Carbon Nanotube Yarns Research Articles

Fabrication and Characterization of Solid Composite Yarns from Carbon Nanotubes and Poly(dicyclopentadiene).

In this report, networks of carbon nanotubes (CNTs) are transformed into composite yarns by infusion, mechanical consolidation and polymerization of dicyclopentadiene (DCPD). The microstructures of the CNT yarn and its composite are characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and a focused ion beam used for cross-sectioning. Pristine yarns have tensile strength, modulus and elongation at failure of 0.8 GPa, 14 GPa and 14.0%, respectively. In the composite yarn, these values are significantly enhanced to 1.2 GPa, 68 GPa and 3.4%, respectively. Owing to the consolidation and alignment improvement, its electrical conductivity was increased from 1.0 × 105 S/m (raw yarn) to 5.0 × 105 S/m and 5.3 × 105 S/m for twisted yarn and composite yarn, respectively. The strengthening mechanism is attributed to the binding of the DCPD polymer, which acts as a capstan and increases frictional forces within the nanotube bundles, making it more difficult to pull them apart.

Self-Powered Carbon Nanotube Yarn for Acceleration Sensor Application

Accelerometers are indispensable for detecting accelerating forces in automotive electronic systems. Although several accelerometers have been developed, they are still unstable for vehicle dynamics' applications in the low-frequency range (0-20 Hz). Here, we report a novel type of accelerometer based on a coiled carbon nanotube (CNT) yarn as a self-powered and low-frequency range-covered acceleration sensor. The proposed sensor is designed in a compact fiber-like structure for practical applications. Open-circuit voltage (OCV) signals are consistently generated during the stretch-and-release process of the coiled CNT yarn by the applied sinusoidal accelerations, and the OCV changes increase linearly with increasing acceleration from 4.84 to 48.37 m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Our accelerometer exhibits excellent dynamic sensing performance in the low-frequency range compared with commercial accelerometers. In an application as a CNT yarn device configured with a mass load, the OCV change is linearly proportional to the applied acceleration. When our accelerometer is attached to a seatbelt in a vehicle, it generates OCV changes from the movement of the body mass underlying a certain acceleration change. Given its excellent sensing performance, the CNT yarn acceleration sensor could further be developed for practical applications, such as seatbelts and car seats with fabric and textile.

Sandwich-Structured Transition Metal Oxide/Graphene/Carbon Nanotube Composite Yarn Electrodes for Flexible Two-Ply Yarn Supercapacitors

Carbon nanotube (CNT) yarn has been regarded as a perfect electrode material for linear flexible supercapacitors. However, the supercapacitors composed of pure CNT yarn electrodes always have lower...

Systematic Investigations of Annealing and Functionalization of Carbon Nanotube Yarns.

Carbon nanotube yarns (CNY) are a novel carbonaceous material and have received a great deal of interest since the beginning of the 21st century. CNY are of particular interest due to their useful heat conducting, electrical conducting, and mechanical properties. The electrical conductivity of carbon nanotube yarns can also be influenced by functionalization and annealing. A systematical study of this post synthetic treatment will assist in understanding what factors influences the conductivity of these materials. In this investigation, it is shown that the electrical conductivity can be increased by a factor of 2 and 5.5 through functionalization with acids and high temperature annealing respectively. The scale of the enhancement is dependent on the reducing of intertube space in case of functionalization. For annealing, not only is the highly graphitic structure of the carbon nanotubes (CNT) important, but it is also shown to influence the residual amorphous carbon in the structure. The promising results of this study can help to utilize CNY as a replacement for common materials in the field of electrical wiring.

Carbon Nanotube Yarn Microelectrodes Promote High Temporal Measurements of Serotonin Using Fast Scan Cyclic Voltammetry.

Carbon fiber-microelectrodes (CFMEs) have been the standard for neurotransmitter detection for over forty years. However, in recent years, there have been many advances of utilizing alternative nanomaterials for neurotransmitter detection with fast scan cyclic voltammetry (FSCV). Recently, carbon nanotube (CNT) yarns have been developed as the working electrode materials for neurotransmitter sensing capabilities with fast scan cyclic voltammetry. Carbon nanotubes are ideal for neurotransmitter detection because they have higher aspect ratios enabling monoamine adsorption and lower limits of detection, faster electron transfer kinetics, and a resistance to surface fouling. Several methods to modify CFMEs with CNTs have resulted in increases in sensitivity, but have also increased noise and led to irreproducible results. In this study, we utilize commercially available CNT-yarns to make microelectrodes as enhanced neurotransmitter sensors for neurotransmitters such as serotonin. CNT-yarn microelectrodes have significantly higher sensitivities (peak oxidative currents of the cyclic voltammograms) than CFMEs and faster electron transfer kinetics as measured by peak separation (ΔEP) values. Moreover, both serotonin and dopamine are adsorption controlled to the surface of the electrode as measured by scan rate and concentration experiments. CNT yarn microelectrodes also resisted surface fouling of serotonin onto the surface of the electrode over thirty minutes and had a wave application frequency independent response to sensitivity at the surface of the electrode.

