Conductive Polymer Composite Materials Research Articles

Features of the change in the thermal coefficient of electrical resistance upon heating electrically conductive composites of crystallizable polyolefins with carbon black

Objectives. To investigate electrically conductive polymer composite materials (EPCMs) based on crystallizable polyolefins and electrically conductive carbon black for the production of self-regulating heaters; to study the mechanism of the occurrence of positive and negative temperature coefficients (PTC and NTC) upon heating such composites.Methods. A comprehensive study of the structure and properties of crystallizable EPCMs with electrically conductive technical carbon was carried out. In order to measure the electrical characteristics of the composites, they were compacted into plates to model polymer heaters. Contact electrodes made of an ungreased brass mesh were embedded in their ends. The temperature dependencies of the electrical characteristics of the samples were investigated in a modified thermal chamber of an FWV 633.10 Vicat softening temperature meter. The change in the degree of crystallinity was analyzed by means of differential scanning calorimetry with a NETZSCH DSC 204 F1 Phoenix calorimeter. The dilatometric and rheological characteristics of the samples were studied using an IIRT-AM melt flow index tester.Results. It was determined that the self-regulation ability (an abnormally high positive thermal coefficient of electrical resistance) of selfregulating heaters made of composites of crystallizable polyolefins with electrically conductive technical carbon cannot be explained by the thermal expansion of EPCMs alone. It was shown that in crystallizable polyolefin-based EPCMs, the inversion of the thermal coefficients of electrical resistance (transition from PTC to NTC) is associated with a change in the aggregate state of EPCMs and the beginning of its transition to a viscous-flow state. A mechanism involving a sharp increase in the electrical resistance of self-regulating crystallizable polyolefin-based composite with electrically conductive technical carbon was proposed and substantiated. This mechanism takes into account the additional shear deformation effect produced on the crystalline phase of the EPCM by numerous expanding melt microvolumes formed at the early stages of the melting process with a minimum change in the degree of crystallinity.

Effect of Rheological on the Physical and Electrical Properties of Extruded Micro Carbon -LLDPE Composites

This study focuses on formulating and optimizing a conductive polymer composite (CPC) material tailored for electromechanical applications. Linear Low-Density Polyethylene (LLDPE) polymer and micro carbon particles derived from rice husk were compounded using a hot compaction process and melt blended through a single-screw extrusion machine. A mix of 50% loading of microcarbon particles was used in this research. It was determined that the experiment was successfully conducted, resulting in a stabilized density of approximately 1 g/cm³. The research demonstrates how the prototype Extruder Head effectively stabilizes the density of composites. Electrical conductivity demonstrated a notable increase in conductivity toward higher density. These findings underscore the successful development of a CPC material with improved electrical conductivity, making it a highly suitable tool for high carbon-loading composite material.

Preparation of high thermal conductivity vat photopolymerization used UV-curable resin synergistically enhanced by silicon nitride and boron nitride

Additive manufacturing (3D printing) technologies, especially vat photopolymerization (VPP), provide a cost-effective and efficient approach for the fabrication of heat dissipation devices with complex geometric designs. The incorporation of inorganic thermal conductive fillers into resin matrix is widely recognized as an effective way to enhance thermal conductivity. Notably, the synergistic effect of hybrid fillers can further enhance thermal conductivity. However, the consequent drastic increase in viscosity of the UV-curable resin may decrease the success rate and accuracy of printing on commercial VPP 3D printers. In this work, hexagonal boron nitride (h-BN) platelets and spherical h-BN together with β-Si3N4 are introduced into the UV-curable resin system. Corresponding results proved that h-BN together with β-Si3N4 provide a synergistic effect on the thermal conductivity enhancement compared to the filler in single morphology only. Moreover, owing to the spherical structure, low-viscosity UV-curable resin with high solid content can be prepared. In specific, a thermal conductive polymer composite material with a solid content of 60 wt% is prepared, which exhibits high thermal conductivity (1.42 W/mK), representing an enhancement of up to 610 % compared to neat resin. In subsequent application demonstrations, 3D printed heat dissipation devices with as-prepared resin composite material have been shown to effectively enhance the heat dissipation rate for the heating device.

