Fabrication Of Conductive Composites Research Articles

Wearable Liquid Metal Composite with Skin-Adhesive Chitosan-Alginate-Chitosan Hydrogel for Stable Electromyogram Signal Monitoring.

In wearable bioelectronics, various studies have focused on enhancing prosthetic control accuracy by improving the quality of physiological signals. The fabrication of conductive composites through the addition of metal fillers is one way to achieve stretchability, conductivity, and biocompatibility. However, it is difficult to measure stable biological signals using these soft electronics during physical activities because of the slipping issues of the devices, which results in the inaccurate placement of the device at the target part of the body. To address these limitations, it is necessary to reduce the stiffness of the conductive materials and enhance the adhesion between the device and the skin. In this study, we measured the electromyography (EMG) signals by applying a three-layered hydrogel structure composed of chitosan-alginate-chitosan (CAC) to a stretchable electrode fabricated using a composite of styrene-ethylene-butylene-styrene and eutectic gallium-indium. We observed stable adhesion of the CAC hydrogel to the skin, which aided in keeping the electrode attached to the skin during the subject movement. Finally, we fabricated a multichannel array of CAC-coated composite electrodes (CACCE) to demonstrate the accurate classification of the EMG signals based on hand movements and channel placement, which was followed by the movement of the robot arm.

Improved Salt Spray Resistance of Silver-Plated SiO2 via Self-Assembled Mercapto Inhibitors

Highly conductive fillers are an essential raw material in the fabrication of conductive composites, paste, ink, adhesive, etc. Still, susceptibility to salt spray erosion remains a serious issue for silver-based fillers. Herein, we first prepared highly conductive silver-plated microspherical silica (Ag/pSiO2) through catechol/polyamine surface functionalization and subsequently formed a self-assembled inhibition layer on the surface of Ag/pSiO2 by using (3-mercaptopropyl)trimethoxysilane (KH590) to enhance the salt spray erosion resistance. The results suggested that the self-assembled KH590 greatly improved the salt spray erosion resistance of the Ag/pSiO2. The total shielding effectiveness (SEt) of the composites protected by KH590 was 106 dB after the salt spray erosion, which was even 16 dB higher than that before erosion. In contrast, the SEt of the composites without KH590 decreased significantly from 111 to 76 dB. Further studies revealed that the KH590 inhibitor strongly prevented the penetration of Cl– and subsequently enhanced the salt spray resistance. Considering the facile and effective preparation, this strategy could be applied in large-scale silver-based EMI shielding materials.

Polylactic acid-graphene emulsion ink based conductive cotton fabrics

Manufacturing bio-based and biodegradable materials for electronic applications is a swiftly growing field today. This approach can effectively tackle the future electronic waste problems. However, the preparation of such sustainable materials with high conductivity remains a challenging task. Moreover, in many cases, the use of noxious solvents may be unavoidable. This study shows the feasibility of an aqueous emulsion-based printable conductive ink to be used in the field of flexible electronic devices. The emulsion ink contains polylactic acid (PLA) as a binder and graphene nanoplatelets as a conductive filler. It shows an encouraging electrical conductivity of 34.5 S/m when spray-coated onto a cotton fabric. Moreover, the conductive composite fabrics were very stable in cyclic strain tests, suitable for wearable electronics. A hot pressing post-treatment of the printed composite fabrics improved the electrical conductivity by up to two times. Additionally, the coatings also enhanced the mechanical properties of the cotton fabrics by increasing the Young's modulus values almost twice compared to pristine fabric. This eco-friendly composite ink can be used as strain sensors for transforming certain electronic components into biodegradable versions.

Dependence of Electrical Conductivity on Phase Morphology for Graphene Selectively Located at the Interface of Polypropylene/Polyethylene Composites.

