-based 3D printing. More specifically, conductive filaments with tailorable mechanical and electrical properties, e.g. piezoresistive effects, were developed. Additionally, the printing process was optimized for processing soft filaments with Young’s modulus around 2 MPa, resolving the issue of filament buckling. Furthermore, the potential applications of the proposed workflow were showcased using three design cases, i.e. biaxial strain sensor, smart tire, and cable-driven soft finger with multiple sensing capabilities. This workflow provides a cost-effective and rapid solution for developing novel smart structures with soft materials.

Conductive polymer composites (CPCs) have demonstrated significant potential in the aerospace, electronics, and communications industries. In this study, polypropylene (PP)/multiwalled carbon nanotubes (MWCNTs) binary composites and in situ fiber reinforced multicomposites made from PP/MWCNTs were fabricated by microcellular injection molding. In addition to crystallization behavior, foam morphology, mechanical properties, dielectric properties, and electromagnetic shielding properties of the composites were analyzed. According to the results, microporous structures can facilitate the distribution of conductive fillers, thereby enhancing the electromagnetic shielding performance and mechanical properties of the composite. In situ microfiber networks display a heterogeneous nucleation effect, resulting in an increase in foam density, which improves composite performance. In situ fiber‐reinforced microporous multicomposites are capable of exhibiting higher elongation at break and electromagnetic shielding properties than binary systems, and the multicomposites can achieve greater electromagnetic shielding effectiveness (SE) with fewer conductive fillers. Ultimately, fiber‐reinforced microporous composites with an elongation at break of 194.40%, an electromagnetic shielding effect of >20 dB, and an absorption mechanism are produced. A feasible method is presented in this study for preparing CPCs that produce light weight, excellent mechanical properties, and high electromagnetic SE at low filler levels. [ABSTRACT FROM AUTHOR]

Constructing the microcellular structure in the conductive polymer composites (CPCs) is a promising approach to improve the sensitivity and durability of the piezoresistive sensor. Selectively placing the conductive fillers, to form the segregated network between the polymer region, can effectively improve the electric performance of CPCs. However, few researches have focused on the influence of the polymer bead size on the segregated network and the large‐scale production of spherical polymer beads with low cost is still difficult to realize. Herein, plenty of regular‐shaped poly(butylene adipate‐co‐terephthalate) (PBAT) beads were manufactured through underwater pelletizing process, which was further coated with carbon nanotube (CNT) particles with the assistance of ball milling technology, and eventually the sensor was successfully fabricated through supercritical carbon dioxide (scCO2) bead foaming technology. The lightweight and flexible sensor exhibited the uniform cell structure with the mean cell size of 51.0 μm and cell density of 3.9 × 108 cells/cm3 when the pelletizing cutter speed was 2500 rpm and the foaming temperature was 117.5°C. And the conductivity of the sensor reached 6.5 S/m incorporated with 3 wt% CNT, which possessed high sensitivity, good stability and long‐term durability, attributed to its excellent microcellular structure and segregated conductive network. [ABSTRACT FROM AUTHOR]

Herein, a comparative study for the effect of nanoparticle networks on rheological behavior, electrical conductivity, and electromagnetic wave (EMW) shielding effectiveness (SE) is carried in conductive polymer composites (CPC). Two different polymers, that is, poly(ε‐caprolactone) (PCL) and isotactic polypropylene (iPP), which have different dispersion of multiwall carbon nanotubes (MWCNT), are used as polymer matrices. A transmission electron microscope (TEM) and a scanning electron microscope (SEM) are employed to determine the dispersion of MWCNTs in different polymer matrices. A rotational rheometer and a vector network analyzer are used to evaluate the percolation thresholds of storage modulus, complex viscosity and EMW SE, respectively. The results indicate that the EMW SE percolation thresholds are much larger than the electrical and rheological percolation thresholds. Specifically, the percolation thresholds of storage modulus and complex viscosity are 0.39 and 0.33 vol% for the MWCNT/PCL samples, and 1.57 and 1.57 vol% for the MWCNT/iPP samples, respectively. The electrical and EMW SE percolation thresholds are 0.33 and 1.99 vol%, 1.24 and 5.41 vol% for the MWCNT/PCL and MWCNT/iPP nanocomposites, respectively. The electrical and rheological percolation may happen in the samples with a sparse MWCNT network, while EMW SE percolation may require a dense MWCNT network in the samples. [ABSTRACT FROM AUTHOR]

