Amount Of Multi-walled Carbon Nanotubes Research Articles

Design and development of low‐weight and high‐strength electromagnetic shielding nanocomposite in a microwave frequency range

AbstractIn this novel work, we fabricated the multiwalled carbon nanotubes (MWCNTs)/polypyrrole (PPy) nanocomposite by employing the novel ultrasonic dual mixing (UDM) method. Subsequently, the atomistics and structural characterizations of the fabricated MWCNT/PPy nanocomposite (PM) were performed using SEM, Raman, and XRD. Furthermore, we experimentally evaluated the mechanical properties of the fabricated PM by reinforcing the PPy matrix with MWCNTs at different wt.%. The experimental study of PM shows that the mechanical properties depend upon the amount and dispersion quality of MWCNTs in the PPy matrix. In order to validate the experimental outcomes, the conservative fully coupled finite element (FE) models were developed using the ANSYS Workbench and novel FEAST software. The electromagnetic interference (EMI) shielding effectiveness (SE) of developed PM was also calculated at different thicknesses of PM by taking the effect of SE due to absorption (SEA) and SE reflection (SER) in the microwave frequency range of the C‐band (5.37–8.2 GHz) into consideration. The total SE (SET), the cumulative sum of SEA and SER, is the strong function of the thickness of the PM. Additionally, our study's outcomes reveal that as the thickness of the PM increased, the SET also increased by dominating the SEA rather than the SER. The SET value of 75 dB was observed for a sample with a thickness of 3 mm, indicating a high level of shielding. Thus, material becomes a highly attractive option for achieving high‐performance EMI SE in the C‐band for satellite communications, Wi‐Fi devices, weather radar systems, surveillance, and cordless telephones. A complex permittivity and permeability were also studied using the Nicolson–Ross–Weir (NRW) method to understand the mechanism behind the EMI SE.Highlights Nanocomposite fabricated using the novel ultrasonic dual mixing method. FE models were developed to validate experimental results. The EC and EMI SE are improved with the increase in the sample thickness. Absorption, rather than reflection, dominated the shielding mechanism. SE was observed dB with good mechanical properties.

Structural and morphological studies of g-C3N4-functionalized MWCNTs nanocomposite for sunlight-responsive photocatalytic activity

Photocatalytic degradation of organic contaminants has been proven to be one of the greatest economical and efficient techniques to address environmental pollution problems. Multi-walled carbon nanotubes (MWCNTs)/g-C3N4 (GCN) nanocomposites (NCs) were synthesized by a hydrothermal process aided by ultrasound to produce active photocatalysts. The effective synthesis of GCN, MWCNTs, and MWCNTs/GCN NCs was confirmed by X-ray diffraction (XRD) patterns. The fabrication of GCN nanosheets (NSs), the nanotubular structure of MWCNTs, and a network of neuron-like structures for MWCNTs/GCN NCs were all revealed by structural and morphological characterization. The elemental mapping of NCs containing the suitable quantity of MWCNTs revealed a uniform distribution of the sample's component elements. When the optical properties of the fabricated nanomaterials were examined by employing UV–visible spectroscopy, the results revealed a blue shift (a shift of maximum absorption to the UV region), which suggests that the addition of MWCNTs increased the band-gap energy. The behaviour of e––h+ pair recombination was revealed by measuring the charge carrier movement and trapping efficiency using photoluminescence (PL) spectroscopy. Crystal violet (CV) dye was photocatalytically degraded using prepared NCs in the presence of sunlight, and the synergistic effects of GCN and MWCNTs were examined. With a degradation efficiency of 99.32 %, MWCNTs/GCN NCs demonstrated the best sunlight-irradiated photocatalytic activity for CV degradation. The degradation of CV was discovered to follow pseudo-first-order kinetics. Throughout five consecutive studies, the NCs demonstrated the highest levels of catalytic efficiency and recyclability, with 5 % reduced degrading activities. The trapping tests showed that the primary reactive species involved in the breakdown of CV were the •O2– and •OH radicals.

