Different Types Of Carbon Nanotubes Research Articles

The influence of the carbon nanofiller in the PDMS-based composites on the strain resistive effect

In this study flexible polymer nanocomposite material with different types of carbon nanotubes (CNTs) (single-walled CNT [SWCNT] or multi-walled CNT [MWCNT]) has been obtained for use in stretchable elements of flexible structures. The features of electrically conductive nanostructures and their distribution in the nanocomposite material have been studied using Raman spectrometer and scanning electron microscope, respectively. Setup for studying the functional characteristics of the nanocomposite material based on a testing machine has been developed. The setup ensures simultaneous measurement of the electrical resistance of the nanocomposite material under cyclic tension. The ultimate tensile strength of the polymer composite under 25% tension with different electrically conductive nanostructures has been determined. It has been exposed for a sample with MWCNT, the ultimate tensile strength is significantly lower. It has been revealed that the highest tensile strength had been achieved in composites at about 0.37 MPa. The strain sensitivity (gauge factor [GF]) of polydimethylsiloxane (PDMS)/MWCNT has higher GF value compared to PDMS/SWCNT. This shows a higher potential for using them as fillers for creating sensor systems based on nanocomposite conductive materials.

Interchangeable films made from cellulose acetate and different types of carbon nanotubes with humidity sensing capabilities

Interchangeable films made from cellulose acetate and different types of carbon nanotubes with humidity sensing capabilities

Impact of Winkler-Pasternak foundation parameters on the buckling behavior of composite plates reinforced with FG-CNT in a parabolic distribution

The incorporation of carbon nanotubes (CNT) into a polymer matrix has opened up exciting possibilities for creating Nano-composite materials with exceptional mechanical properties. In this study, the buckling behavior of a reinforced polymer plate mixed with CNTs is investigated. Various factors, such as the plate’s shape and the elastic base, are examined for their effects on behavior. The investigation is grounded in scientific rigor, drawing upon several theories that address plate behavior. Specifically, the high-order theory, which accounts for transverse shear effects and the parabolic distribution of transverse shear stresses across the plate thickness, is employed. By analyzing the critical buckling load, the interaction between different types of carbon nanotubes within the polymer matrix and the elastic medium is explored. The model’s governing equations, derived from Hamilton’s principle, allow for the prediction of the critical loads associated with axial compression buckling. Notably, it is found that the parabolic distribution, coupled with the Winkler—Pasternak elastic foundation, renders the plate less flexible compared to scenarios without an elastic foundation. This insight leads to a crucial enhancement in the critical buckling load. The significance of incorporating carbon nanotubes in polymer matrices to achieve nanocomposite materials with exceptional properties is underscored. The scientific foundation upon which this study rests provides valuable insights for designing robust and efficient structures.

Enhancement of mechanical and electrical properties of copper matrix composites by different types of carbon nanotubes

Copper-based composites with carbon nanotubes (CNTs) as the reinforcing phase possess excellent comprehensive mechanical and electrical properties and have received widespread attention in the electronics industry in recent years. However, a handful of studies concerns CNTs reinforced copper matrix composites with different wall layers. In this study, multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) were selected. An improved molecular-level blending method was exploited to produce copper matrix composites reinforced by MWCNTs and SWCNTs in our study. The characterization results showed that the copper coated MWCNTs and SWCNTs were evenly distributed in the copper matrix and ensured the connection structure tightly between CNTs as heterogeneous strengthening factors and the copper matrix. Meanwhile, in the mechanical property test, the MWCNTs/Cu composite material had the highest tensile strength (262.5 MPa), which was 23.6 % higher than pure copper and 12.6 % higher than the SWCNTs/Cu composite materials. In addition, in the electrical performance test, MWCNTs/Cu and SWCNTs/Cu composites all possessed excellent electrical conductivity, 95 % IACS and 96 % IACS, respectively. The research work in this paper can be extended to the development of ultra-light copper and copper alloy electronic devices and provide a reference for future research on CNTs augmented metal matrix composites.

