Introduction Of Multi-walled Carbon Nanotubes Research Articles

Shear-stiffening porous material with impact-hardening functionality: Application in hydrogen explosion safety protection

In this study, a shear-stiffening composite porous material (PU@CS) was developed using the dipping-drying technique, with polyurethane (PU) as the substrate. PU@CS not only overcomes the cold flow drawbacks of shear-stiffening gel (SSG) but also significantly enhances the mechanical properties of PU (with a one-order-of-magnitude increase in maximum storage modulus). The introduction of multi-walled carbon nanotubes (MWCNTs) overcomes the electrostatic aggregation drawback of PU. Due to its outstanding shear hardening effect, PU@CS exhibits superior explosion-proof compared to PU, and when filled to a length of 50 cm, it achieves complete quenching of hydrogen gas explosion flames, with a maximum explosion overpressure attenuation ratio of 87.2%. This work provides data support for the application of SSG in the field of explosion protection.

Few-layer V2C/MWCNT with high ionic accessibility for lithium-ion storage.

A V2C MXene has a high theoretical capacity and low diffusion barrier, showing tremendous potential in lithium-ion batteries. However, most reports on V2C focus on a multilayered structure that is stacked, which diminishes the ionic accessibility and results in unsatisfactory cycling stability. Therefore, we synthesized a few-layer V2C (f-V2C) material and added multi-walled carbon nanotubes (MWCNTs). The formed f-V2C/MWCNT provides abundant pores, which enhance ionic accessibility, so that Li+ can easily enter the layer space. The introduction of MWCNTs can further separate the f-V2C, expand the specific surface area, reduce the charge transfer resistance, and heighten the structural stability. The experiments reveal that f-V2C/MWCNT has a high specific capacity of 531 mA h g-1 at 0.1 A g-1 after 100 cycles. Even at a high current density of 5.0 A g-1, the specific capacity can still reach 166 mA h g-1. Moreover, the f-V2C/MWCNT structure shows good cycling stability with a capacity retention rate of 95% after 1000 cycles at 5.0 A g-1. The above findings indicate that f-V2C/MWCNT has great application potential in the field of Li+ storage.

Preparation of wheat flour-derived carbon/multi-walled carbon nanotubes/nickel composite by kneading method for electromagnetic wave absorption

Wheat flour-derived carbon/multi-wall carbon nanotubes/Nickel magnetic particles (WFC/MWCNT/Ni) composite electromagnetic wave (EMW) absorber had been made by traditional kneading technology. Compared to conventional hard template biomass materials, kneading dough can disperse multi-wall carbon nanotubes (MWCNT) and nickel salts more uniformly. The introduction of MWCNT can tune the dielectric constant of Wheat flour-derived carbon (WFC) to achieve stronger dielectric loss. The Ni magnetic particles encapsulated in the carbon matrix not only provide the composite with magnetic loss capability, likewise also improve the impedance match conditions of the material. In addition, the ternary structure of WFC/MWCNT/Ni endows the EMW absorber with more polarization losses. The results show that at a matched thickness of 1.38 mm, the sample achieves minima reflect loss (RLmin) of − 74.03 dB and an effective absorption bandwidth (EABW, RL≤−10 dB) of 4.72 GHz. Benefitting from broadband absorption under relatively thin thickness, simple preparation process and easy availability of raw materials, it possesses enormous potential to become an efficient EMW absorption material.

Magnesium oxychloride cement-based composites for latent heat storage: The effect of the introduction of multi-walled carbon nanotubes

Magnesium oxychloride cement-based composites for latent heat storage: The effect of the introduction of multi-walled carbon nanotubes

An Electrochemical Sensor for Trimethoprim Based on a Magnetic Molecularly Imprinted Carbon Paste Electrode