Effect of microcarbon particle size and dispersion on the electrical conductivity of LLDPE-carbon composite

This experimental research aimed to develop a conductive polymer composite (CPC) material for electromechanical devices. The composite was made by incorporating conductive micro carbon derived from rice husks into a Linear Low-Density Polyethylene (LLDPE) polymer matrix using hot compaction. Variations of filler composition were used, with carbon loading of 50%, 45%, and 40%, and mesh sizes of #150, #200, and #250. The experimental results showed that particle size variations did not significantly affect composite density, but higher mesh selection improved filler dispersion within the matrix, resulting in higher electrical conductivity values. The optimal conductivity value of 9.43E-04 S/cm was achieved with a micro-carbon composition of 50% loading. However, decreasing micro carbon loading had a more significant impact on reducing electrical conductivity values.

Flexible Piezoresistive Polystyrene Composite Sensors Filled with Hollow 3D Graphitic Shells.

The objective of this research was to develop highly effective conductive polymer composite (CPC) materials for flexible piezoresistive sensors, utilizing hollow three-dimensional graphitic shells as a highly conductive particulate component. Polystyrene (PS), a cost-effective and robust polymer widely used in various applications such as household appliances, electronics, automotive parts, packaging, and thermal insulation materials, was chosen as the polymer matrix. The hollow spherical three-dimensional graphitic shells (GS) were synthesized through chemical vapor deposition (CVD) with magnesium oxide (MgO) nanoparticles serving as a support, which was removed post-synthesis and employed as the conductive filler. Commercial multi-walled carbon nanotubes (CNTs) were used as a reference one-dimensional graphene material. The main focus of this study was to investigate the impact of the GS on the piezoresistive response of carbon/polymer composite thin films. The distribution and arrangement of GS and CNTs in the polymer matrix were analyzed using techniques such as X-ray diffraction and scanning electron microscopy, while the electrical, thermal, and mechanical properties of the composites were also evaluated. The results revealed that the PS composite films filled with GS exhibited a more pronounced piezoresistive response as compared to the CNT-based composites, despite their lower mechanical and thermal performance.

Revealing the causes of degradation of an asymmetric ionic liquid supercapacitor with a composite polyaniline/carbon electrode

The extended window of electrochemical stability of ionic liquids and the high specific capacitance values of activated carbon (AC)/conductive polymer (polyaniline, Pani) composite materials are promising approaches to improve the performance of supercapacitors (SC).In this work, we studied the stability of an asymmetric AC//Pani-C cell with 1 M solution of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) in acetonitrile as an electrolyte. Pani-C (56 wt% of Pani) composite was prepared by oxidative polymerization of aniline in the presence of high surface area AC (SBET = 2300 m2‧g−1). Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission and scanning electron microscopies data confirmed the formation of Pani-C composite. Combination of cyclic voltammetry, galvanostatic charge/discharge method, and electrochemical impedance spectroscopy in 2- and 3-electrode cell configurations gave information about anodic (1 V vs. Ti) and cathodic (−1.8 V vs. Ti) potential limits of electrochemical stability, and potential of zero charge of Pani-C and AC.From these data, optimal mass ratio of Pani-C and AC electrodes was obtained for asymmetric SC assembly. It was found that after 500 charge/discharge cycles, the capacitance of the asymmetric AC//Pani-C SC decreased by 15% from 46.8 to 39.9 F·g−1 as a result of Pani-C degradation. The specific capacitance of AC remained virtually unchanged (decreased from 144 to 141 F·g−1), while that of Pani-C decreased by 8.7% from 230 to 210 F·g−1. Electrochemical measurements showed that degradation is accompanied by an increase in the working potential window of Pani-C (from 0.85 V to 0.97 V) and a shift in Emin…Emax working potentials from 0.15 … 1 to 0.52 … 1.49 V vs. Ti in the beginning and in the end of stability test, respectively. The last region is related to the potential for non-conductive pernigraniline formation (1.3 V vs. Ti). It was shown that the main reason of AC//Pani-C SC capacitance decay is a gradual increase in the operating potential window with a constantly shifts towards anodic values of positive Pani-C electrode, which resulted in accumulation of nonconductive polymer form that does not participate in charge accumulation.

