2024

Jump to: 2023, 2022, 2021

25 pages, 15545 KiB

Open AccessArticle

Pristine and Coated Carbon Nanotube Sheets—Characterization and Potential Applications

by Prakash Giri, Irwin Gill, Morgan Swensgard, Alexandra Kaiser, Audrey Rust, Brian Stuparyk, Andrew Fisher, Justice Williams, Katie Renoit, Eleanor Kreeb, Corentin Lavenan and Mark J. Schulz

C 2024, 10(1), 17; https://doi.org/10.3390/c10010017 - 09 Feb 2024

Viewed by 1297

Abstract

A carbon nanotube (CNT) sheet is a nonwoven fabric that is being evaluated for use in different textile applications. Several properties of pristine CNT sheets and CNT sheets coated with a polysilazane sealant and coating were measured and compared in the paper. The [...] Read more.

A carbon nanotube (CNT) sheet is a nonwoven fabric that is being evaluated for use in different textile applications. Several properties of pristine CNT sheets and CNT sheets coated with a polysilazane sealant and coating were measured and compared in the paper. The polysilazane coating is used to reduce the shedding of CNT fibers from the sheet when the sheet is in contact with surfaces. Most fabrics show some shedding of fibers during the washing or abrasion of the fabric. This study showed that the coating reduces the shedding of fibers from CNT fabric. The coating also increased the flame resistance of the fabric. The pristine and coated sheets both have low strength but high strain to failure. The pristine and coated CNT sheet densities are 0.48 g/cc and 0.65 g/cc, respectively. The pristine CNT sheet is approximately 27 μ thick. The coated sheet is approximately 24 μ thick. The coating may have densified the sheet, making it thinner. The thickness of the compliant sheets was difficult to measure and is a source of error in the properties. Characterization results are given in this paper. The results are for comparison purposes and not to establish material properties data. Possible applications for CNT sheets are briefly discussed. Full article

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19 pages, 7449 KiB

Open AccessArticle

Continuous Reactive-Roll-to-Roll Growth of Carbon Nanotubes for Fog Water Harvesting Applications

by Jean-Luc Meunier, Jeanne Ouellet, Kaustubh Basu, Alessio Aufoujal, Richard Boudreault and Jason Robert Tavares

C 2024, 10(1), 9; https://doi.org/10.3390/c10010009 - 09 Jan 2024

Viewed by 1475

Abstract

A simple method is presented for the continuous generation of carbon nanotube forests stably anchored on stainless-steel surfaces using a reactive-roll-to-roll (RR2R) configuration. No addition of catalyst nanoparticles is required for the CNT-forest generation; the stainless-steel substrate itself is tuned to generate the [...] Read more.

A simple method is presented for the continuous generation of carbon nanotube forests stably anchored on stainless-steel surfaces using a reactive-roll-to-roll (RR2R) configuration. No addition of catalyst nanoparticles is required for the CNT-forest generation; the stainless-steel substrate itself is tuned to generate the catalytic growth sites. The process enables very large surfaces covered with CNT forests to have individual CNT roots anchored to the metallic ground through primary bonds. Fog water harvesting is demonstrated and tested as one potential application using long CNT-covered wires. The RR2R is performed in the gas phase; no solution processing of CNT suspensions is used, contrary to usual R2R CNT-based technologies. Full or partial CNT-forest coverage provides tuning of the ratio and shape of hydrophobic and hydrophilic zones on the surface. This enables the optimization of fog water harvesters for droplet capture through the hydrophobic CNT forest and water removal from the hydrophilic SS surface. Water recovery tests using small harp-type harvesters with CNT-forest generate water capture of up to 2.2 g/cm²·h under ultrasound-generated fog flow. The strong CNT root anchoring on the stainless-steel surfaces provides opportunities for (i) robustness and easy transport of the composite structure and (ii) chemical functionalization and/or nanoparticle decoration of the structures, and it opens the road for a series of applications on large-scale surfaces, including fog harvesting. Full article

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2023

Jump to: 2024, 2022, 2021

21 pages, 8435 KiB

Open AccessArticle

Synthesis and Processing of Near Infrared—Activated Vitrimer Nanocomposite Films Modified with β-Hydroxyester-Functionalized Multi-Walled Carbon Nanotubes

by Tomás E. Byrne Prudente, Diandra Mauro, Julieta Puig, Facundo I. Altuna, Tatiana Da Ros and Cristina E. Hoppe

C 2023, 9(4), 119; https://doi.org/10.3390/c9040119 - 08 Dec 2023

Viewed by 1468

Abstract

Films of a vitrimer based on the reaction between diglycidylether of bisphenol A and glutaric acid in the presence of 1-methylimidazole were processed using a solvent-based technique. The curing schedule was divided into two steps: first, a soluble linear polymer was formed through [...] Read more.

