Static Charge Dissipation Research Articles

Surface-Localized Chemically Modified Reduced Graphene Oxide Nanocomposites as Flexible Conductive Surfaces for Space Applications.

Thermoplastic polymers are a compelling class of materials for emerging space exploration applications due to their wide range of mechanical properties and compatibility with a variety of processing methods, including additive manufacturing. However, despite these benefits, the use of thermoplastic polymers in a set of critical space applications is limited by their low electrical conductivity, which makes them susceptible to static charging and limits their ability to be used as active and passive components in electronic devices, including materials for static charge dissipation, resistive heaters, and electrodynamic dust shielding devices. Herein, we explore the microstructural evolution of electrically conductive, surface-localized nanocomposites (SLNCs) of chemically modified reduced graphene oxide and a set of thermoplastic polymers as a function of critical thermal properties of the substrate (melting temperature for semi-crystalline materials or glass transition temperature for amorphous materials). Selected offsets from critical substrate temperatures were used to produce SLNCs with conductivities between 0.6-3 S/cm and surface structures, which ranged from particle-rich, porous surfaces to polymer-rich, non-porous surfaces. We then demonstrate the physical durability of these electrically conductive SLNCs to expected stress conditions for flexible conductive materials in lunar applications including tension, flexion, and abrasion with lunar simulant. Small changes in resistance (R/R0 < 2) were measured under uniaxial tension up to 20% strain in high density polyethylene and up to 500 abrasion cycles in polysulfone, demonstrating the applicability of these materials as active and passive flexible conductors in exterior lunar applications. The tough, electrically conductive SLNCs developed here could greatly expand the use of polymeric materials in space applications, including lunar exploration, micro- and nano-satellites, and other orbital structures.

A controllable fabrication of flat absorber dual-layer coating with electric shielding on 6061 aluminum alloy by PEO with nanoparticles additive

In spacecraft, thermal control coatings with anti-static functionality are vital for electronic packages to ensure proper operation of devices and instruments while preventing the reduction of component lifetime due to extreme temperatures or electrostatic discharge. However, simultaneously integrating thermal control and static charge dissipation into one coating remains a huge challenge. Herein, a dual-layer black coating composed of an Al2O3-In2O3-P2O5-SiO2 glass bottom layer embedded with crystalline indium tin oxide (ITO) and a top layer with ITO and carbon nanotubes (CNTs) as sealed conductive and radiative components grows in situ on the 6061 aluminum alloy surface using a modified PEO method with nanoparticles additive under special parameters, experiencing one-step liquid-plasma-assisted particle deposition and sintering (LPDS) process. During the LPDS process, the addition of CNTs to the electrolyte promotes the deposition and sintering of ITO nanoparticles on the bottom layer, resulting in the transition from a single-layer coating to a dual-layer coating. CNTs with high absorption/emissivity assisted further by the infrared-trapping effect of the micro/nanostructure lead to flat absorber dual-layer coating. The black coating offers both high solar absorptance (~0.93) in the 0.2–2.5 μm waveband and infrared emissivity (~0.94) in the 3–20 μm waveband. Notably, CNTs with high aspect ratio connect the ITO nanoparticles to form a complete conductive channel on the coating surface, thus eliminating in-plane charges. At only 1.27 × 102 Ω, the surface resistivity of the dual-layer coating is five orders of magnitude lower than that of the single-layer Al2O3 coating (1.15 × 107 Ω). Such an all-in-one design provides a feasible and sustainable strategy for anti-static black products in space applications.

Pursuit of electroconducting thermoplastic vulcanizates: activated charcoal-filled polypropylene/ethylene–propylene–diene monomer blends with upgraded electrical, mechanical and thermal properties

Conducting polymer blends are getting attention due to their demanding applications in static charge dissipation processes. In the current study, polypropylene (PP)– and ethylene–propylene–diene monomer-based nanocomposites, filled with varying loadings of intrinsically conducting activated charcoal (AC) nanoparticles, were blended in the presence of methyl methacrylate (MMA)-based compatibilizer and sulfur-based vulcanization system to prepare electroconducting thermoplastic vulcanizates (TPVs). Fourier-transform infrared spectroscopy, confirming successful grafting of MMA on PP chains, was employed to perform structural analysis of the samples. Relative distribution of filler in polymer and rubber phases, level of homogeneity of filler distribution and optimum state of filler dispersion were analyzed via scanning electron microscopy. Improved degree of crystallinity, thermal stability and other characteristic temperatures of the prepared specimens were determined via differential scanning calorimetry and thermogravimetric analysis. Increasing filler contents considerably improved tensile strength, stiffness, and hardness of the prepared TPVs. Doping of AC into electrically insulator TPVs turned them into almost a semiconducting material as indicated by significant enhancement in their electrical conductivity values.