PANI and PPy-Based Biosensing of Salt Stress in Plants: An Electrochemical Approach

Organic electrochemical transistor (OECT)-based biosensors fabricated from two different conducting polymer composite materials, carbon black/polyaniline and carbon black/polypyrrole have been demonstrated for direct, real-time, in-vivo monitoring of salt stress in plants. Similar in-vivo monitoring of salt stress in plants was also done by means of OECT-based biosensor fabricated from the conducting polymer Poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT: PSS) and a comparison has been drawn between the three types of biosensor. Electrochemical Impedance Spectroscopy studies were done for each biosensor in order to understand the dependence of its channel current on its control voltage and also to electrically model its channel. When a plant was subjected to salt stress, changes in ionic concentration in its sap were found to modulate channel current of the transistor-based device integrated in the plant. This current modulation was observed at the output of all the three devices, demonstrating the ability of all of them to monitor salt stress.

Thermoplastic Polyurethane/Carbon Nanotube Composites for Stretchable Flexible Pressure Sensors

Developing conductive polymer composites (CPCs) with high stretchability and high resistance response is a challenge in the field of flexible sensing. In this study, porous CPCs with a microdome array on the surface are prepared based on thermoplastic polyurethane (TPU) and carbon nanotubes (CNTs). TPU/CNT composites are designed to be strain sensors and pressure sensors capable of monitoring external strain and pressure stimuli. Due to the excellent electrical properties of carbon nanotubes, the synergistic effect of composite surface microstructure, and an internal porous structure, the sensor has greatly improved the detection range and sensitivity of traditional sensors. The sensing properties of CPC materials in terms of strain and pressure monitoring are perfectly balanced. The detection ranges of the strain sensor and pressure sensor are 0–160% and 0–55 kPa, respectively, and the highest sensitivity is gauge factor (GF) = 12.88 (90–160%) and sensitivity S = 0.08 (0–6.5 kPa), respectively. Based on the reversible change of the CNT conductive network under tensile/compression loading, the sensor has excellent stability and durability during cyclic loading. In addition, the TPU/CNT composite sensors can monitor human movements, bending of composite components, and pressure positions, showing great application prospects in electronic skin, wearable smart devices, and human–computer interaction.

Investigating the Electromechanical Properties of Carbon Black-Based Conductive Polymer Composites via Stochastic Modeling.

Conductive polymer composites (CPCs) have shown potential for structural health monitoring applications based on repeated findings of irreversible transducer electromechanical property change due to fatigue. In this research, a high-fidelity stochastic modeling framework is explored for predicting the electromechanical properties of spherical element-based CPC materials at bulk scales. CPC dogbone specimens are manufactured via casting and their electromechanical properties are characterized via uniaxial tensile testing. Model parameter tuning, demonstrated in previous works, is deployed for improved simulation fidelity. Modeled predictions are found in agreement with experimental results and compared to predictions from a popular analytical model in the literature.

CONDUCTIVE POLYMER COMPOSITE MATERIALS BASED ON FURAN POLYIMINES FOR BIPOLAR FUEL CELL PLATES

Conductive polymer composite materials for bipolar fuel cell plates with a polymer electrolyte membrane have been successfully prepared using 2,5-diformylfuran synthesized from plant biomass. The composites were prepared using a conductive filler (natural graphite) and polyimines from 2,5-diformylfuran and aromatic and aliphatic diamines (p-phenylenediamine, meta-toluenediamine, and hexamethylenediamine). The effect of polyimine content and its type on the electrically conductive and strength properties of materials has been studied. It is shown that the electrical conductivity of the composite increases with a decrease in the content of the polymer binder, while its mechanical properties change in the reverse order. The best materials were made using polyimine based on 2,5-diformylfuran and meta-toluenediamine (MTDA). The lowest value of interfacial contact resistance (0.01 Ohm·cm2) was shown by composites with 45% vol. binder content, and the highest mechanical strength (compressive and bending 21.8 and 32 MPa, respectively), containing 85% vol. polyimine. Sample MTDA-75 has demonstrated an optimal combination of electrical conductivity and mechanical properties. The interfacial contact resistance of the composite was 0.04 Ohm·cm2, and the strength was 15 and 22.5 MPa for compression and bending, respectively. Thus, composites based on polyimines from 2,5-diformylfuran and various diamines and natural graphite as an electrically conductive filler demonstrate great potential for the production of bipolar fuel cell plates with a polymer electrolyte membrane, and correspond to the strategic direction for the development of materials with minimal carbon footprint. For citation: Kataria Y.V., Klushin V.A., Kashparova V.P., Tokarev D.V., Smirnova N.V. Conductive polymer composite materials based on furan polyimines for bipolar fuel cell plates. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 3. P. 93-99. DOI: 10.6060/ivkkt.20236603.6766.