Analysis on the synthesis of vertically aligned carbon nanotubes: growth mechanism and techniques

This review article deals with orientation controlled growth of Carbon Nanotubes (CNTs). Vertically aligned CNTs (VACNTs) are considered as the best type of CNTs among all known forms. The present article covered various aspects required for the successful growth of orientation controlled CNTs especially vertically aligned form. We discussed in details about the important properties of VACNTs and the importance of VACNTs in materials science with relative applications. It included different types of CVD techniques which support the vertically aligned CNTs growth on the substrate and also supports its mass production with proper growth mechanism. We made a detailed discussion about catalyst engineering and different type of carbon sources. The catalyst lifetime is a key factor for growing long CNTs, so, the reason of catalyst poisoning and the protection of catalyst from poisoning is also a part of our article. We also explained in detail about the types of catalyst protector elements with their suitability on different temperature as well for different gases used for continuous growth of VACNTs, yarns of CNTs as well as bulk production of CNTs. We covered a broad study about the various catalysts, catalyst thickness and catalyst deposition techniques. The suitable supporting layers for different catalysts with their impacts on morphology as well as on the structure of as grown CNTs are also discussed. For reducing cost of VACNTs production, we included eco-friendly natural wastage materials for catalysts and as carbon precursor. It also included the process by which different designs and structures of VACNTs can be made specifically by bending of VACNTs during growth running time through the utilization of different catalyst reservoirs. The discussion made in present article on the growth of oriented CNTs will help to grow selective vertically aligned CNTs in the convenient way with economical rate and thereby helps in the mass production of CNTs.

A Review of Dry Spun Carbon Nanotube Yarns and Their Potential Applications in Energy and Mechanical Devices

A Review of Dry Spun Carbon Nanotube Yarns and Their Potential Applications in Energy and Mechanical Devices

Performance of EDT system for deorbit devices using new materials

A deorbit device is required for some microsatellites to meet space debris mitigation guidelines, although very challenging in terms of limited resources and reliability. Many groups are conducting research on post-mission disposal (PMD) devices using an electrodynamic tether (EDT) due to its high efficiency and simplicity. Since an EDT for microsatellites must be lightweight, with some strength, high conductivity, high survivability, and meet other requirements, such new materials as carbon nanotube yarn, metal-plated fiber, and metal-deposited thin film are assumed for a tape type tether. In order to determine the appropriate EDT dimensions such as tether width and length, the deorbit capabilities must be evaluated by numerical simulations in advance, as the thrust obtained varies depending on the EDT dimensions, orbital parameters, and other factors. The required resources of the EDT system such as mass and electric power can then be obtained for each orbit, satellite, and deorbit time. Thus, several prototypes of tape type tethers were made and evaluated in various tests.

Fabrication of CNT/Cu Composite Yarn via Single-Step Electrodeposition

Carbon nanotube (CNT)/Cu composite yarns were formed via a single-step electrodeposition process. A twisted CNT yarn composed of multiwalled CNTs (MWCNTs) was used. Copper was directly electrodeposited onto the CNT yarn under galvanostatic conditions using copper sulfate baths with and without additives. Four additives (polyethylene glycol (PEG), chloride anion (Cl−), bis(3-sulfopropyl)disulfide (SPS), and Janus green B (JGB)) that are well known as “via-filling additives” were used together. The surface and cross-sectional microstructures of the copper-deposited CNT yarns were analyzed. Copper was electrodeposited only onto the surface of the CNT yarn from the bath without additives, resulting in a copper-coated CNT yarn. By contrast, copper was deposited not only onto the surface but also into the interior of the CNT yarn from the bath with the additives. The amount of copper deposited into the CNT yarn tended to increase with increasing PEG and Cl− concentrations. The current density also affected the size and location of the deposited copper particles. When the electrodeposition conditions were optimized, copper was relatively homogeneously deposited into the interior of the CNT yarn, resulting in a CNT/Cu composite yarn.