Films of a vitrimer based on the reaction between diglycidylether of bisphenol A and glutaric acid in the presence of 1-methylimidazole were processed using a solvent-based technique. The curing schedule was divided into two steps: first, a soluble linear polymer was formed through the reaction of the diacid and the diepoxide, and then the crosslinking was induced at a higher temperature via transesterification reactions. This epoxy–acid vitrimer was modified with multi-walled carbon nanotubes (MWCNTs) functionalized with β-hydroxyesters, produced by a robust and straightforward strategy based on a two-phase reaction between oxidized MWCNTs and phenylglycidylether. Nanocomposite vitrimer films were obtained by drop casting a dispersion of the functionalized MWCNTs in the linear polymer/cyclohexanone solution, followed by a thermal treatment. A high degree of dispersion of the carbon nanostructures was attained thanks to the β-hydroxyester functionalization when compared with oxidized MWCNTs. Nanocomposite films showed a significant photothermal effect (reaching 200 °C or above in 30 s) upon NIR light irradiation (850 nm) from a single LED (500 mW/cm²). The released heat was used to activate the shape memory effect and weld and heal the vitrimer matrix, proving the success of this easy strategy for the generation of remotely activated carbon-based vitrimer nanocomposites. Full article

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19 pages, 9149 KiB

Open AccessArticle

Development of CNT-Based Nanocomposites with Ohmic Heating Capability towards Self-Healing Applications in Extrusion-Based 3D Printing Technologies

by Niki Loura, Eleni Gkartzou, Aikaterini-Flora Trompeta, Georgios Konstantopoulos, Panagiotis A. Klonos, Apostolos Kyritsis and Costas A. Charitidis

C 2023, 9(4), 111; https://doi.org/10.3390/c9040111 - 17 Nov 2023

Cited by 1 | Viewed by 1469

Abstract

In the present study, a series of carbon-based nanocomposites based on recycled thermoplastic polyurethane (TPU) matrix and MWCNT fillers synthesized in a laboratory environment were prepared at various loadings and assessed in terms of their functional thermal, dielectric, and rheological properties, as well [...] Read more.

In the present study, a series of carbon-based nanocomposites based on recycled thermoplastic polyurethane (TPU) matrix and MWCNT fillers synthesized in a laboratory environment were prepared at various loadings and assessed in terms of their functional thermal, dielectric, and rheological properties, as well as their ohmic heating capability, for self-healing applications in extrusion-based 3D printing technologies. The synthesis of nanomaterials focused on the production of two different types of carbon nanotubes (CNTs) via the chemical vapor deposition (CVD) method. A comparative assessment and benchmarking were conducted with nanocomposite filaments obtained from commercial nanomaterials and masterbatches with MWCNTs. For all the polymer nanocomposites, samples were prepared at additive contents up to 15 wt.% and filament feedstock was produced via the melt-extrusion process for 3D printing; these were previously characterized by rheological tests. The measurements of thermal and electrical conductivity resulted in a selected composition with promising ohmic heating capability. As a preliminary assessment of the self-healing ability of the above samples, artificial cracks were introduced on the surface of the samples and SEM analysis took place at the crack location before and after applying voltage as a measure of the effectiveness of the material remelting due to the Joule effect. Results indicate a promising material response with a partial restoration of artificial cracks. Full article

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14 pages, 3633 KiB

Open AccessArticle

Effect of Multi-Walled Carbon Nanotubes on the Mechanical and Thermal Properties of Curauá Natural-Fiber-Reinforced Composites

by Jorge S. S. Neto, Daniel K. K. Cavalcanti, Luiz E. da Cunha Ferro, Henrique F. M. de Queiroz, Ricardo A. A. Aguiar and Mariana D. Banea

C 2023, 9(4), 102; https://doi.org/10.3390/c9040102 - 03 Nov 2023

Cited by 2 | Viewed by 1364

Abstract

The main objective of this research centered on investigating the effect of the addition of multi-walled carbon nanotubes (MWCNTs) on the mechanical and thermal properties of curauá-fiber-reinforced composites. The MWCNTs were added either to the fiber surface or into the resin matrix as [...] Read more.