In order to achieve simple, rapid, and highly sensitive detection of trimethoprim (TMP), a magnetic molecularly imprinted carbon paste electrode (MCPE) was prepared by drop-coating magnetic molecularly imprinted polymer (MIP@Fe3O4@MWNTs) on the surface of reduction graphene oxide (rGO)/MCPE doped with Fe3O4@MWNTs. The introduction of multi-walled carbon nanotubes (MWNTs) and rGO served as dual signal-amplification materials, which can improve the response sensitivity of the sensor. In addition, the magnetic interaction between the substrate electrode and the molecularly imprinted material was beneficial to increasing the stability of the sensor. As expected, the electrochemical sensor not only showed sensitivity and selectivity for the detection of TMP, but it also possessed good stability. The detection range for TMP was 4.0 × 10−9~5.0 × 10−4 mol/L, and the detection limit was 1.2 × 10−9 mol/L. The response performance varied within 10% when the sensor was placed for more than 2 months and used more than 60 times. The spiked recoveries of TMP in environmental water samples, urine samples, and pharmaceuticals (drugs) were between 91% and 110%, and the relative standard deviation (RSD) was within 5%.

Effect of carbon nanotubes incorporation on the properties of the PEO coatings formed on MgMn-Ce alloy

The properties of coatings formed on the MA8 magnesium alloy by the plasma electrolytic oxidation in electrolytes containing multi-walled carbon nanotubes in concentrations of 2, 4 and 6 g/l have been investigated. It was found that the introduction of multi-walled carbon nanotubes leads to an increase in the adhesive strength, microhardness and Young’s modulus of the obtained layers.

A CNT-Toughened Strategy for In-Situ Repair of Aircraft Composite Structures.

This study aimed to develop an in-situ field-repair approach, especially for aircraft composite structures, to enhance the interlaminar toughness of plain-woven composites (PWCs) by adding multi-walled carbon nanotubes (MWCNTs). MWCNTs were dispersed at each interface between prepreg layers by means of solvent spraying, with a density of 1.58 g/m2. Then, the layers were stacked with the predefined sequence and cured at 120 °C and 1 bar pressure, using a heat-repairing instrument. A standard double cantilever beam (DCB) test was used to investigate the interlaminar toughening effect that was due to the MWCNTs. For comparison, original samples were also prepared. The results indicated that the introduction of MWCNTs can favorably enhance the interlaminar toughness of PWCs in a field-repair approach and the Mode I fracture energy release rate, GIC, increased by 102.92%. Based on the finite element method (FEM) of continuum damage mechanics, the original samples and the MWCNTs toughening specimen under DCB Mode I fracture were modeled and analyzed. The simulation and the experiment were in good agreement. Finally, when the toughening mechanism of MWCNTs was explored with a scanning electron microscope (SEM), we found that a large amount of fiber-matrix (F-M) interface debonding and matrix cracking in mountain shape were the major modes of fracture, accompanied by a small amount of fiber breakage and matrix peeling for the MWCNTs-toughening specimens.

Ultrahigh electrochemical performance in mixed-valence Cu1.85Se-based anode for supercapacitors

Mixed-valence is an effective way to achieve high electrochemical performance of anodes for supercapacitor. However, inordinate mixed valence with more structural defects leads to structural instability. The development of mixed valence electrodes that can maintain a stable structure during the defect formation process is the key to resolving this problem. Cu2-xSe with mixed-valence is a potential candidate, the stable monoclinic structure of Cu2Se can be transformed into another stable cubic structure (x > 0.15). Herein, Cu1.85Se anode with mixed valence reveals the ultrahigh specific capacity of 247.8 mA·h/g at 2 A/g. Furthermore, the introduction of multi-walled carbon nanotubes (MWCNTs) into Cu1.85Se further improves the specific capacity (435 mA·h/g at 2 A/g). XRD shows that the introduction of MWCNTs can improve the reversibility via chemical interactions and accelerate the electron transfer in the Cu1.85Se/MWCNTs. Notably, the assembled symmetric supercapacitor (SC) device expresses a high energy density of 41.4 W·h/kg, and the capacity remains 83% even after 8000 charge/discharge cycles. This research demonstrates the great potential of developing high specific capacity anode materials for superior performance supercapacitor.

