Aligned Nanotubes Research Articles

Mechanism of Co3O4-TiO2 Nanocomposite Formation with Enhanced Photocatalytic Performance

TiO2 nanotubes are tubular structures that have garnered significant attention in materials science and engineering due to their unique properties and diverse applications. In this study, highly ordered and well aligned TiO2 nanotubes were successfully synthesized through anodization of Ti foil in ethylene glycol (C2H6O2) containing ammonium fluoride (NH4F) and hydrogen peroxide (H2O2) at 60 V for 30 minutes. The effectiveness of TiO2 as a photocatalyst under solar light is limited by its wide band gap and high recombination rate of charge carriers. To address these limitations, TiO2 nanotubes were modified with cobalt oxide. The resulting Co3O4-TiO2 nanocomposite was synthesized using a wet impregnation technique, aiming to enhance the photocatalytic performance of TiO2 nanotubes across a broader range of the solar spectrum. The formation of Co3O4-TiO2 nanocomposite is by immersing the TiO2 nanotubes in the metal salt precursor solution of Co(NO3)2 for a certain soaking period. The soaking cycle was repeated a few times to ensure the deposition of cobalt oxide nanostructures on the TiO2 nanotube samples. This diffusion interstitial process via wet impregnation was time dependent, which altered the amount of cobalt loaded on the nanotube's surface. The addition of cobalt significantly improved the photodegradation activity of the nanotubes under visible light, outperforming bare TiO2 nanotubes. This enhancement is likely due to the cobalt acting as shallow traps, which effectively promote the separation of photogenerated charge carriers.

Aligned Semiconducting Carbon Nanotubes for Commercial Logic and RF Electronics

Carbon nanotubes are exceptional semiconductors that offer larger current densities and faster switching than conventional Si and GaAs devices, making nanotubes promising for meeting the performance and energy efficiency needs of next-generation electronics. However, the successful commercialization of carbon nanotubes necessitates the control over semiconducting purity, alignment, packing density, and scalability. The simultaneous control of these characteristics has been a major challenge preventing the integration of nanotubes in industrial electronics and the full exploitation of their electronic properties. This talk will present an overview of recent technological developments and methods that progress towards these goals.In these methods, semiconducting (purity of >99.99%) carbon nanotubes are deposited on target substrates via scalable alignment methods at room temperatures. These individual methods separately enable the deposition of quasi-aligned (±28°) nanotube arrays (~50 nanotubes µm-1) demonstrated across 100 mm substrates, highly-aligned (±6°) nanotube arrays (~100 nanotubes µm-1) demonstrated across 100 mm substrates, and the selective-area deposition of highly-aligned nanotube (±7°) arrays (~up to 250 nanotubes µm-1). The nanotube arrays with high packing density (~250 nanotubes μm-1) yield exceptional current densities of 2 mA μm-1 and transconductances of 1 mS μm-1 at VD of -0.6V. Importantly, due to the low-temperature nature of the deposition processes, these techniques offer a direct path towards the alignment of carbon nanotubes directly on Si and other materials, such as GaN or plastics, to enable high-performance 3D integrated circuits.

Evaluation of multi-walled carbon nanotubes alignment during 3D printing of poly(acrylonitrile-butadiene-styrene) nanocomposite filaments

Nanocomposites incorporated with one-dimensional electrical conductive materials such as carbon nanotubes have been used in many applications in various industries. In this research, the filaments made of poly (acrylonitrile-butadiene-styrene) (ABS) containing 1, 3, and 5 wt% multi-walled carbon nanotubes (MWCNT) were first prepared and then printed in three directions and two printing speeds. The rheological and electrical percolation thresholds were found to take place at 0.32 and 0.96 wt% MWCNT, respectively. Using the Casson plot, it was revealed that the yield stress of the nanocomposites containing 5 wt% MWCNT was 70 times higher than that of the pristine ABS. The results also indicated that the electrical resistance decreased from 17.4 to 6.8 Ω with the increase in printing speed from 4 to 20 mm/s, respectively. The alignment of the nanofillers was examined using X-ray diffraction method. It was found from the azimuth angle that the materials printed at higher printing speed had more orientation, with respect to the director, in comparison with that of printed at lower speed.