The main objective of this research centered on investigating the effect of the addition of multi-walled carbon nanotubes (MWCNTs) on the mechanical and thermal properties of curauá-fiber-reinforced composites. The MWCNTs were added either to the fiber surface or into the resin matrix as the second reinforcing phase. The MWCNT-modified curauá fibers as well as raw fibers were characterized using a single-fiber tensile test, TGA, and FTIR analysis. Further, different composite samples, namely, pure curauá, (curauá + MWCNTs) + resin and curauá+ (resin + MWCNTs), were manufactured via compression molding and tested to determine their mechanical and thermal properties. Scanning electron microscopy (SEM) analysis was used to examine the surfaces of the tested fibers. It was found that the addition of MWCNTs to the curauá fibers resulted in positive effects (an enhancement in properties was found for the MWCNT-modified fibers and their composites). The addition of MWCNTs also increased the thermal stability of the natural fibers and composites. Full article

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13 pages, 4235 KiB

Open AccessArticle

Piezoresistive Response of Carbon Nanotube Yarn Monofilament Composites under Axial Compression

by Iriana Garcia Guerra, Tannaz Tayyarian, Omar Rodríguez-Uicab and Jandro L. Abot

C 2023, 9(4), 89; https://doi.org/10.3390/c9040089 - 25 Sep 2023

Viewed by 1170

Abstract

The hierarchical structure and microscale dimensions of carbon nanotube yarns (CNTYs) make them great candidates for the development of integrated sensing applications. The change in the electrical resistance of CNTYs due to mechanical strain, known as piezoresistivity, is the principal mechanism in strain [...] Read more.

The hierarchical structure and microscale dimensions of carbon nanotube yarns (CNTYs) make them great candidates for the development of integrated sensing applications. The change in the electrical resistance of CNTYs due to mechanical strain, known as piezoresistivity, is the principal mechanism in strain sensing using CNTYs. While the axial tensile properties of CNTYs have been studied widely, studies on the axial piezoresistive response of CNTYS under compression have been limited due to the complexities associated with the nature of the experiments involving subjecting a slender fiber to compression loading in its axial direction. In this study, the piezoresistive response of a single CNTY embedded into a polymeric resin (CNTY monofilament composite) was investigated under axial compression. The results suggest that the CNTY exhibits a strong piezoresistive response in the axial direction with sensitivity or gauge factor values in the order of 0.4–0.5 for CNTY monofilament composites. The piezoresistive response of the CNTY monofilament composites under compression was compared to that under tension and it was observed that the sensitivity appears to be slightly lower under compression. The potential change in sensitivity between the freestanding CNTY and the CNTY monofilament composite under compression is still unknown. Knowing the axial piezoresistive response of the CNTYs under both tension and compression will enable their use in sensing applications where the yarn undergoes compression including those in aerospace and marine structures, and civil or energy infrastructure. Full article

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22 pages, 6143 KiB

Open AccessArticle

Membranes of Multiwall Carbon Nanotubes in Chitosan–Starch with Mechanical and Compositional Properties Useful in Li-Ion Batteries

by Yoxkin Estévez-Martínez, Enrique Quiroga-González, Erick Cuevas-Yañez, Sergio Durón-Torres, Daniel Alaníz-Lumbreras, Elizabeth Chavira-Martínez, Rubén Posada-Gómez, Jeremias Bravo-Tapia and Víctor Castaño-Meneses

C 2023, 9(3), 87; https://doi.org/10.3390/c9030087 - 08 Sep 2023

Cited by 1 | Viewed by 1416

Abstract

This work reports on membranes of a combination of chitosan–starch with lithium-modified multiwall carbon nanotubes. One of the most important contributions of this article is the functionalization of the surface of multiwall carbon nanotubes by means of an accessible technique that allows for [...] Read more.