Triboelectric nanogenerator metamaterials for joint structural vibration mitigation and self-powered structure monitoring

A metamaterial-inspired triboelectric nanogenerator (META-TENG) is proposed in this work to simultaneously realize vibration suppression and energy harvesting. The compact META-TENG can generate low frequency local resonant phenomenon and significantly reduce the incident vibration at the low-frequency band. A planar spring is created, which guarantees low-frequency resonance and a sufficient triboelectric contact surface within a small-scale device. The bandgap property of the proposed metamaterial is then calculated using the finite element method and corresponds well with the experimental measurement results. To fabricate the TENG, fluorinated ethylene propylene (FEP) film and Ecoflex are employed as the negative and positive triboelectric materials, respectively. It is found that the introduction of multi-walled carbon nanotubes (MWCNTs) into Ecoflex is favorable for enhancing the META-TENG’s output performance, increasing the output voltage by almost three times. The charge density of the TENG can reach up to 453.1μC/m2under 5 N sinuous excitation. The periodic META-TENG configuration also exhibits satisfying vibration suppression performance, where the vibration amplitude of an aluminum plate integrating four META-TENGs is minimized by up to 87 %. The harvested energy from the META-TENG array enables an accelerometer and Bluetooth module to work in wireless mode, making the whole system achieve self-powered vibration monitoring.

Synthesis and characterization of Al+0.25%MWCNTs nanocomposite with reduced thermal expansion coefficient

The present work investigates the thermodynamic and structural behaviours of an aluminium-based nanocomposite reinforced by Multi-walled Carbon Nanotubes (MWCNT). Mixture of A999 aluminium powder and MWCNTs was prepared through CVD method in a rotating reactor. 0.25% of MWCNT with average size between 10 nm and 20 nm was chosen to reinforce aluminium-based nanocomposite. Several experimental techniques, such as Calorimetry, X-ray diffraction, Thermogravimetry, Raman spectroscopy, and Dilatometry have been used in this research to explore the thermodynamic and structural behaviours. The DSC curve of Al+0.25%MWCNTs shows a high heat capacity. It is completely different from that of pure aluminium prepared in the same conditions. The thermogravimetric (TG) variation of the nanomaterial is linear compared to that of the matrix (Al). This demonstrates the stability of the material. Raman spectroscopy shows that the insertion of 0.25%MWCNTs generates few defects. X-Ray diffraction (XRD) shows that the peak intensities for Al+0.25%MWCNTs are significantly lower than those of pure aluminium. Relative dimensional variations along the two significant directions (normal to the rolling plane, Z, and within the rolling plane, X) have similar shapes but different intensities. The thermal expansion coefficients are also distinct, expansion along the Z direction is very small; the Al+0.25%MWCNTs thermal expansion is strongly anisotropic. The obtained results show that the introduction of MWCNTs in an aluminium matrix completely changed the behaviour of the studied physical quantities.

Rheological Properties of MWCNT-Doped Titanium-Oxo-Alkoxide Gel Materials for Fiber Drawing.

A strategy of doping by multi-walled carbon nanotubes (MWCNT) to enhance mechanical strength and the electrical conductivity of ceramic fibers has nowadays attracted a great deal of attention for a wide variety of industrial applications. This study focuses on the effect of MWCNTs on rheological properties of metal alkoxide precursors used for the preparation of nanoceramic metal oxide fibers. The rheological behavior of MWCNT-loaded titanium alkoxide sol precursors has been evaluated via an extensional rheometry method. A substantial decrease in elongational viscosity and relaxation time has been observed upon an introduction of MWCNTs even of low concentrations (less than 0.1 wt.%). A high quality MWCNT/nanoceramic TiO2 composite fibers drawn from the specified precursors has been validated. The MWCNT percolation, which is mandatory for electrical conductivity (50 S/m), has been achieved at 1 wt.% MWCNT doping.

Flexible Temperature Sensor Utilizing MWCNT Doped PEG-PU Copolymer Nanocomposites.