Carbon nanotube fibers with dynamic strength up to 14 GPa.

High dynamic strength is of fundamental importance for fibrous materials that are used in high-strain rate environments. Carbon nanotube fibers are one of the most promising candidates. Using a strategy to optimize hierarchical structures, we fabricated carbon nanotube fibers with a dynamic strength of 14 gigapascals (GPa) and excellent energy absorption. The dynamic performance of the fibers is attributed to the simultaneous breakage of individual nanotubes and delocalization of impact energy that occurs during the high-strain rate loading process; these behaviors are due to improvements in interfacial interactions, nanotube alignment, and densification therein. This work presents an effective strategy to utilize the strength of individual carbon nanotubes at the macroscale and provides fresh mechanism insights.

Different crystalline phases of aligned TiO2 nanotubes and their UV photoelectric properties

Different crystalline phases of aligned TiO2 nanotubes and their UV photoelectric properties

Simple synthesis of acyl coupling conjugated microporous polymers monolithic material for synergistic capture of PM and CO2 in flue gas and process simulation

Adsorption and separation technologies based on physical adsorbents have the advantages of simple operation, low heat of adsorption and easy regeneration. They have received much attention for the capture of CO2 and PM from flue gases. However, the inherent “trade-off” between adsorption capacity and adsorption selectivity, as well as the high gas permeation resistance after powder processing and shaping, severely limit the prospects for industrial applications. Here, acyl functional groups were strategically introduced into polymer frameworks to successfully synthesize monolithic adsorbents (AC-CMPs) with a hierarchical pore structure for PM capture and CO2/N2 selective adsorption. The three-dimensional network structure composed of aligned hollow nanotubes effectively enhances the dispersion and mass transfer of gas flow per unit volume. Based on the porous media, multiphase flow model and discrete phase model, the gas flow process of PM trapped by AC-CMPs was simulated using Fluent. The simulation dynamically revealed the relationship between permeability resistance and filtration efficiency. The highly delocalized π-π conjugated porous skeleton linked by continuous covalent bonds endowed AC-CMPs with good stability, which prevented them from degrading in humid and high-temperature environments, thus keeping the adsorption capacity unchanged. The high polarity environment generated by the open oxygen atoms within the AC-CMPs framework, along with a high micro/mesopore ratio, enable it to achieve a CO2 adsorption capacity of 2.07 mmol/g at 273 K and 1 bar. Ideal adsorption solution theory calculations (IAST) and CO2/N2 column breakthrough experiments confirmed the excellent CO2 selectivity of AC-CMPs under realistic carbon capture conditions.

Removal of conjugated polymer on carbon nanotube array by dry process

With the progress in the purity and alignment of semiconductor carbon nanotubes (CNTs), how to efficiently remove the conjugated polymers twining round CNTs has become an important and urgent matter for the further development of CNT electronics. The removal of conjugated polymers (CPs) by wet cleaning will inevitably lead to the destruction of the morphology of aligned CNT array films, which will cause the monolayered CNTs to form agglomeration or stacking. Therefore, it is necessary to develop a dry method to remove CPs on the aligned CNT films. In this work, we studied the thermal decomposition characteristics of CNTs and CPs in detail, and found that the ratio of the oxidative decomposition rate of CNTs and CPs could reach up to 35.7 in the oxygen environment at 450 °C. The transmission electron microscopes (TEMs) show that such a dry treatment process can effectively remove the polymer on CNTs without affecting the morphology of CNT arrays. The Raman spectrum show that ratio of G/D of the annealed sample is as high as 41.8, which indicates that the CNTs are not detectable damaged during the annealed process. The fabricated field-effect transistors (FETs) with a length of 2 μm exhibit a current on/off ratio higher than 104 and a current density higher than 660 μA/μm, which further justifies that the CNT arrays treated by the dry method exhibit high quality.