The monitoring of plant physiology and ecology: From materials to flexible devices

Plant health monitoring has gotten increasing concerns in recent years. Flexible devices offer a more effective mean of monitoring plants. In order to obtain plant information, the relevant physiological and ecological parameters that need to be concerned are summarized in this review. The aim is to provide a more comprehensive and explorable perspective. The research results and progress of flexible devices for plant monitoring in recent years are presented. This paper focuses on conductive materials for flexible device fabrication, including carbon-based materials (e.g. carbon nanotubes (CNTs), graphene), metallic materials (e.g. gold, silver), conductive polymer materials (e.g. polypyrrole, polythiophene), composite materials, biomass materials and hydrogel materials. In the end, we discuss the challenges and future potential of flexible devices for plant sensing at this stage. It is hoped that this will provide further inspiration for research and development of flexible sensing devices in the plant sector.

Влияние электропроводного технического углерода на свойства линейного полиэтилена низкой плотности

The effect of electrically conductive carbon black on the electrophysical and mechanical properties of the linear low-density polyethylene has been experimentally investigated. The structural parameters of carbon black have been determined, which have a significant effect on the electrical conductivity of carbon black and the electrical conductivity of polymer composite materials when it is used as a filler. It is established that the introduction of 10–20 wt. % carbon black in linear low-density polyethylene provides high conductivity of composite materials, while increasing their modulus of elasticity, but at the same time reduces elongation at break. It is shown that, in general, the studied carbon black is a promising filler in the development of electrically conductive polymer composite materials for electrical and radio engineering purposes.

Flexible and lightweight porous polyether sulfone/Cu composite film with bidirectional differential structure for electromagnetic interference shielding and heat conduction

Lightweight porous conductive polymer composite materials (CPCs) are up-and-coming electromagnetic interference (EMI) shielding materials. However, fair-sized thickness (>1 mm) and limited thermal conductivity hinder their application in modern integrated and miniaturized electronics. Herein, flexible bidirectional differential porous carbon fillers (C-fillers)/polyether sulfone (PES)/Cu (PCPES/Cu) composite films are fabricated via phase inversion technology followed by magnetron sputtering process. The bidirectional differential structure features with a top porous C-fillers/PES (PCPES) film and a bottom sputtering highly-conductive Cu thin layer. The PCPES film possesses hierarchical pore structure that is derived from mass transfer between solvent and nonsolvent. Owing to the bidirectional differential structure, an “absorption-reflection-reabsorption” shielding process is created to strengthen EMI shielding performance and relieve secondary microwave reflection in PCPES/Cu composite film. Its shielding effectiveness is as high as 59.7 dB, and specific SE/t is up to 6982.5 dB cm2 g−1. Notably, the reflection coefficient falls to 0.73, below other shielding materials with similar thickness. Further, the Cu thin layer can construct effective transmission channel of phonons in the plane direction, allowing thermal conductivity enhancement. The flexible lightweight EMI shielding composite films with satisfied thermal conductivity have extensive application prospects, such as aerospace, wearable electronics, and portable electronics.