Parameter Analysis of CNT Yarns in Smart 3-D Braiding Composites

Abstract An important method for making smart three-dimensional (3-D) braiding composites is to use embedded carbon nanotube (CNT) yarn sensors with 3-D braiding technology. According to the braiding structure of 3-D six-direction braiding composites, the mathematical model of carrier movement of braiding machine is constructed. The method for calculating the number and length of embedded CNT yarns with intelligent composites is proposed. The characteristics of resistance changing for CNT yarns under loading are analyzed. Experiments show that the error of the length and actual length of the CNT yarn calculated by the Bezier curve is less than 1 %. When the tensile strain exceeds 2 %, the strain of the embedded CNT yarns begins to appear nonlinear. The loading and unloading of the specimen have some influence on the resistance change of the CNT yarn. After the load is unloaded, the CNT yarn will produce the residual resistance.

Carbon nanotube yarn based thermoelectric textiles for harvesting thermal energy and powering electronics

We explore the fabric structural effect of thermoelectric textiles on power generation and achieve high power density for practical applications.

High-twist-pervaded electrochemical yarn muscles with ultralarge and fast contractile actuations

Carbon nanotube yarn muscles with a high-twist-pervaded and hierarchical structure show ultra-large and fast contractile actuations when driven by electrochemical ion injection.

Bioinspired microstructure-reorganized behavior of carbon nanotube yarn induced by cyclic stretching training

Microstructure-reorganized behavior is where the microstructure of a material can be reorganized under some conditions, such as temperature or moisture changes, electrical or mechanical stimulation.

Development of continuous CNT fibre-reinforced PMMA filaments for additive manufacturing: A case study by AFM-IR nanoscale imaging

High performance carbon nanotube fibres and yarns with similar strength to Kevlar could now offer significant structural reinforcement and multifunctionality to 3D printed parts. However, recently printed parts which were reinforced with highly-densified CNT yarns exhibited only modest mechanical properties due to poor wettability with polymers. In this work, PMMA is proposed for infiltration of CNT fibres produced via Floating Catalyst CVD, as the polymer may be printed at a lower temperature and is industrially used in resilient fibre-reinforced thermoplastic prepregs and laminates. Nanoscale chemical imaging by AFM combined infrared spectroscopy revealed good infiltration while the PMMA/CNT fibre composite filaments exhibited pronounced increase in tensile strength and Young’s modulus.

Production of CNT Yarns from Methane Gas for Use as Filaments in Incandescent Bulbs: Thermodynamic Properties of As-spun CNT Yarns

Energy efficiency is a minimal cost energy resource. It is critical in bridging the gap via reducing overall demand, allowing electricity supply to be expanded to meet increasing demand in a timely and sustainable way. Incandescent bulbs with tungsten filaments convert only about 10% of the input energy into light with the rest wasted as heat and resultant carbon dioxide gas emissions. This results in high energy and environmental inefficiency. Carbon nanotubes (CNT) yarns as filaments for replacement of tungsten in incandescent bulbs represent an economic option boosting high energy and environmental efficiency. In this study, CNT yarns were produced from methane, an abundant greenhouse gas currently flared in Africa. Synthesis of CNT yarns were carried out in a Floating Catalyst Chemical Vapour Deposition (FCCVD) reactor using ferrocene as the catalyst with direct spinning of CNT into yarn. The quality and morphology of the produced yarns at different temperatures (900 – 1000°C) were determined using Scanning Electron Microscope (SEM) and Raman Spectroscopy. The optimum temperature to produce CNT yarns was found to be at reactor temperature of 950°C. The thermodynamics associated with the production of the as-spun CNT yarns were determined by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Heat capacity of CNT yarns was calculated based on the measured heat flow at thermal stable state. A polynomial regression of the form: Cp=0.002T2 – 0.4512T+66.099 was proposed for the prediction of the thermodynamic values. Change in thermodynamic quantities of yarn such as entropy and enthalpy were determined based on the heat capacities calculated from fitted polynomial models using relationship of thermodynamic function.