Durable electroless Ni and Ni-P-B plating on aromatic polysulfonamide (PSA) fibers with different performances via chlorine-aided silver activation strategy

Abstract Electroless Ni and Ni-P-B plating were conducted respectively on aromatic polysulfonamide (PSA) fibers following a new chlorine-aided silver activation system in the present work. Firstly, PSA fibers were treated in NaClO-HCl solution to impart chlorine to the surface area followed by immersion in AgNO 3 solution to convert the chlorine to AgCl particles. After subsequent reduction of AgCl to metallic Ag seeds in NaBH 4 solution, electroless Ni and Ni-P-B plating were performed respectively. These two kinds of adherent and continuous coatings activated and anchored by the silver seeds, which were both resistant against sonication, were deposited onto PSA fibers with different electrical, magnetic, electromagnetic shielding, and corrosion resistance properties. Both plated PSA fibers can act directly as electromagnetic interference shielding and static charge dissipation materials, or act as excellent base layers for other subsequent metallic coatings according to different requirements, and then show great potential applications in coaxial cables and wear protection for aerospace, aviation, microelectronics, military industry and telecommunications.

Preparation of Silver-Deposited Aromatic Polysulfonamide Fibers with Excellent Performance via Electroless Nanoplating Using a Chlorine-Aided Silver Activation System

Silverized aromatic polysulfonamide (PSA) fibers were prepared through a novel chlorine-aided silver activation system followed by electroless nanoplating in the present work. The Ag/AgCl interfacial layer was first introduced to the fiber surface via successive immersion in NaClO-HCl solution, AgNO3 solution, and NaBH4 solution, whose activating and anchoring abilities were then employed to coat an adhesive and uniform silver layer onto PSA fibers by electroless nanoplating. The obtained silverized PSA fibers possessed high electroconductivity, minor paramagnetism, excellent electromagnetic shielding effectiveness, outstanding tensile property, and thermostability, which were also resistant against sonication and exhibited good electroconductivity after exposure in air for half a year. They can act as electromagnetic interference shielding and static charge dissipation materials in coaxial cables and wear protection, which then show a wide application prospect in aerospace, telecommunications, and milita...

Effect of graphene oxide on the structural and electrochemical behavior of polypyrrole deposited on cotton fabric

Improving the electrical response of polypyrrole–cotton composite is the key issue in making flexible electrode with favorable mechanical strength and large capacitance. Flexible graphene oxide/cotton (GO/Cotton) composite has been prepared by dipping pristine cotton in GO ink. The composite‘s surface was further modified with polypyrrole (Ppy) via chemical polymerization to obtain Ppy/GO/Cotton composite. The composite was characterized using SEM, FTIR and XRD measurements, while the influence of GO in modifying the physicochemical properties of the composite was also examined using TG and cyclic voltammetry. The achieved mean particle size for Ppy/Cotton, Ppy/GO/Cotton and GO estimated using Scherrer formula are 58, 67 and 554nm, respectively. FTIR spectra revealed prominent fundamental absorption bands in the range of 1400–1800cm−1. The increased electrical conductivity as much as 2.2×10−1Scm−1 for Ppy/GO/Cotton composite measured by complex impedance, is attributed to the formation of continuous conducting network. The partial reduction of GO on the surface of cotton (GO/Cotton) during chemical polymerization can also affect the conductivity. This simple, economic and environmental-friendly preparation method may contribute towards the controlled growth of quality and stable Ppy/GO/Cotton composites for potential applications in microwave attenuation, energy storage system, static electric charge dissipation and electrotherapy.

Waterborne Epoxy Nanocoatings Modified by Nanoemulsions and Nanoparticles

Electrically conductive coatings are required for static charge dissipation in power ground network. In the present investigation electrically conductive nanocoatings were prepared by the incorporation of graphite, nano-SiO2 concentrate, acrylic nanoemulsion and fluorocarbon emulsion onto the waterborne epoxy polymer. The nanosize distribution of nano-SiO2 concentrate and nanoemulsion was characterized with laser diffraction analyzer and scanning electron microscopy (SEM). From the results of SEM image, the graphite particles were well distributed in conductive coating. The corrosion resistance and thermal stability of nanocoatings were comparatively studied by SEM and thermogravimetry (TG). The corrosion-inhibiting properties of the conductive nanocoatings were investigated by salt immersion test. The measurements of contact angle, bonding strength and heat-freeze charge demonstrated that 1.5–2.0 wt% nanoparticles improve the resistance to pollution, adherence and resistance to heat-freeze charge of conductive nanocoatings. The measured results of surface electric resistance of nanocoatings demonstrated that a small amount of nano-SiO2 particles could enhance the conductivity in the corrosive environment.