Bacterial cellulose-based Janus energy storage phase change composite aerogel for efficient interfacial solar vapor generation

Interfacial solar evaporation systems based on Janus structures exhibit potential application prospects in terms of salt tolerance. However, intermittent and unstable light conditions limited the evaporation rate and water production performance of the evaporators. The introduction of energy storage phase change (ESPC) composite materials into the interface solar evaporators can effectively solve this problem. In this work, bacterial cellulose (BC) is selected as the matrix material, sodium alginate (SA) and multi-walled carbon nanotubes (MWCNTs) are added as functional fillers, and porous composite aerogels are prepared using direct freeze-drying. On this basis, Janus porous composite aerogel (J-BCS/CNT) with ESPC function is further constructed by depositing paraffin onto the upper layer of the aerogel through a unilateral vacuum impregnation method. The aerogel exhibits strong photothermal conversion capabilities and excellent thermal management properties. The addition of appropriate amount of MWCNTs enables it to obtain high latent heat storage and release functions, providing energy for operation in dark conditions. Under the solar irradiation of 1.5 kW m−2, J-BCS/CNT40% aerogel exhibits a high evaporation rate of 1.95 kg m−2h−1 in pure water and 0.67 kg m−2h−1 under dark conditions. The salt evaporation resistance test shows that the aerogel has excellent purification capabilities in high-concentration salt water (20 wt%) solutions. More importantly, the long-term energy storage-release tests of J-BCS/CNT in 3.5 wt% saline water indicate that the aerogel reveals excellent sustainability and latent heat release functions.

Influence of the Dispersion of Carbon Nanotubes on the Electrical Conductivity, Adhesion Strength, and Corrosion Resistance of Waterborne Polyurethane Composites

Due to the presence of many flammable substances in the working environments of the petrochemical industry, anticorrosive conductive coatings need to be used on metal equipment to avoid safety accidents like fires. However, existing conductive solvent-based coatings are volatile when exposed to flammable and toxic organic solvents. Thus, in this work, a series of eco-friendly anticorrosive waterborne polyurethane (WPU) composites with multi-walled carbon nanotubes (MWCNTs) were prepared via a low-cost and practical process; the dispersion of MWCNTs was revealed when present in different amounts, and the mechanism behind the conduction of WPU composites was determined. We concluded that low amounts of MWCNTs were well dispersed, generating a conductive network, and the WPU composite was not entirely covered by the MWCNT particles, so the electrical conductivity in certain parts of the coating was good. When the content of MWCNTs was excessive, some stretched MWCNTs dispersed to the top of the composite and many MWCNTs agglomerated at the bottom. Additionally, when the content of MWCNTs was increased, the electrical conductivity, corrosion resistance, and adhesion strength of the WPU composite decreased. Our results could provide a theoretical foundation for the preparation of anticorrosive conductive waterborne composites for protecting equipment in the petrochemical industry.

Reconfigurable light-responsive liquid crystal elastomer /carbon nanotube nanocomposite actuators operated by photothermal effects and dynamic exchange reaction

Monodomain liquid crystal elastomers (MLCEs), exhibiting a light-induced dynamic exchange reaction (DER) and light-triggered actuation abilities, were prepared using dispersed multiwalled carbon nanotubes (MWCNTs) and allyl sulfide linkages incorporated in the MLCE matrix. MWCNTs were dispersed in the MLCE matrix using a newly synthesized dispersant, poly(4-cyanobiphenyl-4′-oxyundecylacrylate-co-pyrene methyl acrylate); this dispersant exhibited amphiphilic properties of π–π interactions with the MWCNT fillers (attributed to the pyrene moieties) and miscibility with the MLCE matrix (attributed to the cyanobiphenyl mesogenic moieties). A low amount of well-dispersed MWCNTs (≤0.05 wt%) in the MLCE matrix induced excellent photothermal effects under near-infrared (NIR) light irradiation, leading to considerable reversible contraction/extension actuation (∼40 % change in length). The bilayer film comprising the MLCE and PLCE (PLCE: polydomain LCE) composite films bonded via DER without glue exhibited excellent bending actuation under NIR light irradiation and was configured into several actuators such as a flower-shaped actuator, a weightlifter, a circular rolling band, an oscillator mimicking a hummingbird, and a casting catapult. Therefore, this novel MLCE/CNT composite film enhances the design ability for the arbitrary shaping and functionalization of NIR light-triggerable LCE actuators, which can be applied to several interesting soft robots.