The critical role of the forest morphology for dry drawability of few-walled carbon nanotubes

Carbon nanotube (CNT) yarns comprise few-walled CNTs (FWCNTs), mainly consisting of double- and triple-walled CNTs, and have several properties which are beneficial for practical bulk-scale carbon devices. These features include high tensile strength, electrical conductivity, thermal conductivity, chemical stability, and environmental tolerance. However, the synthesis window for fabricating CNT yarns with FWCNTs by the dry-spinning method is quite narrow and optimal conditions have yet to be determined. In this study, we fabricated CNT forests mainly comprised of FWCNTs at various synthesis conditions (temperature and time). The drawability of the CNT forests was characterized depending on the synthesis conditions. Our results show that optimum values exist for continuously drawable CNT forests in terms of both their height (>130 μm) and bulk density (>90 mg/cm3) for satisfying enough entanglement force between the CNT bundles. The diameter and number of walls of the CNTs are controlled by the temperature during the formation of catalyst particles because the sizes of catalyst particles are approximately equal to the outer diameter of CNTs. All temperature conditions in the range 350–500 °C, used to form catalyst particles, resulted in a drawable FWCNT forest. These insights will be useful for developing devices based on FWCNT yarns.

Measuring the radial elasticity of carbon nanotube yarns

Carbon nanotube yarn, one of the most important macroscopic architectures of carbon nanotubes, displays ultrahigh stiffness in axial direction yet remarkable softness in the radial deformation. However, in contrast to the axial mechanical behavior that has been extensively studied, the mechanical response to load applied in the radial direction, which is of fundamental importance to perform the material functions, was less explored. In this work, an experimental approach is developed to measure the radial elastic modulus of the carbon nanotube yarns with microscopic mechanisms elucidated by theoretical analysis. It is found that the measured radial elastic modulus increases with the increasing of the cycle loading number and the twist density of the carbon nanotube yarns, suggesting the tunability of the radial elasticity of carbon nanotube yarn by mechanical loading. Furthermore, a hierarchical model is proposed to explain the abovementioned structure-property relationship, revealing that the curvy, entangled, locally bundling nature strongly modulates the radial elastic modulus of the carbon nanotube yarns. This work not only provides essential insight in the radial deformability of carbon nanotube yarns, but also develops a method that could be applied to measure the radial mechanical properties of other micro-fibers.

Synergetic design of enlarged surface area and pseudo-capacitance for fiber-shaped supercapacitor yarn

In various wearable energy storage devices, the shape of fiber or yarn has many advantages owing to their compatibility with the environment in which they are deployed. We present a systematic approach to maximizing the capacitance of a supercapacitor yarn by significantly increasing the yarn's surface area by growing a high density of nanorods around the yarn, followed by coating the surface with a pseudo-capacitive material. The two-step strategy is implemented using a dry-spun carbon nanotube yarn-based electrode, which is surrounded by a zinc oxide nanorod forest that is coated by a pseudo-capacitive nickel-cobalt layered double hydroxide material. The flexible as-prepared electrode exhibits a maximum capacitance of 1065 mF cm−2 (1278 F g−1) at a scan rate of 5 mV s−1 and an excellent capacitance retention of 60.5% over 7000 cycles at a current density of 30 mA cm−2. The outstanding performance of the composite yarn supercapacitor can be ascribed to the enhanced ion accessibility to the deep surface of the nickel-cobalt layered double hydroxide layer through the porous carbon nanotube yarn. Furthermore, the symmetric supercapacitor configuration demonstrated nearly 100% capacity retention at a bending angle of 150°.

One-Minute Joule Annealing Enhances the Thermoelectric Properties of Carbon Nanotube Yarns via the Formation of Graphene at the Interface

Interfaces in nanocarbon materials are highly important, as they determine the properties of carbon-based devices. In terms of carrier and thermal transport properties, the interfacial features are...

Production of carbon nanotube yarns via floating catalyst chemical vapor deposition: Effect of synthesis temperature on electrical conductivity

Effect of synthesis temperature on the structure, morphology and crystallinity of as-synthesized CNT yarns via direct spinning was studied using Raman spectroscopy, x-ray powder diffraction (XRD) and thermogravimetric analysis (TGA). Effects of synthesis temperature on purity, morphology and thermal stability were related to the conductivity of the CNT yarns. It was observed that increase in synthesis temperature increased the sp2 content of the as-synthesized carbon nanotubes yarns as indicated by the decrease in ID/IG ratio and increase in oxidation temperature. Current-Voltage (I-V) relationship for the CNT yarns synthesized at 1000 °C indicates an increase in resistivity with increased applied voltage, indicating promising potential of the produced yarns as filaments for incandescent bulbs.