This work reports on membranes of a combination of chitosan–starch with lithium-modified multiwall carbon nanotubes. One of the most important contributions of this article is the functionalization of the surface of multiwall carbon nanotubes by means of an accessible technique that allows for high grafting yields of lithium and their incorporation into a polymeric matrix. The natural compounds chitosan and starch were used as a support to embed the nanotubes, forming membranes with good mechanical stability. A thorough characterization via Raman, infrared and X-ray photoelectron spectroscopies, transmission and scanning electron microscopies and dynamic mechanical analysis is presented here, as well as electrochemical characterization. The composition, structure and mechanical stability of the membranes make them viable candidates to be used as anodes sustainable Li-ion batteries. Full article

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16 pages, 10060 KiB

Open AccessArticle

Lightweight Copper–Carbon Nanotube Core–Shell Composite Fiber for Power Cable Application

by Kavitha Mulackampilly Joseph, Kyle Brittingham, Vamsi Krishna Reddy Kondapalli, Mahnoosh Khosravifar, Ayush Arun Raut, Brett David Karsten, Hunter J. Kasparian, Nhat Phan, Arun Kamath, Amjad S. Almansour, Maricela Lizcano, Diana Santiago, David Mast and Vesselin Shanov

C 2023, 9(2), 43; https://doi.org/10.3390/c9020043 - 24 Apr 2023

Cited by 2 | Viewed by 2796

Abstract

The substitution of traditional copper power transmission cables with lightweight copper–carbon nanotube (Cu–CNT) composite fibers is critical for reducing the weight, fuel consumption, and CO₂ emissions of automobiles and aircrafts. Such a replacement will also allow for lowering the transmission power loss [...] Read more.

The substitution of traditional copper power transmission cables with lightweight copper–carbon nanotube (Cu–CNT) composite fibers is critical for reducing the weight, fuel consumption, and CO₂ emissions of automobiles and aircrafts. Such a replacement will also allow for lowering the transmission power loss in copper cables resulting in a decrease in coal and gas consumption, and ultimately diminishing the carbon footprint. In this work, we created a lightweight Cu–CNT composite fiber through a multistep scalable process, including spinning, densification, functionalization, and double-layer copper deposition. The characterization and testing of the fabricated fiber included surface morphology, electrical conductivity, mechanical strength, crystallinity, and ampacity (current density). The electrical conductivity of the resultant composite fiber was measured to be 0.5 × 10⁶ S/m with an ampacity of 0.18 × 10⁵ A/cm². The copper-coated CNT fibers were 16 times lighter and 2.7 times stronger than copper wire, as they revealed a gravimetric density of 0.4 g/cm³ and a mechanical strength of 0.68 GPa, suggesting a great potential in future applications as lightweight power transmission cables. Full article

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15 pages, 2833 KiB

Open AccessFeature PaperArticle

Nanocomposites Produced with the Addition of Carbon Nanotubes Dispersed on the Surface of Cement Particles Using Different Non-Aqueous Media

by Vanessa Vilela Rocha, Bruno Athaíde Bacelar, Isabela Domingues Coelho and Péter Ludvig

C 2023, 9(1), 36; https://doi.org/10.3390/c9010036 - 22 Mar 2023

Viewed by 1472

Abstract

The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted [...] Read more.

The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted to guarantee those gains. Among the methods applied to produce such composites is the dispersion of CNTs on the surface of anhydrous cement particles using non-aqueous suspensions such as acetone, ethanol, or isopropanol. Even though those non-aqueous media have been individually studied by researchers, comparisons of the efficiency of CNTs dispersion was not found in the literature. Therefore, as a novelty, the present article aims to analyze the influence of the addition of the multi-walled CNTs dispersed in the cited three types of non-aqueous suspensions on the cement paste’s electrical and mechanical properties. Pastes containing 0%, 0.5%, and 1.0% of CNTs were prepared on the surface of anhydrous cement particles using a pre-dispersion technique based on simultaneous sonication and mechanical agitation in the three cited media. Tests to determine electric-volumetric resistivity, compressive strength, and splitting tensile strength were performed. It was observed that acetone dispersion decreases the cement paste’s electrical resistivity, even without the addition of CNTs. The cementitious composites with CNTs demonstrated increased mechanical strength (both compressive and tensile) using all three dispersion media. Statistical analysis (analysis of variance—ANOVA—and Tukey’s Test) was performed to evaluate the significance of the results. Full article