In this study, polyethylene glycol (PEG) and polyurethane (PU)-based shape-stabilized copolymer nanocomposites were synthesized and utilized for developing low-cost and flexible temperature sensors. PU was utilized as a flexible structural material for loading a thermosensitive phase change PEG polymer by means of physical mixing and chemical crosslinking. Furthermore, the introduction of multi-walled carbon nanotubes (MWCNT) as a conductive filler in the PEG-PU copolymer resulted in a nanocomposite with thermoresistive properties. MWCNT loading concentrations from 2 wt.% to 10 wt.% were investigated, to attain the optimum conductivity of the nanocomposite. Additionally, the effect of MWCNT loading concentration on the thermosensitive behavior of the nanocomposite was analyzed in the temperature range 25 °C to 50 °C. The thermosensitive properties of the physically mixed and crosslinked polymeric nanocomposites were compared by spin coating the respective nanocomposites on screen printed interdigitated (IDT) electrodes, to fabricate the temperature sensor. The chemically crosslinked MWCNT-PEG-PU polymeric nanocomposite showed an improved thermosensitive behavior in the range 25 °C to 50 °C, compared to the physically mixed nanocomposite. The detailed structural, morphological, thermal, and phase transition properties of the nanocomposites were investigated using XRD, FTIR, and DSC analysis. XRD and FTIR were used to analyze the crystallinity and PEG-PU bonding of the copolymer nanocomposite, respectively; while the dual phase (solid–liquid) transition of PEG was analyzed using DSC. The proposed nanocomposite-based flexible temperature sensor demonstrated excellent sensitivity, reliability and shows promise for a wide range of bio-robotic and healthcare applications.

Early Recognition of the PCL/Fibrous Carbon Nanocomposites Interaction with Osteoblast-like Cells by Raman Spectroscopy.

Poly(ε-caprolactone) (PCL) is a biocompatible resorbable material, but its use is limited due to the fact that it is characterized by the lack of cell adhesion to its surface. Various chemical and physical methods are described in the literature, as well as modifications with various nanoparticles aimed at giving it such surface properties that would positively affect cell adhesion. Nanomaterials, in the form of membranes, were obtained by the introduction of multi-walled carbon nanotubes (MWCNTs and functionalized nanotubes, MWCNTs-f) as well as electro-spun carbon nanofibers (ESCNFs, and functionalized nanofibers, ESCNFs-f) into a PCL matrix. Their properties were compared with that of reference, unmodified PCL membrane. Human osteoblast-like cell line, U-2 OS (expressing green fluorescent protein, GFP) was seeded on the evaluated nanomaterial membranes at relatively low confluency and cultured in the standard cell culture conditions. The attachment and the growth of the cell populations on the polymer and nanocomposite samples were monitored throughout the first week of culture with fluorescence microscopy. Simultaneously, Raman microspectroscopy was also used to track the dependence of U-2 OS cell development on the type of nanomaterial, and it has proven to be the best method for the early detection of nanomaterial/cell interactions. The differentiation of interactions depending on the type of nanoadditive is indicated by the ν(COC) vibration range, which indicates the interaction with PCL membranes with carbon nanotubes, while it is irrelevant for PCL with carbon nanofibers, for which no changes are observed. The vibration range ω(CH2) indicates the interaction for PCL with carbon nanofibers with seeded cells. The crystallinity of the area ν(C=O) increases for PCL/MWCNTs and for PCL/MWCNTs-f, while it decreases for PCL/ESCNFs and for PCL/ESCNFs-f with seeded cells. The crystallinity of the membranes, which is determined by Raman microspectroscopy, allows for the assessment of polymer structure changes and their degradability caused by the secretion of cell products into the ECM and the differentiation of interactions depending on the carbon nanostructure. The obtained nanocomposite membranes are promising bioactive materials.