Apoptosis as a mechanism of human respiratory cell death upon exposure to carbon nanotubes

Introduction. Carbon nanotubes (CNTs) are a group of promising nanomaterials for industrial and biomedical applications. There has been shown influence of the physicochemical characteristics of CNTs on the toxic effects, including the ability to cause DNA damage and induce apoptosis. In this study, there was carried out a comparative assessment of pro-apoptotic effects under exposure to single-walled and multi-walled CNTs produced in Russia on human respiratory cells.
 Materials and methods. Human bronchial epithelial cells BEAS-2B, alveolar epithelial cells A549, and lung fibroblasts MRC5-SV40 were exposed to pristine and purified TUBALLTM SWCNTs and Taunit-M MWCNTs. In cells exposed to 4 concentrations (100, 50, 0.03, 0.0006 μg/ml) of all types of CNTs for 72 hours, the level of mRNA of the P53, BAX and BCL2 genes, as well as the level of reactive oxygen species were assessed.
 Results. All types of CNTs initiated apoptosis in human respiratory epithelial cells BEAS-2B and A549, but not in MRC5-SV40 lung fibroblasts. BEAS-2B were more sensitive to the effects of MWCNTs, while A549 were more sensitive to pristine SWCNTs. Apoptosis was initiated at low concentrations, including those corresponding to industrial exposures. The mechanism of oxidative stress could act as a factor in triggering apoptosis in lung epithelial cells.
 Limitations. Relatively short (72 hours) cell incubation time and the use of 2D cell models that do not consider real cell interactions.
 Conclusion. There were revealed differences in the mechanisms of initiation of the internal pathway of apoptosis and sensitivity to different types of CNTs depending on the type of epithelial cells. Comparative analysis of the initiation of apoptosis by different types of CNTs has shown that there are differences in potential target cells and toxic mechanisms, which should be considered in further studies.

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

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.

Thermo-hydraulic performance of nanofluids composed of functionalized MWCNT

The nanofluids can be utilized as the potential candidates for reducing wear between two metal surfaces. In this work, the characterization and rheological behavior of the ionic liquid 1-ethyl, 3-methylimidazolium dicyanamide had been performed, and its dispersions with different types of carbon nanotubes were compared. It was determined that the viscous behavior of nanofluids was in steady-state shear flow. Then, the study of tribology was performed to study the behavior of the dispersions as a lubricant. Particularly, AISI 316L stainless was used as the specimen considering its potential application in a number of machine parts. Hence, the wear behaviour of the nanofluid was studied by using them as the lubricant 0n AISI 316L steel surfaces. The specimen showed the better thermo-hydraulic performance, since its increments for the convective coefficient were higher.

On isobaric heat capacity of ionanofluids with carbon nanotubes – An experimental study

Ionanofluids (INFs) are defined as ionic liquids (ILs) with therein dispersed nanoparticles. The addition of nanoparticles results in an increase in the thermal conductivity of INFs. In terms of specific isobaric heat capacity (cp) this influence is not yet clear due to contradictory results published up to date. In this work, we assessed the influence of carbon nanotubes (CNTs) on the cp of INFs by means of DSC. We selected 13 different types of ILs and two mixtures of them as the base for INFs. 9 different types of CNTs were chosen: (singlewalled carbon nanotubes) SWCNTs, helical CNTs, Nanocyl multiwalled carbon nanotubes (MWCNTs) and in-house 16h MWCNTs, MWCNTs functionalized with carboxylic groups (COOH), hydroxylic groups (OH), C18n-alkyl chain or polyethylene glycol (PEG). Functionalized MWCNTs have never been investigated in terms of the cp of INFs. A total of 43 INFs were obtained and studied. The influence of CNTs on the cp of INFs was critically analyzed with consideration to the cp of base liquid and its agreement with data available in the literature, and with consideration to measurement uncertainty. Also, the cp of some pristine CNTs (as a bulk material), namely Nanocyl MWCNTs and in-house 16h MWCNTs, was examined. In the most of systems, the addition of CNTs did not affect the cp of INFs. In the others, the effects were minor and not greater than 3.1 %. In the end, the model proposed to estimate the cp of nanofluid, including the existence of nanolayer of IL on the CNT, was critically examined.

Evaluating the Cytotoxicity of Monolayered and Multilayered Carbon Nanotubes on Three Different Human Cell Lines.

Nanotechnology and nanobiotechnology have emerged as novel technologies for the production and application of nanoscale materials in different pharmaceutical, medical, and biological fields. Besides, there are a bunch of recently published patents in this field. Although Carbon Nanotubes (CNTs) have various advantages and can be applied for a wide variety of purposes, their toxicity on humans is a matter of concern. This study aimed to evaluate six different types of CNTs, including pristine, carboxylated, and hydroxylated single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) on three human cell lines. MTT assay was employed to assess the cytotoxicity of six types of CNTs, including pristine, carboxylated, and hydroxylated forms of SWCNTs and MWCNTs on three different human cell lines. The findings of the MTT assay showed that the six different types of CNTs (100- 600 μg/mL) exhibited different levels of cytotoxicity on the three human cell lines. The observed trend presented dose-dependent cytotoxicity on the three studied cell lines, including pulmonary, skin, and gastrointestinal cell lines. SWCNT-COOH and MWCNTs accounted for the lowest cell viability in the three human cell lines. In conclusion, researchers and industrial workers are recommended to be cautious while working with different types of CNT because all their toxicity dimensions have not been determined yet.