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13 pages, 5491 KiB

Open AccessArticle

Highly Selective Detection of Hydrogen Sulfide by Simple Cu-CNTs Nanocomposites

by Nahida Musayeva, Hadiya Khalilova, Bakhtiyar Izzatov, Giovanna Trevisi, Shahla Ahmadova and Muhammad Alizada

C 2023, 9(1), 25; https://doi.org/10.3390/c9010025 - 24 Feb 2023

Cited by 3 | Viewed by 1516

Abstract

The presented work is devoted to the preparation of nanocomposites based on multiwall carbon nanotubes (MWCNTs) and copper (Cu) nanoparticles by a simple chemical method, and to study their sensing properties to hydrogen sulfide (H₂S) gas. The Cu decorated multiwall carbon [...] Read more.

The presented work is devoted to the preparation of nanocomposites based on multiwall carbon nanotubes (MWCNTs) and copper (Cu) nanoparticles by a simple chemical method, and to study their sensing properties to hydrogen sulfide (H₂S) gas. The Cu decorated multiwall carbon nanotubes (MWCNTs/Cu) were prepared by the deposition of very thin Cu layers on the pristine and functionalized multiwall carbon nanotubes (f-MWCNTs) using both physical (electron beam evaporation (EBE)) and chemical (electrochemical deposition) methods. MWCNTs/Cu prepared in the two above-mentioned ways, their sensing properties were studied, and the results were comparatively analyzed. The effect of the chemical functionalization of MWCNTs by oxygen-containing groups on the sensing properties of these f-MWCNT/Cu nanocomposites has been investigated. All the prepared sensors demonstrated high sensitivity and selectivity to H₂S in the air at room temperature. The f-MWCNT/Cu structure obtained by the chemical method demonstrated about 5 times (~400%) higher sensitivity (∆R/R₀) to H₂S gas compared to the similar structure obtained by the physical method. The temperature effect on sensory characteristics (response and self-recovery time) of the f-MWCNTs/Cu structure was also studied. Full article

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18 pages, 3322 KiB

Open AccessArticle

Physical Processes Occurring in Dispersed Media with Carbon Nanomaterials under the Influence of Ultrasonification

by Svetlana Obukhova and Evgenii Korolev

C 2023, 9(1), 18; https://doi.org/10.3390/c9010018 - 31 Jan 2023

Viewed by 1474

Abstract

The up-to-date carbon nanoparticle application in materials science and composites is mostly represented by controlling of different methods of structure formation including incorporation of nanomaterials or nano-modifiers. The efficiency of such methods depends on disagglomeration and the distribution degree of the carbon nanoparticle [...] Read more.

The up-to-date carbon nanoparticle application in materials science and composites is mostly represented by controlling of different methods of structure formation including incorporation of nanomaterials or nano-modifiers. The efficiency of such methods depends on disagglomeration and the distribution degree of the carbon nanoparticle within a dispersion medium, which are critical parameters to produce a composite with improved performance. At the same time, common approaches such as a surface activation or using surfactants do not guarantee a homogeneous dispersion of carbon nanoparticles. This research reports on a theoretical analysis of physical processes which take place during the ultrasonic treatment which is a widely used method for dispersion of nanomaterials. The experimental data demonstrate an efficiency of the proposed method and prove the theoretical assumptions. The theoretical analysis performed in this study can be applied to implement and scale-up the process using sonicators. It was established that ultrasonic treatment has a more intensive effect in an organic hydrocarbon medium. So, in industrial oil, the heating rate from ultrasonification is 20 °C/min, in residual selective purification extract, it is 33 °C/min. For aqueous systems, the heating rate from ultrasonification is significantly lower and amounts to 2 °C /min for suspensions with Sulfanol and 11 °C/min for suspensions with ViscoCrete 2100. It was established that in the studied dispersed systems (aqueous solutions with surfactants and organic medium), there is no directly proportional dependence of the amount of heating of suspensions on the duration of ultrasound dispersion (USD), which is caused by ultrasonic dispersion not under adiabatic conditions, as well as the dependence of absorption coefficient of ultrasonic energy for dispersed systems on parameters of system structure. Full article

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2022

Jump to: 2024, 2023, 2021

27 pages, 2922 KiB

Open AccessArticle

Applicability and Limitations of Ru’s Formulation for Vibration Modelling of Double-Walled Carbon Nanotubes

by Matteo Strozzi

C 2022, 8(4), 59; https://doi.org/10.3390/c8040059 - 02 Nov 2022

Cited by 1 | Viewed by 1350

Abstract

In this paper, a comparison is conducted between two different formulations of the van der Waals interaction coefficient between layers, as applied to the vibrations of double-walled carbon nanotubes (DWCNTs); specifically, the evaluation of the natural frequencies is achieved through Ru’s and He’s [...] Read more.