Ultrathin Langmuir-Blodgett film of functionalized single-walled carbon nanotubes for enhanced acetone sensing

Acetone is one of the important volatile organic compounds which needs to be detected from the industrial effluent and as a bio-marker from breath of diabetic patients. Here, ultrathin Langmuir-Blodgett (LB) film of octadecylamine- functionalized single-walled carbon nanotubes (ODA-CNT) was formed on interdigitated gold electrodes and was employed for acetone vapor sensing using the impedance spectroscopy (IS) at room temperature. The LB film deposited in liquid-like phase of the Langmuir monolayer of ODA-CNT revealed aligned nanotubes. Being a reducing agent, acetone interacts readily with the CNTs through the transfer of electrons. Using IS, multiparameter were measured with respect to both frequency and acetone vapor concentration. Principal component analysis (PCA) of the IS data revealed capacitance as the most suitable parameter for acetone vapor sensing using the ODA-CNT film. A very low limit of detection (0.5 ppm) and a wide detectable concentration range (1–300 ppm) for acetone sensing using the LB film of ODA-CNT was obtained. The 2D calibration map revealed that the sensing performance of acetone using LB film was much better as compared to that of drop-cast film of ODA-CNT and LB film of pristine CNTs. The superior sensing performance of the LB film of ODA-CNT is attributed to the uniform and aligned nature of the nanotubes, leading to a coherent behavior due to interaction with the acetone molecules. This study shows the potential of LB films of ODA-CNT for sensitive and low level detection of acetone vapor at room temperature.

Polyetherimide (PEI) nanocomposite with WS2 nanotubes.

Nanocomposite materials, integrating nanoscale additives into a polymer matrix, hold immense promise for their exceptional property amalgamation. This study delves into the fabrication and characterization of polyetherimide (PEI) nanocomposite strings fortified with multiwall WS2 nanotubes. The manufacturing process capitalizes on the preferential alignment of WS2 nanotubes along the string axis, corroborated by scanning electron microscopy (SEM). Mechanical measurements unveil a remarkable acceleration of strain hardening in the nanocomposite strings, chiefly attributed to the WS2 nanotubes. Structural analyses via X-ray diffraction (XRD) and wide-angle X-ray scattering (WAXS) reveal intriguing structural alterations during tensile deformation. Notably a semi-crystalline framework ∼100 nm in diameter surrounding the WS2 nanotubes emerges, which is stabilized by the π-π interactions between the PEI chains. The amorphous majority phase (97% by volume) undergoes also major structural changes upon strain becoming more compact and closing-up of the distance beweeetn the PEI chains. Dynamic mechanical analysis (DMA) demonstrates improved thermal stability of the evolved semi-crystalline π-π oriented PEI molecules, characterized by delayed thermal "structural melting", underscoring the pivotal role of the WS2 nanotubes in reinforcing the nanocomposite. The insight gained in this study of WS2 nanotube-reinforced PEI nanocomposite strings, could offer diverse applications for such tailor-made polymeric materials.

Indoor Photovoltaic Fiber with an Efficiency of 25.53% under 1500 Lux Illumination.