Electrical properties of conductive fabrics for operating capacitive touch screen displays

Electrically conductive textiles have many potential applications, such as sensors, static charge dissipation, and electro-magnetic interference shields. In this study, two different types of core spun yarns were produced with silver-plated nylon filaments as the conductive material. The electrical characteristics of the core spun yarns and the fabric samples knitted with these yarns were investigated. It was clear that the surface resistance of each type of knitted fabric depends on the surface exposure of the conductive materials. However, both knit types exhibited reasonable features for application as a touching operator for capacitive touch screen panels.

Highly dispersed and electrically conductive polycarbonate/oxidized carbon nanofiber composites for electrostatic dissipation applications

The influence of low cost, commercially oxidized carbon nanofibers (ox-CNFs) on the morphological, thermal, mechanical and electrical properties of polycarbonate (PC) composites was examined. Using a simple solution mixing process leads to good dispersion and high packing density of CNFs in the resultant composites. The composite materials exhibit a dramatic improvement in the DC conductivity; for example, increasing from 2.36 × 10 −14 S/m for PC to ca. 10 −2 S/m for the composite at only 3.0 wt.% of CNFs, and exhibits a very fast static charge dissipation rate. Dynamic mechanical analysis showed a remarkable increase in storage modulus (282%) at 165 °C, compared to pure PC. Thermogravimetric analysis showed that thermal stability of the composites increased by 54 °C compared to the pure PC. To our knowledge, the measured electrical conductivity and thermal properties for PC/CNF are the highest values yet reported for PC/CNF composites at comparable loadings. The AC/DC conductivity is shown to play an important role to predict the state of dispersion.

Application of Static Charge Dissipation to Mitigate Electric Discharge Bearing Currents

Today, the physical cause-and-effect chains of inverter-induced high-frequency bearing currents have been well understood, but little has been known on not only theoretically possible, but also cost-effective mitigation techniques for a certain drive configuration. This paper focuses on the mitigation of discharge bearing currents, which occur predominantly with smaller motors of up to several kilowatts. We present a new mitigation technique where any voltage build-up across the bearing is discharged via static charge dissipation through a parallel path before an electric breakdown inside the bearing occurs. The technique is based on the field emission effect, has ultralow friction and negligible wear, and is very robust toward contamination, when compared with conventional carbon-based brushes.

Ultrathin Transparent Conductive Films of Polymer-Modified Multiwalled Carbon Nanotubes

Deposition of multiwalled carbon nanotubes modified by poly(2-vinylpyridine) (CNT-g-P2VP) from aqueous dispersions at low pH is an effective method to prepare homogeneous ultrathin films with a tunable CNTs density. A percolation threshold of 0.25 mug/cm2 and a critical exponent alpha = 1.24 have been found from dc conductivity measurements. The sheet resistance value agrees with the percolation theory for 2D films. According to AFM and electrical measurements, even when only 5% of the surface is covered by CNT-g-P2VPs, the sheet resistance is of the order of 1 MOmega/sq, which indicates that conductivity is imparted by a network of an ultralow density. When the film transmittance decreases down to approximately 70% at 550 nm, the occupied surface area is approximately 15% and sheet resistance falls down to approximately 90 kOmega/sq. These data show that undesired in-plane clustering does not occur upon the dispersion casting of the films and that high-quality networks of CNT-g-P2VPs are built up. The electrosteric stabilization of the CNT-g-P2VP dispersions in water at low pH is at the origin of this desired behavior. Although the multiwalled CNT films prepared in this work are less conductive and less transparent than the SWNTs films, they could find applications, e.g., in touch screens, reflective displays, EMI shielding, and static charge dissipation.