Conductive composites of polypropylene (PP) and polyethylene (PE) filled with thermally reduced graphene oxide (TRG) were prepared using two different processing sequences. One was a one-step processing method in which the TRG was simultaneously melt blended with PE and PP, called TRG/PP/PE. The second was a two-step processing method in which the TRG and the PP were mixed first, and then the (TRG/PP) masterbatch was blended with PE, called (TRG/PP)/PE. The phase morphology and localization of the TRG in TRG/PP/PE and (TRG/PP)/PE composites with different PP/PE compositions were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The TRG was found to be selectively dispersed in the PE phase of the TRG/PP/PE composites, resulting in a low percolation threshold near 2.0 wt%. In the (TRG/PP)/PE composites, the TRG was selectively located at the PP/PE blend interface, resulting in a percolation threshold that was lower than 1.0 wt%. With the addition of 2.0 wt% TRG, the (TRG/PP)/PE composites exhibited a wide range of electrical conductivities at PP/PE weight ratios of 10 w/90 w to 80 w/20 w. Moreover, electrical and rheological measurements of the composites revealed that the co-continuous phase structure is the most efficient candidate for the fabrication of conductive composites.

A Systematic Study on Morphological, Electrical and Electromagnetic Shielding Performance of Polypyrrole Coated Polyester Fabrics

Functional conducting polymeric composites with micro and nano structures have received great attention due to technological applications in electrical, optical, and magnetic materials and devices. Electrically conductive polymeric textile surfaces are used for smart/functional textile applications such as electromagnetic shielding, anti static coatings, wearable electronic sensors, heat generating textiles etc. In this study, micro/nano scale conductive polymer coatings were obtained on polyester fabrics by in-situ chemical polymerization of pyrrole. Electromagnetic shielding performance of polyester-polyprrole (PES-PPy) conductive composite fabrics were investigated by coaxial holding method of ASTM D 4935. Spectroscopic (FTIR-ATR, XPS), morphologic (SEM), thermal (TGA) and electrical (Four Point Probe) characterizations were performed.

Structure design of multi-functional flexible electrocardiogram electrodes based on PEDOT:PSS-coated fabrics

Herein, Polyester woven fabrics as the matrices for the experimental group, while cotton knitted fabrics, cotton woven fabrics, and Polyethylene terephthalate (PET) mesh cloth used as the matrices for the control groups, at 40 °e, using 3,4-ethoxylene dioxy thiophene (EDOT)as the polymer monomer, FeCl3as the oxidant, and poly(sodium-p-styrenesulfonate) (PSS) as the dopant, are separately coated with PEDOT:PSS polymer to prepare flexible conductive composite fabrics. The influences of the fabric pattern, oxidant concentration, and monomer concentration on the electrical performance of composite fabrics are optimized. The maximal electrical conductivity of PET-based composite fabrics (218 S/m) occurs when monomer concentration is 0.035 mol/L, the molar ratio of oxidant to monomer is 2.5, and the dopant concentration is 2.5 g/L. Moreover, bacteriostasis rate of this composite fabric reaches 71.8%. Furthermore, by electrocardiogram (ECG) simulated human body unit test as well as human body ECG test, the optimal PET-based composite fabric electrode both has a lower impedance which helps form the stabilized ECG signal. The resulting fabric electrodes retain the soft and breathable advantages from fabrics and reduce the discomfort for a long-term use of conventional electrographic gel, thereby validating the empirical evidence for mobile, portable, wearable ECG electrodes.

Synthetic Multiscale Graphene Aerogel Polymer Composites with High‐Conductive Performances for Hyperthermia Equipment