Photovoltaic devices represent an efficient electricity generation mode. Integrating them into textiles offers exciting opportunities for smart electronic textiles-with the ultimate goal of supplying power for wearable technology-which is poised to change how electronic devices are designed. Many human activities occur indoors, so realizing indoor photovoltaic fibers (IPVFs) that can be woven into textiles to power wearables is critical, although currently unavailable. Here, a dye-sensitized IPVF is constructed by incorporating titanium dioxide nanoparticles into aligned nanotubes to produce close contact and stable interfaces among active layers on a curved fiber substrate, thus presenting efficient charge transport and low charge recombination in the photoanode. With the combination of highly conductive core-sheath Ti/carbon nanotube fiber as a counter electrode, the IPVF shows a certified power conversion efficiency of 25.53% under 1500lux illuminance. Its performance variation is below 5% after bending, twisting, or pressing for 1000 cycles. These IPVFs arefurther integrated with fiber batteries as self-charging power textiles, which aredemonstrated to effectively supply electricity for wearables, solving the power supply problem in this important direction.

(Invited) Aligning Dense Arrays of Semiconducting Carbon Nanotubes for Logic and RF Technologies

Semiconductors are materials with electrical conductivity that can be switched on and off, that have allowed for nearly all electronics. However, most semiconductor devices utilize silicon, a microelectronics technology more half a century old. Silicon is now being extended to its limit and cannot meet the needs of next-generation devices.Carbon nanotubes are nanoscale semiconducting wires that conduct more electricity per area than silicon and more rapidly switch between on and off states with less voltage, making them ideal for next-generation fast, low-energy logic and high-speed, linear RF devices. However, no one has yet been able create a process for employing nanotubes commercially. In raw form, nanotubes are disordered and tangled and thus do not conduct electricity well. For nanotubes to be most useful, they must be lined up in the same direction in a single layer so that electricity can rapidly and efficiently travel through them. This has been a long-standing roadblock.This talk will present recent discoveries at the University of Wisconsin on (1) purifying and aligning semiconducting nanotubes into massively parallel arrays and (2) the research and development of semiconducting carbon nanotubes for logic and radio frequency technologies. We have pioneered nanotube array fabrication technologies that enable the (a) partial alignment of nanotubes (±30˚) via shear (demonstrated 100 mm wafer-scale); (b) finer alignment (±6˚) at liquid-liquid interfaces (demonstrated 100 mm size-scale); and, (c) the selected-area deposition of nanotube arrays (±7˚) in lithographically-defined patterns combining topographical and chemical features (demonstrated 25 mm size-scale). Most recently, we have discovered a powerful new mechanism for driving the self-assembly of nanotubes into aligned arrays, by coaxing them to form two-dimensional liquid-crystals. We have uncovered that when nanotubes are segregated to liquid-liquid interfaces, mesogenic interactions cause them to self-align (within +/-5.7 degrees so far) and self-assemble into dense arrays (> 100 per micron) like those needed for microelectronics. The assembled nanotubes are easily integrated on silicon substrates at room-temperature and integrated into high-performance devices.APL (2014); ACS Nano (2014); Science Advances (2016); Langmuir (2017); Adv Elect Materials (2019); Science Advances (2021); Nanoscale Advances (2021); JAP (2022). Highlights by Bloomberg News https://youtu.be/VsUF_CBJq50 (2022); US Patent 10,873,026; US Patent 10,074,819; US Patent 9,673,399.

Anisotropic Piezoresistive Sensors Made with Magnetically Induced Vertically Aligned Carbon Nanotubes/Polydimethylsiloxane.

A piezoresistive material consisting of internal vertically aligned carbon nanotubes acting in concert with an external microdome structure is prepared to obtain a flexible piezoresistive sensor with high anisotropy. Here, we first obtained flexible piezoresistive composites (VCP) with anisotropic properties by inducing the vertical alignment of multiwalled carbon nanotubes in the pressure direction under a weak magnetic field of 0.6 T. Then, the composite with a microdome structure on the surface (m-VCP) was fabricated by a mold with a microstructure to further increase the anisotropy of the composite. The m-VCP microstructure was docked with VCP and placed between two layers of copper foil. With the synergistic effect of vertically aligned carbon nanotubes and the microdome structure, the sensitivity of the flexible sensor in the pressure direction was dramatically increased. In the low-strain range (0-6%), the sensitivity of m-VCP (GF = 9.208) is improved by 49% compared to m-CP and by 86% compared to VCP. The sensor has high anisotropy in the piezoresistive direction and retains good fatigue resistance under fatigue testing for 2000 cycles. This means that the sensor can be used in emerging fields such as human health monitoring, wearable electronics, and intelligent human-computer interaction.