Exploring the optical and electric features of PMMA/PVAc blended polymers doped with TBAI/MWCNTs fillers for different applications

The present study focuses on the production of poly (methyl methacrylate)/poly (vinyl acetate)/tetrabutylammonium iodide/multi-walled carbon nanotubes (PMMA/PVAc/TBAI/x wt %MWCNTs) blended polymers. These blends show great potential for use in advanced optical, energy storage and electronics applications. X-ray diffraction (XRD) and scanning electron microscopy techniques was used to explore the structure and morphology of PMMA/PVAc/TBAI with x wt% MWCNTs blended polymers. The optical transmittance lowered to a minimum value of 53–63 % within the specific wavelength range as the blend contained 0.55 wt % multi-walled carbon nanotubes (MWCNTs). The sample containing 0.11 wt% MWCNTs demonstrated the highest reflectance (R) values, whereas the sample with 0.55 wt% MWCNTs showed the lowest R values. As the concentration of MWCNTs increased, these values consistently decreased. The smallest direct (4.55 eV) and indirect (4.45 eV and 2.48 eV) optical band gap (Eg) values were achieved when wt% of MWCNTs were 0.44 % and 0.55 %, respectively. The doped blend with wt% of 0.11 exhibited the highest refractive index values. Blend with x = 0.55 wt % MWCNTs has the highest dielectric constant. The energy density (U) increased non-uniformly as the blend was infused with MWCNTs. Elevating the temperature enhances the values of U for all blends. All blends adhered to the correlated barrier hopping (CBH) model. The effects of MWCNTs doping amount and temperature on the impedance and electric modulus of the host blend were investigated. The dc conductivity of the doped samples was observed to be greater than that of the undoped blend, except for the blend with x = 0.44, where it diminished. The undoped blend displayed activation energy (Ea) values of 1.71 eV and 0.6 eV, depending on the temperature range. When the host blend is doped with MWCNTs, the Ea values either rise or fall depending on the quantity of MWCNTs. All samples have non-ohmic characteristics.

Exploring the optical and electrical features of PVA/CMC/PPy/MWCNTs blended polymers

The objective of this study is to create nanocomposite films using polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), polypyrrole (PPy) and Multi-walled carbon nanotubes (MWCNTs). These nanocomposites show potential for use in a range of optoelectronics devices. The structure and morphology of PVA/CMC/PPy/x wt % MWCNTs blends were explored using X-ray diffraction and scanning electron microscope techniques. In the visible range, the transmittance lowered from 78 to 87 % (PVA/CMC/PPy blend) to 3–5 % (x = 0.25 wt % MWCNTs). The transmittance in the UV range decreased significantly, approaching zero, for the blend containing 0.25 wt % MWCNTs. The material improves the absorption of UV–visible light and efficiently prevents the penetration of UV–visible light. When the concentration of MWCNTs reached 0.05 in the doped blend, the reflectance value improved considerably. The addition of MWCNTs to the PVA/CMC/PPy composite leads to a reduction in the optical bandgap values. The lowest direct and indirect band gaps are (4.98, 4.36) eV and (4.52, 3.19, 2.68, 1.18) eV, respectively, accomplished when the MWCNTs content was 0.2 wt %. A blend containing 0.15 wt % MWCNTs resulted in the highest values of refractive index and nonlinear optical parameters. In the visible light spectrum, the blend with 0.25 wt% MWCNTs had the best optical conductivity values. Doped blends can be used in optoelectronic or photocatalytic applications depended on the amount of MWCNTs doped. The current-voltage characteristics and logarithm of the current density and square root of the electric field strength of PVA/CMC/PPy/x wt % MWCNTs blended polymers at various temperatures were investigated.