Studies on graphite based conductive paint coatings

Electrically conductive coatings are mainly required for static charge dissipation and electromagnetic/radio frequency interference (EMI/RFI) shielding. Electrically conductive coatings are prepared by the incorporation of the metallic pigments/graphite onto the binder. In the present investigation graphite is used as the conductive filler and epoxy polymer as binder. Optimization of the solid content and pigment volume concentration (PVC) of the coating is done by varying the composition of the binder and pigment volume. To get the minimum resistivity value offered by the coating. The resistivity of the coating was measured by means of the four-probe resistivity method. The effect of inclusion of carbon black as additional pigment is also studied. The results are presented and discussed in this paper.

Electrically conductive cement-based materials

Electrically conductive cement-based materials are useful for electrical grounding, lightning protection, resistance heating, static charge dissipation, electromagnetic interference (EMI) shielding, cathodic protection, and thermoelectric energy generation. The science and applications of electrically conductive cement-based materials are reviewed. In addition, a comparative study of the effectiveness of various electrically conductive admixtures (discontinuous forms of steel and carbon) for lowering the electrical resistivity of cement shows that the effectiveness decreases in the order: steel fibre of diameter 8 μm, steel fibre of diameter 60 μm, carbon fibre of diameter 15 μm, carbon nanofibre of diameter 0·1 μm, coke powder (< 75 μm) and graphite powder (< 1 μm). For EMI shielding, the effectiveness decreases in the order: steel fibre of diameter 8 μm, coke powder (< 75 μm), carbon nanofibre of diameter 0·1 μm, graphite powder (< 1 μm), steel fibre of diameter 60 μm, carbon fibre of diameter 15 μm, and steel dust of size 0·55 mm. By using steel fibre (8 μm diameter) at 0·72 vol.%, a resistivity of 16 Ω cm and an EMI shielding effectiveness of 59 dB (1 GHz) were attained. The carbon admixtures cause the absolute thermoelectric power to be more positive, whereas the steel admixtures can cause the absolute thermoelectric power to be more positive or more negative. In particular, steel fibre of diameter 60 μm at 0·2 vol.% causes the absolute thermoelectric power to be strongly negative (−63 μV/°C). Moisture loss has no effect on the absolute thermoelectric power, but increases the resistivity.

Electrically conductive cement-based materials

Electrically conductive cement-based materials are useful for electrical grounding, lightning protection, resistance heating, static charge dissipation, electromagnetic interference (EMI) shielding, cathodic protection, and thermoelectric energy generation. The science and applications of electrically conductive cement-based materials are reviewed. In addition, a comparative study of the effectiveness of various electrically conductive admixtures (discontinuous forms of steel and carbon) for lowering the electrical resistivity of cement shows that the effectiveness decreases in the order: steel fibre of diameter 8 μm, steel fibre of diameter 60 μm, carbon fibre of diameter 15 μm, carbon nanofibre of diameter 0·1 μm, coke powder (&lt; 75 μm) and graphite powder (&lt; 1 μm). For EMI shielding, the effectiveness decreases in the order: steel fibre of diameter 8 μm, coke powder (&lt; 75 μm), carbon nanofibre of diameter 0·1 μm, graphite powder (&lt; 1 μm), steel fibre of diameter 60 μm, carbon fibre of diameter 15 μm, and steel dust of size 0·55 mm. By using steel fibre (8 μm diameter) at 0·72 vol.%, a resistivity of 16 Ω cm and an EMI shielding effectiveness of 59 dB (1 GHz) were attained. The carbon admixtures cause the absolute thermoelectric power to be more positive, whereas the steel admixtures can cause the absolute thermoelectric power to be more positive or more negative. In particular, steel fibre of diameter 60 μm at 0·2 vol.% causes the absolute thermoelectric power to be strongly negative (−63 μV/°C). Moisture loss has no effect on the absolute thermoelectric power, but increases the resistivity.

Nanocomposite Films derived from Alkoxysilane Terminated Amide Acid Oligomers and Carbon Nanotubes

AbstractLow color, space environmentally stable, polymeric materials with sufficient electrical conductivity for static charge dissipation are of interest for potential applications on Gossamer spacecraft. One method of imparting electrical conductivity while maintaining optical clarity is through the use of single wall carbon nanotubes (SWNTs). Both theory and research on SWNTs have shown them to be conductive. However, SWNTs are very difficult to uniformly disperse in a polymer. The approach described herein was to use oligomers endcapped with functional groups that could condense with functionalities present on purified, laser ablated SWNTs. Low color, radiation resistant amide acid oligomers endcapped with trialkoxysilane groups were combined with SWNTs. Since the SWNTs were purified by an oxidative process (nitric/sulfuric acid treatment), they have functionalities such as hydroxyl and carboxylic acid groups that can condense with the terminal alkoxysilane groups. After mixing at room temperature, the mixtures were used to cast films that were subsequently stage-cured up to 300°C for 1 hour in air. During this thermal treatment, imidization and condensation occurred. The chemistry, physical, and mechanical properties of the resulting nancomposite films will be presented.