Unidirectional Electron-Tunnelling Flexible PDMS Strain Sensor with Aligned Carbon Nanotubes.

High-aspect-ratio carbon nanotubes can be directly mixed into polymers to create piezoresistive polymers. Reducing the cross-sensitivity and creating unidirectional sensitive sensors can be achieved by aligning the nanotubes before they are cured in the polymer layer. This research presents and characterises this alignment of carbon nanotubes inside polydimethylsiloxane and gives the corresponding strain sensor results. The influence on the alignment method, as well as the field strength, frequency and time is shown. An analytical model is created to investigate the sensor's behaviour and determine the effect of electron-tunnelling in the sensor. A numerical model gives insight into the necessary applied field strength, frequency and time to facilitate alignment in viscous liquids. The experimental data show a two-phase piezoresistive response; first, a linear strain response, after which the more dominant electron-tunnelling piezoresistive phase starts with high gauge factors up to k ≈ 4500 in the preferential direction, depending on the carbon nanotube concentration. Gauge factors in the orthogonal direction remain low (k ≈ 22). Finally, the dynamic stability of the sensors is proven by exposing the sensors to a cyclic strain. Small initial drifts are observed but appear to stabilise after several cycles.

Parameters Affecting Interfacial Assembly and Alignment of Nanotubes.

Tangential flow interfacial self-assembly (TaFISA) is a promising scalable technique enabling uniformly aligned carbon nanotubes for high-performance semiconductor electronics. In this process, flow is utilized to induce global alignment in two-dimensional nematic carbon nanotube assemblies trapped at a liquid/liquid interface, and these assemblies are subsequently deposited on target substrates. Here, we present an observational study of experimental parameters that affect the interfacial assembly and subsequent aligned nanotube deposition. We specifically study the water contact angle (WCA) of the substrate, nanotube ink composition, and water subphase and examine their effects on liquid crystal defects, overall and local alignment, and nanotube bunching or crowding. By varying the substrate chemical functionalization, we determine that highly aligned, densely packed, individualized nanotubes deposit only at relatively small WCA between 35 and 65°. At WCA (< 10°), high nanotube bunching or crowding occurs, and the film is nonuniform, while aligned deposition ceases to occur at higher WCA (>65°). We find that the best alignment, with minimal liquid crystal defects, occurs when the polymer-wrapped nanotubes are dispersed in chloroform at a low (0.6:1) wrapper polymer to nanotube ratio. We also demonstrate that modifying the water subphase through the addition of glycerol not only improves overall alignment and reduces liquid crystal defects but also increases local nanotube bunching. These observations provide important guidance for the implementation of TaFISA and its use toward creating technologies based on aligned semiconducting carbon nanotubes.

Superior flexural, interlaminar- shear and fracture performance of glass fiber/epoxy laminates employing 3-D reinforcement approach: Emphasis on through thickness functionalized CNT alignment

Owing to the absence of z-directional reinforcement in laminated glass/epoxy (GE) composites, their performance under out-of-plane normal and in-plane shear loadings are questionable. This article highlights the importance of using an electric field induced nanotube alignment along the z-direction of the laminate using pristine and functionalized CNTs (CNT and FCNT). Use of aligned FCNTs in the GE composite showed best performance as confirmed from a series of mechanical tests, i.e. flexural properties, interlaminar shear strength (ILSS), mode- I and II interlaminar fracture toughness (ILFT). The key finding of this work includes an enhancement in the critical energy release rate under crack opening mode (i.e. GIC) as high as ∼82% in case of A-0.1F-CNT-GE (0.1 wt% aligned FCNT in GE composite) over the control GE composite. Fractographic study reveals various strengthening and toughening mechanisms responsible for the improved mechanical properties of the composites due to alignment and functionalization of CNTs.