Self-energized organic-inorganic hybrid composite for surface enhanced Raman spectroscopy

In this study, we integrate plasmonic metal nanomaterials with a piezoelectric polyvinylidene fluoride (PVDF) polymer and lithium niobate (LiNbO3) based composite to form an all-solid-state flexible self-energized sensor. We demonstrate that following the application of a load, the film enhances the surface-enhanced Raman spectroscopy (SERS) signal of an analyte molecule up to 14 times. The piezoelectric β-phase of PVDF in the film is optimized through the introduction of multi-walled carbon nanotubes and post-fabrication UV irradiation annealing. Additionally, the SERS signal enhancement can be further increased by the application of in situ UV light irradiation of the sample, resulting in the generation of photoexcited electrons from LiNbO3 microparticles introduced into the composite. Both the application of a mechanical displacement and the UV light-induced charge generation result in an improved charge transfer between the film and an analyte molecule. The piezoelectric PVDF/LiNbO3 film has been shown to be a suitable SERS platform for the detection of important biological molecules, demonstrating the potential of the substrate for fast on-site detection applications.

Assessing the performance of electrospun nanofabrics as potential interlayer reinforcement materials for fiber-reinforced polymers

Multiscale-reinforced polymers offer enhanced functionality due to the three different scales that are incorporated; microfiber, nanofiber, and nanoparticle. This work aims to investigate the applicability of different polymer-based nanofabrics, fabricated via electrospinning as reinforcement interlayers for multilayer-fiber-reinforced polymer composites. Three different polymers are examined; polyamide 6, polyacrylonitrile, and polyvinylidene fluoride, both plain and doped with multiwalled carbon nanotubes (MWCNTs). The effect of nanotube concentration on the properties of the resulting nanofabrics is also examined. Nine different nanofabric systems are prepared. The stress–strain behavior of the different nanofabric systems, which are eventually used as reinforcement interlayers, is investigated to assess the enhancement of the mechanical properties and to evaluate their potential as interlayer reinforcements. Scanning electron microscopy is employed to visualize the morphology and microstructure of the electrospun nanofabrics. The thermal behavior of the nanofabrics is investigated via differential scanning calorimetry to elucidate the glass and melting point of the nanofabrics, which can be used to identify optimum processing parameters at composite level. Introduction of MWCNTs appears to augment the mechanical response of the polymer nanofabrics. Examination of the mechanical performance of these interlayer reinforcements after heat treatment above the glass transition temperature reveals that morphological and microstructural changes can promote further enhancement of the mechanical response.

Increasing fracture toughness of zirconia-based composites as a synergistic effect of the introducing different inclusions

The effect of multi-walled carbon nanotubes (MWCNTs) and hexagonal boron nitride (h-BN) inclusions on the fracture toughness of yttria-stabilized zirconia (YSZ) ceramics has been studied. It is shown that an increase in the MWCNTs and h-BN content has a positive effect on the K1C of zirconia ceramics. The greatest increase in the fracture toughness of YSZ ceramics was observed with the introduction of hexagonal boron nitride particles. For YSZ ceramics, the K1C value was ≈6.1 MPa m1/2, for ceramics with a 5 wt % of h-BN K1C ≈ 9.2 MPa m1/2. It was shown that an increase of the YSZ ceramics fracture toughness with the introduction of MWCNTs and h-BN, both and separately was provided by the combined action of several mechanisms of increasing the work of crack propagation. In addition, in all composites obtained in this work, the transformation of tetragonal ZrO2 into monoclinic was observed.

ZnO nanoparticles decorated multiwall carbon nanotube assisted ZnMgAl layered triple hydroxide hybrid photocatalyst for visible light-driven organic pollutants removal

Multiwall carbon nanotubes (MWCNTs) supported by zinc-oxide nanoparticles with a ZnMgAl layered-triple-hydroxide (LTH) hybrid was synthesised via direct hydrothermal treatment. In the present investigation, the photocatalytic activity of the prepared hybrid materials was investigated using methylene blue and colourless phenol under visible light irradiation. The photocatalytic degradation efficiency of LTH, MWCNT, and MWCNT ZnO LTH is 48.11%, 4.4%, and 96.7% respectively. The prepared hybrid nanostructure shows a high photocatalytic property due to its synergetic effect, high charge carrier separation, and enhanced visible light absorption surface. The results indicated that the introduction of MWCNTs into the prepared catalyst can increase the photocatalytic activity because the oxidised MWCNTs act as a charge/electron transfer medium in the composite material. The trapping study was performed to examine the role of the active species in the photodegradation process. The abundance of more hydroxyl groups on the surface of the MWCNTs and in the LTH may efficiently improve the photocatalytic activity. The use of MWCNTs improved the catalytic activity of the prepared photocatalyst. The prepared hybrid material especially enhances the visible light absorption and, thus, the photocatalytic activity and cycle stability of the catalyst material.