We have developed conductive, lightweight, and porous composite of polyvinylidene difluoride by blending with synthesized conjugated terpolymer and graphene for conductive polymer composite applications. The new conjugated terpolymer designated as PEPy-TP is synthesized from 3,4-ethylenedioxythiophene, 1-pyrenecarboxzaldehyde, and heptaldehyde through friedel craft reaction. The synthesized terpolymer PEPy-TP have been blended with polyvinylidene difluoride and graphene nanosheets to form porous composite and has been characterized using XRD, TGA, TG-DSC, DTA, DTG, SEM, EDX, and Dielectric spectroscopy. The porous composite is comprised of varying weight percentages of (1, 3, and 5%) of GNS and 10 wt% PEPy-TP in PVDF. The thermal studies on the porous composites indicated that the decomposition occurred at a temperature around 270 and 470 °C corresponds to the PEPy-TP and PVDF/PEPy-TP/GNS (1, 3, and 5%), respectively. The EDX spectrum of neat PEPy-TP polymer and their porous composites of PVDF/PEPy-TP/GNS (1, 3, and 5%) result clearly shows the presence of all elements, such as C, O, S, and F with an atomic weight percentage also. The PVDF/PEPy-TP/5% GNS porous composites having a tremendous electrical conductivity and the dielectric constant value is 56 at 1 MHz and their conductivity of this polymer porous composites value is determined to be 4.9 × 10−6 S/cm at 100 kHz, respectively. [ABSTRACT FROM AUTHOR]

This experimental work aims to investigate the strain-rate effect on a unidirectional carbon fiber-reinforced epoxy laminate system with enhanced electrical conductivity under in-plane tension loading. The electrical modification, termed Functionalized Interlayer Technology (FIT), was realized through interleaving a ductile carrier surface-loaded with nano-sized electrically conductive silver nanowires (AgNWs). A benchmark analysis was carried out against a non-modified UD carbon/epoxy laminate with the intention of examining the influence of the modification on the mechanical properties of the material. High rate longitudinal tension properties, at around 180 s−1, were assessed using a split Hopkinson tension bar (SHTB) along with a high-speed camera. In-situ strain mapping using Digital Image Correlation (DIC) technique was employed to monitor the in-plane strain distribution and failure process of the composite laminates. The findings, for both laminate arrangements, demonstrated an absence of strain rate dependency on the tensile strength, modulus, and failure strain values. With respect to the electrical modification, FIT resulted in a decline of 18.8% on the longitudinal tensile modulus of the UD carbon/epoxy laminates. The findings covered in this article, along with those of the authors' previous publications [1-2], present for the first time the influence of strain rate on in-plane tension, compression as well as mode II interlaminar fracture toughness of electrically modified carbon/epoxy laminate system. [ABSTRACT FROM AUTHOR]

Four-dimensional (4D) printing technology is an innovative concept integrating conventional 3D printing additive manufacturing (AM) and smart materials programed to change properties or shape over time in response to environmental stimuli. This study aims to characterize the strength and electrical resistance of a commercial electrically conductive polylactic acid (PLA) with carbon black (CB) particles printed by fused filament fabrication (FFF) technique to evaluate the development feasibility of two sensor prototypes: (1) a load-cell sensor, and (2) a temperature sensor. Experiments were performed to study the orientation and raster angle--dependent mechanical and electrical performance of a PLA-CB conductive polymer manufactured by AM-FFF technology. A good agreement was observed between the data received from the manufacturer and the experimental density of the conductive AM-FFF PLA-CB three-point bending samples. The mechanical properties of 3D-printed PLA-CB were characterized based on three-point bending flexural test. Two build orientations (flat and upright) and three raster patterns (0°/90°, +45°/-45°, and concentric) were printed to check the optimal mechanical properties for electrical conductivity; six samples were printed for each one of the six configurations. The three-point bending flexural test results of the examined 36 specimens demonstrated that the samples printed in the concentric and +45°/-45° raster patterns exhibit the best mechanical properties, with the highest flexural strength and flexural modulus of elasticity in the flat orientation. Nevertheless, the concentric pattern has an advantage over the +45°/-45° pattern due to higher density and homogeneity. To examine the electrical resistance of the PLA-CB material another 12 specimens were printed and divided into four groups, each with different lengths. The electrical intrinsic resistivity was calculated from the geometry of the specimens and the measured resistance, with an average value of 13.2 [Ω·cm]. To check the production feasibility of a load-cell sensor prototype the effect of load on electrical conductivity was examined, however no effect of load on resistance was discovered. To prove the production feasibility of a sensor prototype for temperature measurements a preliminary device was designed and the effect of increasing and decreasing the temperature between 24 and 42°C on electrical resistance was examined. Based on the experimental results a calibration function was built linking between the temperature and the material's resistance. [ABSTRACT FROM AUTHOR]