Robust and resilient piezoresistive sensor made of MWCNT-embedded aerogel prepared with elongated amyloid fibrils of α-synuclein

Pressure sensors are widely employed in various fields from biomedical to aerospace engineering. Each field requires pressure sensors with specific sensitivity, response time, recovery time, durability, and detection limit. However, developing pressure sensors that meet the increasing demands of high mechanical strength and sensitive electrical responsiveness influencing reliability and accuracy still remains challenging. Herein, a highly robust and resilient piezoresistive sensor was developed by combining elongated amyloid fibrils (eAFs) aerogel made of a self-assembly protein of α-synuclein, which provided stable porous 3D interconnected network and thus increased surface area, and multi-walled carbon nanotube (MWCNT) as a reinforcement material for improved mechanical and electrical properties. Owing to the integration between eAFs aerogel and MWCNT, the MWCNT-embedded eAFs aerogel exhibited augmentation in mechanical strength and resiliency depending on the amount of MWCNT introduced. Additionally, the MWCNT-embedded eAFs aerogel showed piezoresistive properties with stable pressure sensing capability toward human motions, airflow, and underwater pressure. It is, therefore, suggested that the pressure sensor fabricated with the eAFs aerogel containing MWCNT could be utilized in diverse areas including wearable device and artificial skin development.

Eco-friendly fabrication of novel hydrophobic CMC–C18@MWCNTs nano-sorbent for fat content removal in the analysis of polycyclic aromatic hydrocarbons in fatty-food samples

In this study, carbon nanohybrids was developed by hybridizing carboxymethyl cellulose (CMC) biopolymer with various amounts of multi-walled carbon nanotubes (MWCNTs: 0.2, 0.5, 1, 3, and 5%) in eco-friendly process to produce hydrophobic CMC–C18@MWCNTs, which was then used as a sorbent material for fat content in fatty food samples analysis. The hydrophobic biopolymers were synthesized using an ultrasound-assisted esterification process, and the physicochemical properties were analyzed using FT-IR, XRD, TGA, FE-SEM, and TEM. The performance of the hydrophobic nanocomposites was evaluated by assessing their ability to remove fat content during polycyclic aromatic hydrocarbon (PAHs) analysis in tuna samples. The results showed that CMC–C18–CNT0.2% provided the best peak shapes and highest recoveries for PAHs compounds, ranging between 74.3 and 89.7%, while CMC–C18–CNT5% had the lowest recoveries, ranging between 0 and 35%. Therefore, the lowest amount of MWCNTs was found to be the most efficient for removing fat content with providing high PAHs recovery, while increasing the MWCNTs percentage increased the hydrophobicity and removed PAHs analytes along with fat content. After the investigation, the method was validated using CMC–C18–CNT0.2% in three various levels: 2, 5 and 10 μg kg−1. The obtained results were satisfactory; the average recoveries for all PAHs compounds ranged between 74.3 to 89.7%, and the intra-day precision were estimated by coefficient of variation (%CV), where were less than 10% for all PAHs. The LOD and LOQ were lies between 0.33 to 0.89 μg kg−1 and 1.12 to 1.92 μg kg−1 respectively. For the calibration curve linearity, the correlation coefficient (r2) were higher than 0.999 for all PAHs. Overall, the hydrophobic CMC–C18@MWCNTs are a promising, modifiable, and useful material for fatty food analysis.