Encapsulation of Carbon Nanotubes by Styrene and Butyl Acrylate Particles via Suspension Polymerization for Polymerized Toner Applications.

Electrophotographic printing and copying processes primarily use toner, which is a mixture of colorant, polymer, and additives. Toner can be made using traditional mechanical milling techniques or more contemporary chemical polymerization techniques. Suspension polymerization provides spherical particles with less stabilizer adsorption, homogeneous monomers, higher purity, and easier control of the reaction temperature. In contrast to these advantages, however, the particle size resulting from suspension polymerization is too large for toner. To overcome this disadvantage, devices such as high-speed stirrers and homogenizers can be used to reduce the size of the droplets. This research investigated the use of carbon nanotubes (CNTs) instead of carbon black as the pigment in toner development. We succeeded in achieving a good dispersion of four different types of CNT, specifically modified with NH2 and Boron or unmodified with long or short chains in water rather than chloroform, using sodium n-dodecyl sulfate as a stabilizer. We then performed polymerization of the monomers styrene and butyl acrylate in the presence of the different CNT types and found that the best monomer conversion and largest particles (in the micron range) occurred with CNTs modified with boron. The insertion of a charge control agent into the polymerized particles was achieved. Monomer conversion of over 90% was realized with all concentrations of MEP-51, whereas conversion was under 70% with all concentrations of MEC-88. Furthermore, analysis with dynamic light scattering and scanning electron microscopy (SEM) indicated that all polymerized particles were in the micron size range, suggesting that our newly developed toner particles were less harmful and environmentally friendly products than those typically and commercially available. The SEM micrographs clearly showed good dispersion and attachment of the CNTs on the polymerized particles (no CNT aggregation was found), which has never been published before.

Chemical Oxidation and Characterization of Carbon Nanotubes of Different Types for Improving the Efficiency of REE Preconcentration for Their Subsequent Determination in Geological Samples

Various methods for the oxidation of different types of carbon nanotubes (CNTs) in nitric acid and a mixture of nitric and sulfuric acids at various temperatures and durations of exposure are studied. Oxidation conditions that provide the high sorption activity of sorbents with respect to REE are found. Oxidized CNTs are characterized by acid-base titration and scanning electron microscopy, and the electrokinetic (ζ) potential of nanotube suspensions is determined as a function of pH. The elemental composition of CNTs is determined by ICP MS/AES methods. The sorption capacity of the oxidized CNTs with respect to a wide range of elements is determined. Their unique selectivity with respect to REE is revealed. A possibility of using oxidized CNTs for the efficient sorption preconcentration of REE with the aim to determine their ultralow concentrations in rocks is proved.

Molecular modeling investigation on mechanism of diazinon pesticide removal from water by single- and multi-walled carbon nanotubes

In this study, the mechanism of diazinon adsorption on single-walled carbon nanotubes (SWNTs), as well as multi-walled carbon nanotubes (MWNTs), was investigated using molecular modelling. Determination of the lowest energy sites of different types of carbon nanotubes (CNTs) was demonstrated. The adsorption site locator module was used for this purpose. It was found that the 5-walled CNTs are the best MWNTs for diazinon elimination from water due to their higher interactions with diazinon. In addition, the adsorption mechanism in SWNT and MWNTs was determined to be wholly adsorption on the lateral surface. It is because the geometrical size of diazinon molecules is larger than the inner diameter of SWNT and MWNTs. Furthermore, the contribution of diazinon adsorption on the 5-wall MWNTs was the highest, for the lowest diazinon concentration in the mixture.