Assembly and Characterization of Length-Sorted, Aligned Boron Nitride/Carbon Nanotube Thin Film Composites Via Slow Vacuum Filtration

Globally aligned single-wall carbon nanotubes (SWCNTs) are a promising, scalable platform for studying fundamental physical phenomena and an important vehicle for optoelectronic device applications. Recent work by Rust et al. [1] has identified nanotube length as an important mediating factor in the degree and scale of SWCNT alignment via slow vacuum filtration (SVF).Building on this work and that of Walker et al. [2,3], we explore the co-assembly of length-sorted SWCNTs and boron nitride nanotubes (BNNTs) atop polycarbonate track-etched membranes. BNNTs have recently gained interest as a chirality-agnostic, wide-bandgap material for encapsulation, insulation, thermal/mechanical robustness, and visible-light transparency, while also having a similar high aspect ratio morphology, making them an exceptional and alignable host matrix for individualized CNT species. To prepare such hybrid assemblies, a polymer-assisted, depletion-based method was first used to length-sort different diameter SWCNT (alkane filled electric-arc, CoMoCAT, metallic-sorted Tuball), and BNNT nanotube populations. Thereafter, we investigated the impacts of tube lengths, relative BN/C fraction, mass loading, and presence of a global director force on the multi-scale assembly behavior. A combination of birefringence microscopy and polarized Raman spectroscopy probed and identified trends in global and local ordering under these conditions.[1] Rust, C., Shapturenka, P., Spari, M., Jin, Q., Li, H., Bacher, A., Guttmann, M., Zheng, M., Adel, T., Hight Walker, A. R., Fagan, J. A., & Flavel, B. S. (2022). The Impact of Carbon Nanotube Length and Diameter on their Global Alignment by Dead-End Filtration. Small (forthcoming).[2] Walker, J. S., Fagan, J. A., Biacchi, A. J., Kuehl, V. A., Searles, T. A., Hight Walker, A. R., & Rice, W. D. (2019). Global Alignment of Solution-Based Single-Wall Carbon Nanotube Films via Machine-Vision Controlled Filtration. Nano Letters, 19(10), 7256–7264.[3] Walker, J. S., Macdermid, Z. J., Fagan, J. A., Kolmakov, A., Biacchi, A. J., Searles, T. A., Walker, A. R. H., & Rice, W. D. (2022). Dependence of Single‐Wall Carbon Nanotube Alignment on the Filter Membrane Interface in Slow Vacuum Filtration. Small, 18, 2105619.

Observations of the synthesis of straight single wall carbon nanotubes directed by electric fields in an Environmental Transmission Electron Microscope

We report here observations in real time of the aligning effect of electric fields during the synthesis of carbon nanotubes in an environmental transmission electron microscope (ETEM). Growths took place using C2H2 as precursor gas at ∼10−4 mbar, a temperature of ∼700°C and within a micro-capacitor incorporated in a specifically-designed heating micro-chip. Individual nanotubes are easily resolved as they appear as extremely straight lines growing parallel to the electric field. These nanotubes are predominantly Single Wall Carbon Nanotubes (SWNTs). Owing to the very good alignment of nanotubes in the object plane of the microscope we can obtain unprecedented excellent determination of the nanotubes’ growth rates and follow them dynamically. Constant growth rates are observed in most cases but other behaviours are observed such as growth rate acceleration. For low applied voltages the growing nanotubes can cross the gap and connect to the opposite electrode although some are destroyed by mechanical failure or during the contact. For high applied fields and positive biasing allowing Field Emission (FE), the growth is limited within the gap as FE can occur during growth leading to new saturation or destruction processes. These different mechanisms are presented as well as the observed balance between electrostatic and adhesion forces.