3D interconnection structures are preconstructed by the hydrothermal method, which is considered an effective way to prepare conductive polymers. However, the fabrication of conductive composites to meet the application remains a challenge for relatively low conductive filler content. Herein, a 3D interconnection network is designed by combination of 2D functionalized graphene oxide (FGO), 1D acidified carbon nanotube (ACNT), and 0D copper element to establish conductive aerogel, which is used as reinforcement to prepare conductive FGO‐ACNT/epoxy nanocomposites. Both elementary Cu and crisscrossed ACNT act as bridges among graphene nanosheets, which is beneficial to electron or phonon conduction, making the nanocomposites possess high‐efficiency electric heating performance and temperature stability. Its electrical conductivity reaches 3.33 S m−1 with only 1.1% of FGO‐ACNT, and the temperature quickly reaches up to 344 °C at the voltage of 9 V within 73 s. Importantly, the FGO‐ACNT/epoxy nanocomposite shows prompt heat‐responsivity, and it can heat up to 60 °C within 7 s from room temperature. When the FGO‐ACNT/epoxy nanocomposite is used as a hyperthermia equipment, it exhibits excellent electrical conductivity, prompt heat‐responsivity, and good temperature stability. These excellent properties make it possible to be used as a physical therapy device to help human health.

Preparation Technique and EMI Shielding Evaluation of Flexible Conductive Composite Fabrics Made by Single and Double Wrapped Yarns

Electronics products and communication equipment release electromagnetic (EM) waves in service. EM waves affect biological health and precision instrument accuracy. This study purposes to fabricate flexible conductive composite fabric which is made of complex yarn using metal (stainless steel, copper) fibers and PET filaments. Complex yarn is formed by a rotor twisting machine, at varying values of wrapped number (6.5-16 turns/cm) and lamination number (single-layer, double-layer). Results show that when the complex yarn was wrapped 16 turns/cm, volume resistivity reached 2.9 Ohm-cm and conductivity reaches 0.408 S/cm. Four layers of conductive composite plied with 0°/90°/ 0°/ 90° resulted in the optimum electromagnetic shielding effectiveness, up to 47.7 dB.

Dependence of sheet resistance of nickel-plated PANi/PTT composite fabric on electroless plating conditions

Flexible and stretchable conductive composite fabrics have wide applications, including wearable sensors, antenna, electrodes, solar batteries, signal, or power transmission. For most of applications, the electrical conductive fabrics need a low sheet resistance and antioxidation. To improve the stability and the electrical conductivity of PANi/PTT composite conductive fabric, some conductive composite fabrics were prepared by electroless nickel plating on PANi/PTT composite fabrics in the aqueous nickel sulfate solutions. The sheet electrical properties of the composite fabric were evaluated by the van der Pauw method, and the effect of the chemical plating conditions such as reducing agent, complexing agent, and buffer agent concentrations were investigated on the sheet resistance as well as the mechanical properties of fabric substance. The results show that the lower sheet resistance of composite fabrics was observed at the concentrations of NiSO4, 25 g/L, NaH2PO2, 20 g/L, Na3C6H5O7, 15 g/L, CH3COONa, 20 g/L, respectively. Additionally, the mechanical properties of the Ni/PANi/PTT composite fabrics were improved in comparison with those of PANi/PTT composite fabrics.

In situ iodoalkane-reduction of graphene oxide in a polymer matrix: an easy and effective approach for the fabrication of conductive composites

Graphene/polyimide composites with the conductivity of 2.22 S m−1 were fabricated via in situ reduction of graphene oxide by 1,2-diiodoethane.

Structure design and property evaluation of silver/stainless steel composite fabric

This study presents a fabrication method for functional commingled yarns and prepared conductive knitted fabrics for shielding electromagnetic waves and electrostatic discharge. Stainless steel filament was used as core yarn, polyethylene terephthalate filament or silver yarn was used as wrapped yarn producing polyethylene terephthalate/polyethylene terephthalate/stainless steel filament or silver/silver/stainless steel filament commingled yarns via filaments hollow spindle spinning system and then knitting into silver/stainless steel composite fabric. The effects of cycle number and metal content on air permeability, surface resistance, and electromagnetic shielding properties of resultant knitted fabrics were discussed. Besides, influences of number of layers and lamination angle on electromagnetic shielding were also investigated intensively. The result shows that, conductive composite fabrics made by silver/silver/stainless steel filament commingled yarns and 450D polyethylene terephthalate plied filaments had higher surface resistance of 3.4 Log(Ω/sq) and 5.6 Log(Ω/sq), respectively, in coursewise and walewise directions. Electromagnetic shielding varied with number of layer, lamination angle, cycle number, and metal content. When six layers of conductive knitted fabrics were laminated with 45°, electromagnetic shielding reached 15 dB at 1–3 GHz frequency. The highest air permeability, 317.6 cm3/cm2/s, occurred at single-layer conductive composite fabric.