Effects of multi-walled carbon nanotubes on the state of the nervous system of experimental animals during intratracheal administration in doses corresponding to real production exposures

Introduction. Due to the expansion of production volumes and applications of multi-wall carbon nanotubes (MWCN), a comprehensive toxicological assessment of the nanomaterial is required, followed by the development of approaches to regulating their content in various facilities to reduce the risks of adverse effects on human health. The aim of the study was to assess the state of the nervous system of experimental animals in response to intrapharyngeal introduction of MWCN in doses corresponding to real production exposures. Materials and methods. The object of the study was two-month-old C57BL mice. The experimental groups received by pharyngeal aspiration 20 mcg of MWCN in 0.1% solution of Twin 80; the control group was administered 0.1% Twin 80 in the same way. The nervous system was evaluated 24 hours and 30 days after exposure in a battery of behavioral tests. Results. The use of the "Open field" method allowed us to establish signs of increased anxiety and weakening of research responses in the experimental group 24 hours after exposure. After 30 days, the experimental group showed an increased level of anxiety in variable stress conditions compared to the control group. Conclusions. Thus, the conducted studies revealed some behavioral deviations in the experimental group compared to the control group 24 hours and 30 days after exposure, which suggests the presence of a General systemic or stress reaction to the introduction of the MWCN suspension.

Development of Lightweight and High-Performance Ballistic Helmet Based on Poly(Benzoxazine-co-Urethane) Matrix Reinforced with Aramid Fabric and Multi-Walled Carbon Nanotubes.

This study aims to develop a lightweight ballistic helmet based on nanocomposite with matrix of the copolymer of benzoxazine with an urethane prepolymer [poly(BA-a-co-PU)], at mass ratio 80/20, reinforced with aramid fabric and multi-walled carbon nanotubes (MWCNTs). This has a protection level II according to the National Institute of Justice (NIJ) 0106.01 standard. The effects of MWCNTs mass content in a range of 0 to 2 wt% on tensile, physical and ballistic impact properties of the nanocomposite were investigated. The results revealed that the introduction of MWCNTs enhanced the tensile strength and energy at break of the nanocomposite; the highest values were obtained at 0.25 wt%. In addition, the nanocomposite laminate with 20 plies of aramid fabric showed the lowest back face deformation of 8 mm which was much lower than that specified by the NIJ standard. According to Military Standard (MIL-STD) 662F, the simulation prediction revealed that the ballistic limit of the ballistic helmet nanocomposite was as high as 632 m s−1. The developed laminates made of aramid fabric impregnated with poly(BA-a-co-PU) 80/20 containing 0.25 wt% MWCNTs showed great promise for use as a light weight and high-performance ballistic helmet.

Shape memory microparticles with permanent shape reconfiguration ability and near infrared light responsiveness

Smart changing microparticles with controllable shapes have attracted considerable attentions due to their potential applications in microactuators, micromotors and biomedical devices. In this work, a shape memory microsphere based on cellulose acetate (CA) was developed by a simple emulsion solvent evaporation method to perform on-demand shape switch under heat stimulus. The morphology of CA microparticles before and after thermal programing were carefully investigated by both optical microscope and scanning electron microscope, demonstrating their excellent microscopic shape memory properties and shape reconfiguring ability as needed. The temporary and permanent shapes of CA microparticles both can be changed arbitrarily by regulating the stretching condition via a film stretching process to meet various requests. Considering the more convenience of near infrared (NIR) light than direct heat for application, the additional NIR light-induced microscopic shape memory performance was realized by the introduction of multi-walled carbon nanotube into CA microspheres, which can further improve their versatile application potential in various fields.