In this paper, a comparison is conducted between two different formulations of the van der Waals interaction coefficient between layers, as applied to the vibrations of double-walled carbon nanotubes (DWCNTs); specifically, the evaluation of the natural frequencies is achieved through Ru’s and He’s formulations. The actual discrete DWCNT is modelled by means of a couple of concentric equivalent continuous thin cylindrical shells, where Donnell shell theory is adopted to obtain strain-displacement relationships. In order to take into account the chirality effect of DWCNT, an anisotropic elastic shell model is considered. Simply supported boundary conditions are imposed and the Rayleigh–Ritz method is used to obtain approximate natural frequencies and mode shapes. A parametric analysis considering different values of diameters and numbers of waves along longitudinal and circumferential directions is performed by adopting Ru’s and He’s formulations. From the comparisons, it is evident that Ru’s formulation provides unsatisfactory results for relatively low values of diameters and relatively high numbers of circumferential waves with respect to the more accurate He’s formulation. This behaviour is observed for every number of longitudinal half-waves. Therefore, Ru’s formulation cannot be used for the vibration modelling of DWCNTs in a large range of diameters and wavenumbers. Full article

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11 pages, 5260 KiB

Open AccessArticle

Stability of Carboxyl-Functionalized Carbon Nanotubes in Simulated Cement Pore Solution and Its Effect on the Compressive Strength and Porosity of Cement-Based Nanocomposites

by Laura Silvestro, Geannina Terezinha Dos Santos Lima, Artur Spat Ruviaro and Philippe Jean Paul Gleize

C 2022, 8(3), 39; https://doi.org/10.3390/c8030039 - 19 Jul 2022

Cited by 4 | Viewed by 2184

Abstract

The application of carbon nanotubes to produce cementitious composites has been extensively researched. However, the dispersion of this nanomaterial remains a technical limitation for its use. Thus, initially, this study assessed the stability of carboxyl-functionalized CNT on aqueous suspensions and simulated cement pore [...] Read more.

The application of carbon nanotubes to produce cementitious composites has been extensively researched. However, the dispersion of this nanomaterial remains a technical limitation for its use. Thus, initially, this study assessed the stability of carboxyl-functionalized CNT on aqueous suspensions and simulated cement pore solution for 6 h through UV–visible spectroscopy. Subsequently, a CNT content of 0.1% by cement weight was incorporated into the cement pastes, and the compressive strength after 7, 14, 28, and 91 days was evaluated. In addition, the porosity of the CNT cementitious composites at 28 days of hydration was investigated by mercury intrusion porosimetry (MIP), and the microstructure was evaluated via scanning electron microscopy (SEM). The simulated cement pore solution’s alkaline environment affects the CNT stability, progressively reducing the dispersed CNT concentration over time. CNT reduced the cementitious matrix pores < 50 nm by 8.5%; however, it resulted in an increase of 4.5% in pores > 50 nm. Thus, CNT incorporation did not significantly affect the compressive strength of cement pastes. SEM results also suggested a high porosity of CNT cementitious composites. The CNT agglomeration trend in an alkaline environment affected the CNT performance in cement-based nanocomposites. Full article

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17 pages, 5184 KiB

Open AccessArticle

Digital Synthesis of Realistically Clustered Carbon Nanotubes

by Bryan T. Susi and Jay F. Tu

C 2022, 8(3), 34; https://doi.org/10.3390/c8030034 - 22 Jun 2022

Cited by 3 | Viewed by 2397

Abstract

A computational approach for creating realistically structured carbon nanotubes is presented to enable more accurate and impactful multi-scale modeling and simulation techniques for nanotube research. Much of the published literature to date involving computational modeling of carbon nanotubes simplifies their structure as being [...] Read more.