High conductive ethylene vinyl acetate composites filled with reduced graphene oxide and polyaniline

A conductive network composed of reduced graphene oxide (RGO) planes and polyaniline (PANI) chains was designed and fabricated by in situ polymerization of aniline monomer on the RGO planes. It was further used for fabrication of conductive composites with a polymer matrix–ethylene vinyl acetate (EVA). The composites achieve improved conductivity at a low filler loading although the host polymer–EVA–is of insulator. For instance, compared to the pure EVA polymer, the conductivity of the composite filled with 4.0wt.% RGO and 8.0wt.% PANI increases from 1.2×10−14Scm−1 to 1.07×10−1Scm−1. In addition, thermal stability of the composites is also enhanced by the filler loading.

Preparation of polyaniline/nylon conducting fabric by layer‐by‐layer assembly method

AbstractIn this article, layer‐by‐layer assembly technology was used to prepare polyaniline (PANI)/nylon conducting fabrics. PANI/nylon conductive composite fabrics were prepared by deposition of polyanion (PSS) and polycation (aniline cation) alternately. The pretreatment with PSS was discussed. The influence of the reaction time, aniline concentration, acid concentration and assembly time on the conductivity, and K/S values of composite fabric was studied. The optical reaction condition of assembly should be: the concentration of PSS was 20 g/L, the PSS‐treated nylon immersion in blended bath for 24 min, ammonium persulfate 0.1 mol/L, aniline 0.1 mol/L, p‐toluene sulfonic acid 0.3 mol/L. In the end, the conductive composite fabrics were characterized by fourier transformed Infrared‐attenuated total reflection spectroscopy and compared with pure nylon fabrics. At the same time, scanning electron microscopy, atomic force microscope (AFM), thermogravimetric analysis (TG), and mechanical properties were studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

In situ polymerization of aniline on acrylamide grafted cotton

AbstractIn this article, polyaniline (PANI)/cotton composite were prepared by in situ polymerization on the grafted cotton. First, acrylamide was grafted onto cotton cellulose using a radical graft polymerization process and some influencing factors were studied. Then polyaniline/cotton conductive composite fabrics were prepared by chemical in situ polymerization on the grafted cotton. The influences of the concentration of ammonium persulfate, aniline, hydrochloric acid, and the reaction time to the conductivity and K/S of composite fabric were studied. By contrasting, graft brought on an improvement of about one order of magnitude to the conductivity of composite fabric. The strength, TG, FTIR‐ATR, and SEM of prepared fabric were measured. The thermal stability and tear strength of composite fabric reduced, whereas PANI exhibited a rough but uniform, coherent PANI coating on surface of cotton fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The conductive polyaniline/poly(ethylene terephthalate) composite fabrics

Conductive composite fabrics were prepared by chemical polymerization of aniline on poly(ethylene terephthalate) (PET) fabrics in the aqueous hydrochloride acid solutions using potassium dichromate as the oxidant. The effect of the polymerization conditions such as temperature, oxidant, aniline and hydrochloride acid concentrations was investigated on the electrical surface resistance and polyaniline (PAn) content of PAn/PET composite fabrics. The maximum PAn content and the lower electrical resistance of composite fabrics were observed at the HCl concentrations of 0.25 M and 1.5 M, respectively. The electrical surface resistance of the PAn/PET composite fabrics was decreased under vacuum five-fold more than the ones kept under in air. The properties of PAn/PET composite fabrics such as density, diameter and moisture regain were also investigated in comparison with the those of pure PET. The conductive composite fabrics were characterized by surface resistance, FTIR and TGA techniques.