Inducing electrical properties in thermoplastic materials and enhancing their mechanical properties with the addition of nanofiller in Fused Filament Fabrication (FFF) is the main purpose of the study. Multiwall carbon nanotubes (MWCNT) at different weight percentage (wt.%) loadings (0.1%, 0.5%, 1.0%, 2.5%, 5.0%, 10.0%) were incorporated into the Polyamide 12 (PA12) matrix. Melt mixing followed by filament extrusion was applied. Filaments were employed to 3D print specimens. A thorough study on the electrically Conductive Polymeric Composites (CPCs) electrical percolation threshold was carried out. Mechanical and thermomechanical response investigations were also conducted. Scanning Electron Microscopy (SEM) was employed to study the morphology of the 3D printed samples. The results showed a mechanical and thermomechanical properties enhancement for 5.0 wt.% filler's ratio. The electrical conductivity increased by increasing the filler loading. The 10% wt.% PA12/MWCNT nanocomposite additionally exhibited an electrothermal Joule-heating behavior. The antibacterial behavior was also tested with the agar well diffusion screening method, for gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus). A mild antimicrobial performance was observed. It can be concluded that the multi-functional PA12/MWCNT 3D printed lightweight CPCs developed herein could be applied in various applications, e.g. joule-heating devices, flexible conductors, and anti-static enclosures. [ABSTRACT FROM AUTHOR]

The development of multifunctional electromagnetic interference (EMI) shielding materials has garnered significant attention, yet achieving flexible composites that integrate EMI shielding, thermal conductivity, and other functionalities under low filler loading remains a challenge. This study presents a novel flexible composite with segregated structure prepared via a simple co-mixing and hot-pressing method. By selectively distributing conductive Liquid metal (LM) and Multi-wall carbon nanotube (CNT) on the surface of Polyurethane (TPU) particles, a continuous and compact conductive network is successfully constructed, enabling the attainment of a high EMI shielding effectiveness of 80.2 dB and a thermal conductivity of 4.8 W m−1 K−1 even at low LM loadings. Furthermore, the composite exhibits low-voltage-driven Joule heating performance, excellent photothermal conversion efficiency, and promising potential for wearable sensor applications. The combination of these outstanding properties highlights the great potential of LM-based composites for next-generation wearable devices. Multifunctional TLMC composites that integrate EMI shielding, thermal conduction, strain sensing, and photothermal conversion properties. [Display omitted] • TLMC flexible composite with segregated LM/CNT structure. • Remarkable photothermal and electrical-to-thermal conversion capabilities. • Excellent conductivity (100.2 S/cm) and superior EMI SE (up to 80.2 dB). • Strain sensing application capable of monitoring wearable motion. [ABSTRACT FROM AUTHOR]

Thermally and electrically conductive polymer composites (CPCs) have been widely used in smart and flexible electronics; however, huge challenges remain in simultaneously improving the electrical and thermal conductivity of CPCs while maintaining the satisfactory mechanical properties including sufficient strength and toughness. In this study, we propose an effective interfacial regulation approach to fabricate CPCs with a dual conductive network through decoration of Ag nanoparticles (AgNPs) onto the polyurethane (PU) nanofibers containing graphite nanoplatelets (GNPs), followed by hot-pressing. Rigid GNPs expand the PU nanofiber network, facilitating Ag precursor adsorption, while subsequent hot-pressing eliminates the big channels and pores inside nanofiber composite membranes and hence greatly enhance their mechanical properties. After hot-pressing, the synergistic dual conductive network with greatly reduced thermal and electrical contact resistance leads to significant improvements in both thermal and electrical conductivity (up to 27.71 W (m K)−1 and 1.87 × 106 S/m, respectively). Moreover, the mechanically robust CPCs with exceptional durability possess superior Joule heating performance at low voltages and heat dissipation capability. This study provides inspiration for designing highly thermally and electrically conductive CPCs with potential applications as flexible thermal interface materials. [Display omitted] [ABSTRACT FROM AUTHOR]

The thermoelectric properties, at temperatures from 30 °C to 100 °C, of melt-processed poly(ether ether ketone) (PEEK) composites prepared with 10 wt.% of carbon nanofibers (CNFs) are discussed in this work. At 30 °C, the PEEK/CNF composites show an electrical conductivity (σ) of ~27 S m−1 and a Seebeck coefficient (S) of −3.4 μV K−1, which means that their majority charge carriers are electrons. The origin of this negative Seebeck is deduced because of the impurities present in the as-received CNFs, which may cause sharply varying and localized states at approximately 0.086 eV above the Fermi energy level (EF) of CNFs. Moreover, the lower S, in absolute value, found in PEEK/CNF composites, when compared with the S of as-received CNFs (−5.3 μV K−1), is attributed to a slight electron withdrawing from the external layers of CNFs by the PEEK matrix. At temperatures from 30 °C to 100 °C, the σ (T) of PEEK/CNF composites, in contrast to the σ (T) of as-received CNFs, shows a negative temperature effect, understood through the 3D variable-range hopping (VRH) model, as a thermally activated hopping mechanism across a random network of potential wells. Moreover, their nonlinear S (T) follows the same behavior reported before for polypropylene composites melt-processed with similar CNFs at the same interval of temperatures. [ABSTRACT FROM AUTHOR]