A computational approach for creating realistically structured carbon nanotubes is presented to enable more accurate and impactful multi-scale modeling and simulation techniques for nanotube research. Much of the published literature to date involving computational modeling of carbon nanotubes simplifies their structure as being long and straight, and often existing as isolated individual nanotubes. However, imagery of nanotubes has shown over several decades that nanotubes agglomerate together and exhibit looping and curvature due both to inter- and intra-nanotube attraction. The research presented in this paper leverages multi-scale simulations consisting of a simple bead-spring model for initial nanotube relaxation followed by a differential geometry approach to create an atomic representation of carbon nanotubes, and then finalized with molecular dynamics simulations using the Tersoff potential model for carbon that allows dynamic bonding and cleavage. The result is atomically accurate representations of carbon nanotubes that exist as single nanotubes, or as clusters of multiple nanotubes. The presented approach is demonstrated using (5,5) single-walled carbon nanotubes. The synthesized nanotubes are shown to relax into the curving and looping structures observed in transmission or scanning electron microscopy, but also exhibit nano-scale defects due to buckling, crimping, and twisting that are resolved during the molecular dynamics simulations. These features locally compromise the desired strength characteristics of nanotubes and therefore the presented procedure will enable more accurate modeling and simulation of nanotubes in subsequent research by representing them less as the theoretically straight and independent entities, but as realistically imperfect. Full article

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9 pages, 1751 KiB

Open AccessArticle

Plasma-Enhanced Carbon Nanotube Fiber Cathode for Li-S Batteries

by Yanbo Fang, Yu-Yun Hsieh, Mahnoosh Khosravifar, Paa Kwasi Adusei, Sathya Narayan Kanakaraj, Bely Stockman, Vamsi Krishna Reddy Kondapalli and Vesselin Shanov

C 2022, 8(2), 30; https://doi.org/10.3390/c8020030 - 22 May 2022

Viewed by 2786

Abstract

Fiber-shaped batteries have attracted much interest in the last few years. However, a major challenge for this type of battery is their relatively low energy density. Here, we present a freestanding, flexible CNT fiber with high electrical conductivity and applied oxygen plasma-functionalization, which [...] Read more.

Fiber-shaped batteries have attracted much interest in the last few years. However, a major challenge for this type of battery is their relatively low energy density. Here, we present a freestanding, flexible CNT fiber with high electrical conductivity and applied oxygen plasma-functionalization, which was successfully employed to serve as an effective cathode for Li-S batteries. The electrochemical results obtained from the conducted battery tests showed a decent rate capability and cyclic stability. The cathode delivered a capacity of 1019 mAh g⁻¹ at 0.1 C. It accommodated a high sulfur loading of 73% and maintained 47% of the initial capacity after 300 cycles. The demonstrated performance of the fiber cathode provides new insights for the designing and fabrication of high energy density fiber-shaped batteries. Full article

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18 pages, 1793 KiB

Open AccessArticle

Engineering of Nanostructured Carbon Catalyst Supports for the Continuous Reduction of Bromate in Drinking Water

by João M. Cunha Bessa da Costa, José R. Monteiro Barbosa, João Restivo, Carla A. Orge, Anabela Nogueira, Sérgio Castro-Silva, Manuel F. Ribeiro Pereira and Olívia S. Gonçalves Pinto Soares

C 2022, 8(2), 21; https://doi.org/10.3390/c8020021 - 22 Mar 2022

Cited by 3 | Viewed by 3184

Abstract

Recent works in the development of nanostructured catalysts for bromate reduction in drinking water under hydrogen have highlighted the importance of the properties of the metallic phase support in their overall performance. Since most works in catalyst development are carried out in powder [...] Read more.