Joint Theoretical and Experimental Study of Stress Graphitization in Aligned Carbon Nanotube/Carbon Matrix Composites.

Stress graphitization is a unique phenomenon at the carbon nanotube (CNT)-matrix interfaces in CNT/carbon matrix (CNT/C) composites. A lack of fundamental atomistic understanding of its evolution mechanisms and a gap between the theoretical and experimental research have hindered the pursuit of utilizing this phenomenon for producing ultrahigh-performance CNT/C composites. Here, we performed reactive molecular dynamics simulations along with an experimental study to explore stress graphitization mechanisms of a CNT/polyacrylonitrile (PAN)-based carbon matrix composite. Different CNT contents in the composite were considered, while the nanotube alignment was controlled in one direction in the simulations. We observe that the system with a higher CNT content exhibits higher localized stress concentration in the periphery of CNTs, causing alignment of the nitrile groups in the PAN matrix along the CNTs, which subsequently results in preferential dehydrogenation and clustering of carbon rings and eventually graphitization of the PAN matrix when carbonized at 1500 K. These simulation results have been validated by experimentally produced CNT/PAN-based carbon matrix composite films, with transmission electron microscopy images showing the formation of additional graphitic layers converted by the PAN matrix around CNTs, where 82 and 144% improvements of the tensile strength and Young's modulus are achieved, respectively. The presented atomistic details of stress graphitization can provide guidance for further optimizing CNT-matrix interfaces in a more predictive and controllable way for the development of novel CNT/C composites with high performance.

Alignment of multiwalled carbon nanotubes‐reinforced epoxy by a novel shear assisted method in the presence of the electric field

AbstractThe application of multiwall carbon nanotubes (MWCNTs) alignment associated with external field techniques is fairly limited in the industry due to the cost implications of scaling such external fields. To address this problem, a new shear‐assisted method is introduced to increase the effectiveness of MWCNTs alignment techniques using electric field. In addition, the effect of curing temperature of polymer in CNT‐reinforced nanocomposites, is studied on the alignment of MWCNTs using our novel shear‐assisted technique. The results show that increasing the temperature during the curing process of the polymer can help with the alignment of MWCNTs using our shear‐assisted technique. This may be attributed to lower gel‐time of polymer matrix at high temperatures that can prevent agglomeration of the MWCNTs in the matrix. Moreover, fractography of reinforced composites has been studied by scanning electron microscopy to investigate the effects of curing temperature on the alignment of MWCNTs in the epoxy matrix.

Scalable High Tensile Modulus Composite Laminates Using Continuous Carbon Nanotube Yarns for Aerospace Applications.

An approach is established for fabricating high-strength and high-stiffness composite laminates with continuous carbon nanotube (CNT) yarns for scaled-up mechanical tests and potential aerospace structure applications. Continuous CNT yarns with up to 80% degree of nanotube alignment and a unique self-assembled graphitic CNT packing result in their specific tensile strengths of 1.77 ± 0.07 N/tex and an apparent specific modulus of 92.6 ± 3.2 N/tex. Unidirectional CNT yarn reinforced composite laminates with a CNT concentration of greater than 80 wt % and minimal microscale voids are fabricated using filament winding and aerospace-grade resin matrices. A specific tensile strength of up to 1.71 GPa/(g cm-3) and specific modulus of 256 GPa/(g cm-3) are realized; the specific modulus exceeds current state-of-the-art unidirectional carbon fiber composite laminates. The specific modulus of the laminates is 2.76 times greater than the specific modulus of the constituent CNT yarns, a phenomenon not observed in carbon fiber reinforced composites. The results demonstrate an effective approach for fabricating high-strength CNT yarns into composites for applications that require specific tensile modulus properties that are significantly beyond state-of-the-art carbon fiber composites and potentially open an unexplored performance region in the Ashby chart for composite material applications.