Static Dissipation Mechanism in Carpets Containing Conductive Fibers

The mechanism of static charge dissipation in carpets containing electrically conductive fibers is investigated. Incorporating conductive fibers in a carpet, even as isolated conductors, results in greatly reduced static charge accumulation on people as they walk across the carpet. Results of this work show that static charge dissipation depends on free ion formation around the tips of conductive fibers by corona discharge. We propose that the amount of charge accumulated by a person walking on a carpet is an equilibrium between the rate of charge formation and rate of charge neutralization through recombination with free ions of opposite sign produced by corona discharge around conductive fibers. We describe a method of measuring the corona current emanating from carpet tufts containing conductive fibers as a function of voltage. The amount of charge built up on a person walking on a carpet is inversely related to the corona current.

Poly(3,4-ethylenedioxythiophene) and Its Derivatives: Past, Present, and Future

An overview of one of the most successful conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDT) and its derivatives, is presented, detailing its early development, the synthesis of numerous hybrid and derivative materials, along with a description of the broad array of properties accessible and a description of a set of the more prominent applications in which they can be utilized. Synthetic flexibility and facility is the key to the many new 3,4-ethylenedioxythiophene- (EDT-) based monomers, oligomers, and (co) polymers. These (co) polymers provide highly conducting and especially stable doped states, a range of optical properties with electronic bandgaps varying across the entire visible spectrum, and enhanced redox properties, making them useful for numerous electrochemical devices. Present and future applications for PEDT that are discussed include static charge dissipation films and electrode materials in solid electrolyte capacitors.

Poly(3,4-ethylenedioxythiophene) and Its Derivatives: Past, Present, and Future

An overview of one of the most successful conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDT) and its derivatives, is presented, detailing its early development, the synthesis of numerous hybrid and derivative materials, along with a description of the broad array of properties accessible and a description of a set of the more prominent applications in which they can be utilized. Synthetic flexibility and facility is the key to the many new 3,4-ethylenedioxythiophene- (EDT-) based monomers, oligomers, and (co) polymers. These (co) polymers provide highly conducting and especially stable doped states, a range of optical properties with electronic bandgaps varying across the entire visible spectrum, and enhanced redox properties, making them useful for numerous electrochemical devices. Present and future applications for PEDT that are discussed include static charge dissipation films and electrode materials in solid electrolyte capacitors.

A study of the electrostatic behavior of carpets containing conductive yarns

This paper describes experiments to characterize the role of triboelectric charging in developing static charge as people walk on carpets and further experiments to quantify the role of corona ionization to minimize static charge accumulation. The Modified Inclined Plane test, a test currently gaining acceptance in the electronics industry, was used to measure triboelectric charging effects. Results indicate that this test was not a good predictor of static charge accumulation as measured by the body voltage on a person after a standard walk test. A test was developed to measure the effectiveness of corona discharge ionization caused by conductive filaments in carpet for limiting static charge accumulation. Results of this test have shown that, for carpets with good static charge dissipation properties, charge reduction via corona occurs on a time scale of about 0.1 s and that conductive latex greatly enhances the corona effect. Another test was developed to investigate the corona discharge properties of the conductive yarns themselves, without being incorporated into the carpet. Results of this test have shown that the corona voltage to initiate corona discharge depends largely on conductive fiber geometry and, that the conductivity vs. applied across the series combination of conductive yarn and air gap deviates significantly from Ohm's law behavior.

Conducting Polymers: Emerging Commercial Materials .

Conducting polymers are materials of recent origin. They are obtained by polymerisation of simple organic monomers and doping with electron acceptor or donor species and show conductivity ranging from that of a semiconductor to that of metal. These materials are now available with unique electronic and optical properties of metals and semiconductors in combination with the attractive mechanical and processable advantages of polymers. The field has progressed to a level of maturity consistent with a new set of opportunities to develop Wide range of applications based upon conducting polymers as materials for industrial products.Examples include: static charge dissipation, EMI shielding, flexible light emitting diodes, transparent electrodes, batteries, gas sensors, gas separators, etc. Many of the conducting polymers and devices based on them are now available commercially.