Recent works in the development of nanostructured catalysts for bromate reduction in drinking water under hydrogen have highlighted the importance of the properties of the metallic phase support in their overall performance. Since most works in catalyst development are carried out in powder form, there is an overlooked gap in the correlation between catalyst support properties and performance in typical continuous applications such as fixed bed reactors. In this work, it is shown that the mechanical modification of commercially available carbon nanotubes, one of the most promising supports, can significantly enhance the activity of the catalytic system when tested in a stirred tank reactor, but upon transition to a fixed bed reactor, the formation of preferential pathways for the liquid flow and high pressure drops were observed. This effect could be minimized by the addition of an inert filler to increase the bed porosity; however, the improvement in catalytic performance when compared with the as-received support material was not retained. The operation of the continuous catalytic system was then optimized using a 1 wt.% Pd catalyst supported on the as-received carbon nanotubes. Effluent and hydrogen flow rates as well as catalyst loadings were systematically optimized to find an efficient set of parameters for the operation of the system, regarding its catalytic performance, capacity to treat large effluent flows, and minimization of catalyst and hydrogen requirements. Experiments carried out in the presence of distilled water as a reaction medium demonstrate that bromate can be efficiently removed from the liquid phase, whereas when using a real water matrix, a tendency for the deactivation of the catalyst over time was more apparent throughout 200 flow passages over the catalytic bed, which was mostly attributed to the competitive adsorption of inorganic matter on the catalyst active centers, or the formation of mineral deposits blocking access to the catalyst. Full article

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9 pages, 3449 KiB

Open AccessArticle

From Waste Plastics to Carbon Nanotube Audio Cables

by Varun Shenoy Gangoli, Tim Yick, Fang Bian and Alvin Orbaek White

C 2022, 8(1), 9; https://doi.org/10.3390/c8010009 - 25 Jan 2022

Cited by 3 | Viewed by 4133

Abstract

Carbon nanotubes (CNTs) have long been at the forefront of materials research, with applications ranging from composites for increased tensile strength in construction and sports equipment to transistor switches and solar cell electrodes in energy applications. There remains untapped potential still when it [...] Read more.

Carbon nanotubes (CNTs) have long been at the forefront of materials research, with applications ranging from composites for increased tensile strength in construction and sports equipment to transistor switches and solar cell electrodes in energy applications. There remains untapped potential still when it comes to energy and data transmission, with our group having previously demonstrated a working ethernet cable composed of CNT fibers. Material composition, electrical resistance, and electrical capacitance all play a strong role in the making of high-quality microphone and headphone cables, and the work herein describes the formation of a proof-of-concept CNT audio cable. Testing was done compared to commercial cables, with frequency response measurements performed for further objective testing. The results show performance is on par with commercial cables, and the CNTs being grown from waste plastics as a carbon source further adds to the value proposition, while also being environmentally friendly. Full article

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2021

Jump to: 2024, 2023, 2022

11 pages, 1944 KiB

Open AccessArticle

Prediction of the Near-Infrared Absorption Spectrum of Single-Walled Carbon Nanotubes Using a Bayesian Regularized Back Propagation Neural Network Model

by Takao Onishi, Yuji Matsukawa, Yuto Yamazaki and Daisuke Miyashiro

C 2021, 7(4), 80; https://doi.org/10.3390/c7040080 - 25 Nov 2021

Cited by 1 | Viewed by 2632

Abstract

DNA-wrapped single-walled carbon nanotubes (DNA-SWCNTs) in stable dispersion are expected to be used as biosensors in the future, because they have the property of absorption of light in the near infrared (NIR) region, which is safe for the human body. However, this practical [...] Read more.

DNA-wrapped single-walled carbon nanotubes (DNA-SWCNTs) in stable dispersion are expected to be used as biosensors in the future, because they have the property of absorption of light in the near infrared (NIR) region, which is safe for the human body. However, this practical application requires the understanding of the DNA-SWCNTs’ detailed response characteristics. The purpose of this study is to predict, in detail, the response characteristics of the absorption spectra that result when the antioxidant catechin is added to oxidized DNA-SWCNTs, from a small amount of experimental data. Therefore, in the present study, we predicted the characteristics of the absorption spectra of DNA-SWCNTs using the Bayesian regularization backpropagation neural network (BRBPNN) model. The BRBPNN model was trained with the catechin concentration and initial absorption peaks as inputs and the absorption spectra after catechin addition as outputs. The accuracy of the predicted absorption peaks and wavelengths after the addition of catechin, as predicted by the BRBPNN model, was within 1% of the error of the experimental data. By inputting the catechin concentrations under hundreds of conditions into this BRBPNN model, we were able to obtain detailed prediction curves for the absorption peaks. This method has the potential to help to reduce the experimental costs and improve the efficiency of investigating the properties of high-cost materials such as SWCNTs. Full article

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