Conductive Polymer Composites Made from Polypropylene and Recycled Graphite Scrap

Electric Discharge Machining (EDM) process uses electrodes made from graphite that wear out over time and are turned into scrap. In this research, EDM electrode scraps were recycled and turned into graphite powder (rGP). This rGP was used as a conductive filler to produce conductive polymer composite (CPC) material by combining it with polypropylene (PP) resin via melt compounding and compression moulding processes. The percolation threshold of this composite material changed when 30 wt% of rGP was added, whereby the insulative material changed became antistatic. The composite was able to achieve surface resistivity as low as 105 ohm/sq. However, the addition of higher rGP content deteriorated the tensile properties of composite, whereby the tensile strength of composite significantly decreased as compared to neat PP. The results also showed that the tensile modulus of this composite became higher, and the material became more brittle as compared to neat PP. However, the PP/rGP composite with 50 wt% filler content reduced the tensile modulus due to plasticising effect caused by the agglomeration of rGP. The addition of high filler content on PP/rGP composite also caused an increase in processing torque. This was due to the restriction of rGP particles to the melt flow of molten PP. The morphological analysis found that the PP/rGP composites with higher amounts of filler content were highly agglomerated and formed conductivity paths within the PP matrix. The increase of rGP content highly improved the thermal stability of composite. The findings of this study show that the rGP has the potential to be used as a conductive filler for producing conductive composite material.

Fluoroplastic- and Bio-Based Composites Materials for PEM Fuel Cells Bipolar Plates

Conductive polymer composite materials for polymer electrolyte membrane fuel cells bipolar plates have been successfully prepared from renewable plant biomass sources and copolymers of tetrafluoroethylene with vinylidenefluoride. The composites are based on various conductive fillers (natural, oxidized and colloidal graphite’s) and polymer binder (the 5-HMF synthesis by-product or fluoroplastic). The influences of type and content of binder and type of conductive filler on the mechanical properties and conductivity were investigated. Conductivity of the composites decreases with increasing of polymer content, but its mechanical properties changes inversely. Composite based on 5-HMF by-products (content 30 wt.%) and colloidal graphite as a filler meets the DOE requirements for a mechanical strength. Flexural and compressive strengths were 25 and 32 MPa, respectively. Composites based on fluoroplastic 32 (content 30 wt.%) and fluoroplastic 42 (content 20 wt.%) with colloidal graphite as a filler and fluoroplastic 42 (content 20 wt.%) with nature graphite have flexural strength values close to the target value of DOE and amounted to 24, 17 and 19 MPa, respectively. Interfacial contact resistance depends to a greater extent on the nature of the filler and is maximum for composites based on natural graphite. Composites based on fluoroplastic 42 at any filler content correspond to the requirements DOE ≤ 0.01 ohm∙cm2. Composite based on 5-HMF synthesis by-product (resin) and fluoroplastic with conductive filler (colloidal graphite) shows a great potential application as bipolar plates for PEMFCs.

Effect of Multi-Sized Graphite Filler on the Mechanical Properties and Electrical Conductivity

This research successfully fabricated conductive polymer composites (CPCs) prepared using multiple sizes of graphite filler (40, 100, 150, and 200 µm) that provided excellent network formation within the fillers and polypropylene matrix which further improved both electrical conductivity and flexural strength. An important discussion on the fabrication technique, including compression moulding and injection moulding was conducted, to manufacture CPC materials with a thickness less than 3 mm. The findings of this study suggested that fabricating CPCs using the compression moulding technique with a graphite composition of 75 wt. % exhibited better network connectivity as the electrical conductivity increased to 15 Scm-1. Also, compared to the three sizes of graphite filler (40/100/200 µm) it resulted in 13 Scm-1, with two sizes (40/200 µm) reporting better electrical conductivity at 15 Scm-1. This demonstrated that the addition of multiple sizes was not necessarily due to agglomeration occurring. The resultant graphite composites of 40/200 µm possessed a more stable structure having a thin composite layer (2.5 mm) which promoted better electrical conductivity suitable for bipolar plate used in proton exchange membrane fuel cells.

Enhancement of Electromagnetic Interference Shielding Performance and Wear Resistance of the UHMWPE/PP Blend by Constructing a Segregated Hybrid Conductive Carbon Black-Polymer Network.