Optical and Dielectric Features of PVA/CMC/PVP/ZnMn2O4/CuCo2O4/x wt% MWCNTs Blended Polymers for Optoelectronic Applications

This study is devoted to optimizing the optical and dielectric parameters of polyvinyl alcohol (PVA)/ carboxymethyl cellulose (CMC)/ polyvinylpyrrolidone (PVP) blended polymer by adding ZnMn2O4/CuCo2O4 nanocomposite and controlling the amounts of multi-walled carbon nanotubes (MWCNTs) to engage them in flexible optoelectronics and storage energy capacitors. Herein, 0.9ZnMn2O4/0.1CuCo2O4 was synthesized by co-precipitation and hydrothermal methods and loaded with different ratios of MWCNTs into PVA/CMC/PVP blend to produce films by solution casting procedure. The crystallite size of 0.9ZnMn2O4/0.1CuCo2O4 was determined using transmission electron microscopy. The structures of the filler and doped blends were explored via the X-ray diffraction technique. The optical features of undoped and doped blends were explored by diffused reflectance and fluorescence spectrophotometers. The addition of ZnMn2O4/CuCo2O4 to PVA/CMC/PVP caused a decline of direct and indirect optical band gaps from 5.33 and 5.03 eV to 5.19 and 4.66 eV, respectively. By adding different amounts of MWCNTs, the direct/indirect optical band gap reduced irregularly, and they attained their minimum values (5.07, 4.46) eV as it doped with 0.6 Wt% MWCNTs. The highest values of refractive index, extinction coefficient, optical conductivity and nonlinear optical parameters were achieved in the blend containing ZnMn2O4/CuCo2O4/0.6 Wt% MWCNTs. It is also found that the dielectric constant and ac conductivity rose with the insertion of ZnMn2O4/CuCo2O4/0.6 Wt% MWCNTs. The highest energy density value was found in the polymer blend of PVA/CMC/PVP/ZnMn2O4/CuCo2O4/0.8 Wt% MWCNTs blended polymer. Electrical modulus and Nyquist plots for different blends were also examined. The results recommend the doped blends as a good candidate for optoelectronics and energy storage capacitor applications.

Effect of multi-walled carbon nanotubes reinforcement on self-healing performance of natural rubber

Abstract This work is motivated by the desire to restore the quality of rubber-based product properties with the intention of prolonging the service life period, thus helping create a sustainable environment by proposing effective rubber waste management. This study experimentally investigated an intrinsically self-healing zinc thiolate grafted natural rubber (NRZT) compound filled with multi-walled carbon nanotubes (MWCNT) to assess its influence on mechanical properties and self-healing performance. The MWCNT loading varied to 0, 2, 4, 6, and 8 phr. The Equilibrium swelling test was used to quantify the amount of ionic and covalent crosslinks formed. Fourier Transform Infrared (FTIR) spectra were used to detect the presence of MWCNT in the compound. The mechanical properties computed by the tensile and tear strength tests showed that the incorporation of MWCNT increased both properties up to three and twofold, respectively. However, as expected, the elongation at break (Eb) value was reduced. The unfilled sample showed that it can heal up to ∼98 %, measured from the tensile strength. However, the healing efficiency obtained from tensile strength reduces to ∼88 % by incorporating 2 phr MWCNT. The Eb and its self-healing efficiency gradually decreased as the MWCNT amount increased. All samples showed outstanding properties under the tearing mode, where the healed samples produced higher tear strength (>100 % healing) than the initial value. Scanning Electron Microscopy (SEM) micrographs revealed a noticeable gap along the healed cut line with increased MWCNT numbers, possibly due to the lower reaction between polymerized zinc thiolate (PZTh) radicals with zinc thiolate (ZT) and rubber molecules. The work aims to investigate the influence of MWCNTs on the mechanical and healing performance of self-healing NR composites by comparing them to their unfilled sample.

In situ polymerised polyaniline films over multi-walled carbon nanotubes coatings for enhanced photoelectrochemical performance