Evaluation of the impact of industrial single-walled and multi-walled carbon nanotubes on human respiratory tract epithelial cells

Introduction. In the present study, a comparative assessment of the toxic effects of industrial single-walled and multi-walled carbon nanotubes (SWCNT and MWCNT) at doses corresponding to industrial exposures on BEAS-2B and A549 cells was carried out. Materials and methods. The size distribution of SWCNT and MWCNT agglomerates in dispersions was estimated by dynamic light scattering and transmission electron microscopy. Cytotoxicity was assessed using a MTS test and LDH assay. The interaction of CNTs with cells was visualized using dark-field and transmission electron microscopy. Results. Cytotoxic effects of pristine SWCNT and MWCNT in concentrations of 50-200 μg/ml and purified SWCNT in the range of 25-200 μg/ml were found in BEAS-2B cells. SWCNT and MWCNT were found to penetrate into the cytoplasm of both BEAS-2B and A549 cells, while MWCNT are more often revealed in the intracellular content as vacuolized clusters, and single SWCNT and agglomerates are visualized in the cytoplasm without a tendency to vacuolization. Limitations. CNT were introduced into cells in the form of dispersions, where both single nanotubes and their agglomerates were found. The calculation of CNT concentrations for introduction into cells was based on computer simulation. Conclusion. Further study of the mechanisms of cytotoxic and genotoxic effects of different types of carbon nanotubes (CNT) may contribute to the identification of MWCNT and SWCNT specific effects on the cells of the respiratory system to develop methodological approaches to the safe use of CNT.

Analysis of carbon nanotube for low power nano electronics applications

The implementation of nanoelectronic circuits depends on technologies such as Complementary Metal-Oxide Semiconductor (CMOS) or Bipolar CMOS (BICMOS), and the length of the channel can be reduced up to a certain limit. Due to the generation of various errors nanomaterials can be an alternative solution for circuit design. In the field of nanotechnology, Carbon Nanotubes (CNTs) have become a notable and remarkable invention. Their structure is very similar to that of graphite, and its small size, lightweight, high strength, and good conductivity make them ideal building blocks for future technologies. CNTs hold great promise for being the catalyst for the next technological revolution. Today, a broad range of processes is available to produce various types of CNTs, depending on the rolling times of graphite sheets. This review paper sheds light on the different types of CNTs, their properties, methods of synthesis such as arc discharge and chemical vapor deposition, and their applications. To achieve this goal, this paper provides a review that aims to define the state-of-the-art in this field from a novel and unified perspective while elaborating insights of current developments and emerging trends.

Microstructure and Electrical Conductivity of Cement Paste Reinforced with Different Types of Carbon Nanotubes.

Over the last few years, the addition of small amounts of carbon nanotubes (CNTs) to construction materials has become of great interest, since it enhances some of the mechanical, electrical and thermal properties of the cement. In this sense, single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs, respectively) can be incorporated into cement to achieve the above-mentioned improved features. Thus, the current study presents the results of the addition of SWCNTs and MWCNTs on the microstructure and the physical properties of the cement paste. Density was measured through He pycnometry and the mass change was studied by thermogravimetric analysis (TGA). The microstructure and the phases were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Finally, the electrical conductivity for different CNT concentrations was measured, and an exponential increase of the conductivity with concentration was observed. This last result opens the possibility for these materials to be used in a high variety of fields, such as space intelligent systems with novel electrical and electronic applications.

Comparison of compressive fatigue performance of cementitious composites with different types of carbon nanotube

The compressive fatigue performance of cementitious composites largely depends on the generation and connection of fatigue nano/micro-cracks in the composites. These types of cracks are beyond the scope that traditional fibers can restrain, but can be effectively eliminated and inhibited by incorporating nano-materials, especially those with fiber shape, such as carbon nanotube (CNT). Unfortunately, the effect of CNT and its physical and chemical characteristics on the compressive fatigue performance of cementitious composites remains unclear. Therefore, this paper systematically investigated the effect of CNT with different contents and sizes, functional groups and coating layers on the compressive fatigue performance of cementitious composites, including fatigue life, strength, deformation behavior and cracking characteristics. The morphology of the fatigue fracture surface of cementitious composites shows that CNT can refine pore structure, bridge nano/micro-cracks and result in the generation of the multi-directional and network-like fatigue micro-cracks as well as the appearance of the fatigue striation around aggregates. Consequently, by increasing the integrity among each phase of cementitious composites, CNT significantly maximizes the compressive fatigue life (in logarithmic form), strength and failure strain of cementitious composites by 160 %, 43.4 % and 20.6 %, respectively, showing great potential for extending the service life of concrete structures.

A Raman Spectroscopic Study of Calcium Silicate Hydrate (CSH) in the Cement Matrix with CNTs and Oxide Additives

The calcium silicate hydrate (CSH) concentration in the cement paste mixed with different types of carbon nanotubes (CNTs) and oxide additives is compared by using Raman spectroscopy. The pristine, hydroxyl and carboxyl functionalized CNTs are used in this work. The oxide additives are zinc oxide (ZnO), gadolinium oxide (Gd2O3), and silicon oxide (SiO2). A laser wavelength of 785 nm was used to collect the Raman spectra. It was observed that the concentration of calcium silicate hydrate (CSH) is unaffected in CNTs-OPC matrices regardless of the type and weight percentage of the CNTs. The oxides, as expected, show significant effects on the concentration of the CSH in the matrices. An increase in the CSH concentration is observed in the ZnO and Gd2O3 matrices with cement. For the SiO2 cement paste matrix, however, the CSH concentration appears to be decreased. This study shows CSH concentration can be controlled by using oxide additives whereas CNTs do not react chemically with the cement composites.