The low-percolation-threshold conductive networking structure is indispensable for the high performance and functionalization of conductive polymer composites (CPCs). In this work, conductive carbon black (CCB)-reinforced ultrahigh-molecular-weight polyethylene (UHMWPE)/polypropylene (PP) blend with tunable electrical conductivity and good mechanical properties was prepared using a high-speed mechanical mixing method and a compression-molded process. An interconnecting segregated hybrid CCB–polymer network is formed in electrically conductive UHMWPE/PP/CCB (UPC) composites. The UPC composites possess a dense conductive pathway at a low percolation threshold of 0.48 phr. The composite with 3 phr CCB gives an electrical conductivity value of 1.67 × 10–3 S/cm, 12 orders of magnitude higher than that of the polymeric matrix, suggesting that CCB improves both the electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) of the composite at the loading fraction over its percolation threshold. The composite with 15 phr CCB presents an absorption-dominated electromagnetic interference shielding effectiveness (EMI SE) as high as 27.29 dB at the X-band. The composite also presents higher tribological properties, mechanical properties, and thermal stability compared to the UP blend. This effort provides a simple and effective way for the mass fabrication of CPC materials with excellent performance.

Flexible conductive polymer composite materials based on strutted graphene foam

Electrically conductive polymer composites (CPCs) with bendable and stretchable deformation capacity are one of key challenges for flexible cable, wearable electronics and so on. 3D graphene network is an emerging graphene bulk material beyond the pre-exiting graphene powders and films, which is also an advanced 3D-network filler instead of traditional powdery fillers, for the construction of CPCs. Herein, a strutted-graphene foam is produced at large scale, whose shape is customizably designed. The strutted graphene is further applied as the filler for making a composite. The fabricated composite shows comprehensively enhanced mechanical modulus, thermal conductivity, and electrical conductivity, which increase by 40%, 54%, and 8 orders of magnitude at a low filling fraction of 0.15 vol% of strutted graphene, respectively. The fabrication process is facile, low-cost, and scalable, which can be envisaged as a rational design and engineering of advanced polymeric composites.

A comparative study between vapor phase polymerized PPy and PEDOT - Thermoplastic polyurethane composites for ammonia sensing

In this study, in situ vapor phase polymerization (VPP) of (1) 3,4-ethylenedioxythiophene (EDOT) and (2) pyrrole (Py) on an oxidant-impregnated thermoplastic polyurethane (TPU) substrate was conducted to produce a (1) PEDOT-TPU hybrid film and (2) PPy-TPU hybrid film. Scanning electron microscopy, atomic force microscopy, and energy dispersive x-ray spectroscopy confirmed the formation of uniform, rough surfaces of PPy and PEDOT on the TPU matrix. Both PPy-TPU and PEDOT-TPU films showed excellent thermal stability across the temperature range of 300 °C–400 °C and enhanced mechanical properties, depicted by very high stress and strain values. The performance of these hybrid films to detect ammonia (NH3) gas was investigated and then optimized under the effects of varying temperature, ammonia concentration, and monomer type used. The PEDOT-TPU and PPy-TPU showed remarkable sensitivity to NH3 gas, with coefficients of variation of 0.9858 and 0.9653, respectively. Particularly, the PEDOT-TPU sensor showed higher responsiveness to NH3 at higher operating temperatures owing to its higher surface roughness and thermal stability. These flexible, stretchable, smart conducting polymer composite materials fabricated using VPP are therefore potential candidates for monitoring toxic and non-toxic gases.

High-fidelity stochastic modeling of carbon black-based conductive polymer composites for strain and fatigue sensing

The research presented in this paper aims to improve on the accuracy and computational efficiency of previously reported stochastic models for predicting the electromechanical properties of conductive polymer composite (CPC) materials with nanoparticle constituents. The proposed approach provides a means of quantifying the degree of particle dispersion in a mixture—a parameter that is most often reported as qualitative- and process-specific. CPC-based sensors have recently garnered attention in the field of structural health monitoring due to their atomic similarities with composite materials that are an increasingly popular commodity among numerous industries. In this study, CPCs composed of carbon black nanoparticles and phenolic-based resin epoxy are manufactured and characterized both experimentally and via computational methods. A high-fidelity stochastic modeling solution is proposed to estimate electromechanical properties of such CPCs. Qualitative analysis on the fidelity of the stochastic model is demonstrated. The potential uses for the model and validation techniques are discussed.