Carbon-based nanocoating for extended lifetime of conventional scale inhibitor squeeze treatment in sandstone reservoirs

Scale inhibition squeeze treatment is a common practice to prevent scale deposition within the downhole utilities, valve applications, and tubular components of the oil and gas producing wells. The conventional squeeze treatment has a short lifetime due to the reservoir rocks' limited adsorption of scale inhibitors and the quick desorption rate. As a result, this process has to be repeated multiple times per year, leading to massive increases in operational costs. Carbon-based nanomaterials are known for their high specific surface area, making them an attractive coating agent to enhance the capability of rocks’ surfaces to adsorb chemicals such as scale inhibitors. In this paper, carbon-based nanomaterials of graphene nanoplatelet (GNPs) and three different types of carbon nanotubes (CNTs) are proposed as novel nanocoating to extend the lifetime of the conventional scale inhibitor squeeze treatment. A natural polymer of Gum Arab (GA) was used to graft the nanomaterials surfaces to ensure a homogeneous and stabilized coating solution. The adsorption of diethylenetriamine penta (methylene phosphonic acid) (DTPMP) scale inhibitor into GNPs and CNTs was investigated using a UV–Vis spectrophotometer. Various characterization techniques such as FTIR, Raman spectroscopy, and XPS were performed to evaluate the interaction between DTPMP and the proposed nanocoating (GNPs/CNTs). Based on UV–Vis results, GNPs was found to be the optimal coating agent with an adsorption capacity of 135 mg/g at ambient temperature and 114 mg/g at 96 °C. Its coating gets saturated with DTPMP within 1 h of interaction. Increasing the initial scale inhibitor concentration was found to increase the adsorption capacity of GNPs. Based on the core flooding conducted on Berea sandstone, the injection of nanocoating into the core sample reduces the permeability by only 12%. Finally, the injected nanomaterial was safely transported through the core, and the primary retention mechanism was adsorption rather than physical filtration/plugging.

Design of smart cementitious composites based on multi-walled carbon nanotubes (MWCNTs) using probe ultrasonicator for dispersion

The purpose of this study is to develop smart cementitious material by incorporating multi-walled carbon nanotubes (MWCNTs). Two different types of carbon nanotubes (CNT) were dispersed using probe ultrasonicator; (i) Pristine CNT (P-CNT), and (ii) Functionalized CNT through annealing (A-CNT). Percolation threshold and optimum content of CNTs were determined by measuring electrical resistivity, porosity, compressive and flexural strengths at various contents of CNTs (0, 0.5 %, 0.75 %, and 1 % with respect to mass of cement). Self-sensing study was also carried out on smart material by relating the electrical properties with cyclic compressive loading. For this purpose, the electrical response was recorded with Wheatstone Bridge (WSB) circuit. The effect of curing and saturation degree of specimens on the resistivity pattern was also discussed. The results of electrical resistivity and mechanical properties showed that the content of CNTs should be at least 0.75 % to develop smart cementitious materials with a significant sensitivity and without detrimental effect on the mechanical properties. Moreover, smart material incorporating pristine CNT provides better sensitivity of self-sensing response as compared to the annealed CNT. Self-sensing test results also showed that with the increase in the content of CNT, sensitivity and repeatability of the sensing response were improved.

Vibration characteristics of piezoelectric functionally graded carbon nanotube-reinforced composite doubly-curved shells

This paper presents an analytical solution for the free vibration behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) doubly curved shallow shells with integrated piezoelectric layers. Here, the linear distribution of electric potential across the thickness of the piezoelectric layer and five different types of carbon nanotube (CNT) distributions through the thickness direction are considered. Based on the four-variable shear deformation refined shell theory, governing equations are obtained by applying Hamilton’s principle. Navier’s solution for the shell panels with the simply supported boundary condition at all four edges is derived. Several numerical examples validate the accuracy of the presented solution. New parametric studies regarding the effects of different material properties, shell geometric parameters, and electrical boundary conditions on the free vibration responses of the hybrid panels are investigated and discussed in detail.