Polyaniline (PANI), which is a π-conjugated polymer, has stood out as a promising candidate for dihydrogen generation in photoelectrochemical (PEC) cells owing to its suitable optoelectronic properties and excellent stability. Nevertheless, the PEC performance of this material is still far from adequate for technological applications. Herein, we have focused on improving the PEC performance of PANI films by combining this polymer with multi-walled carbon nanotubes (MWCNTs) layers. Specifically, we have assessed the PEC activity of the in situ polymerised PANI films onto FTO substrates coated with different amounts of MWCTNs for the hydrogen evolution reaction (HER). The FTO/MWCNTs/PANI films with the optimum deposited amount of MWCNTs (i.e., 30 μL) featured a 2.4-fold increase of the cathodic photocurrent density response for the HER compared to that of FTO/PANI film. Moreover, the FTO/(30 μL)-MWCNTs/PANI films exhibited good PEC stability, as observed by the relatively low cathodic photocurrent density decay of up to 7% during 3720 s of stability test. Based on joint analyses of physical and PEC characterisation, the improved PEC performance for the FTO/(30 μL)-MWCNTs/PANI films were assigned to the combined contribution of the following factors: (i) enhancement of light absorption; (ii) possible improvement of excitons dissociation; (iii) minimisation of the electron-hole recombination process; and (iv) facilitation of electrons transfer at the PANI|electrolyte interface for the HER. The enhancement of PEC performance achieved in this work for the fully organic photocathode composed of MWCNTs/PANI paves the way to invest in additional modifications seeking to further improve the dissociation of excitons and the interfacial transfer of charge carriers for the light-driven HER.

Simple surface modification of barium sulfate for improving the interface of polymer composites and its x‐ray shielding properties

AbstractRadiation shielding materials have been researched using Pb and metal oxide particles, and composites of resin and barium sulfate (BaSO4) have been reported. In addition, multiwalled carbon nanotubes (MWCNTs) have often been used as a nanomaterial to improve the mechanical strength of resin–BaSO4 composites. The literature includes no examples of these two materials—BaSO4 and MWCNTs—being used at the interface of composites. We effectively modified the surface of BaSO4 by a simple process involving strong electrostatic interaction between positively charged barium and negatively charged functional groups on the MWCNT surface. The process is simple and can form large amounts of MWCNTs that coat BaSO4 surfaces. As a result, MWCNTs remained on the BaSO4 surface even after the MWCNT‐coated BaSO4 was washed with a solvent and subjected to melt mixing. The physical anchoring of MWCNTs onto the BaSO4 surface improved the interfacial adhesion and mechanical properties of the resultant composites. The originality of this research is that MWCNTs can be coated onto the surface by only electrostatic interaction without using a polymer adhesive. In addition, the x‐ray shielding performance of the MWCNT‐containing composites was the same as that of composites prepared without the MWCNTs.Highlights MWCNTs were coated onto the surface of BaSO4 by electrostatic interaction. Interfacial adhesion of PS composites was improved by coating MWCNTs. The MWCNTs did not affect the x‐ray shielding performance.

Tube-on-rod structure of MWCNTs-ammonium cobalt vanadium oxide/ammonium vanadium oxide; evaluation of electrochemical hydrogen storage capacity

Carbon nanostructures have lately been widely used in energy storage systems. This study examines the impact of ammonium cobalt vanadium oxide/ammonium vanadium oxide as electrode materials in hydrogen storage which modifying with carbon nanostructures. The poor conductivity of vanadate-based materials may be improved by adding zero to two-dimensional carbon nanomaterials, such as graphene quantum dots (GQDs), graphene oxide (GO), and multiwall carbon nanotubes (MWCNTs). Electrode materials based on (NH4)2V12O27·xH2O/(NH4)2Co2V10O28·16H2O/NH4V3O8 were synthesized by hydrothermal method in the presence of PEG with engineered morphology of one dimensional (ID) nanorods. The carbonous nanocomposites based on GQDs, MWCNTs and GO exhibit a capacity 203, 438 and 28 mAhg−1 after 15 cycles at a current density of 1 mA. The hydrogen storage performance is influenced by various amount of MWCNTs. Increasing the percentage of MWCNTs led to decreasing the capacity. Therefore, optimum electrode materials fabricated in the presence of 5 % MWCNTs which has 1055 mAhg−1 capacity. Therefore, 1D/1D structure of Tube-on-Rod can improve the performance of hydrogen storage in the ammonium cobalt vanadium oxide/ammonium vanadium oxide electrodes.

Characterization of airborne dust emissions from three types of crushed multi-walled carbon nanotube-enhanced concretes

Dispersing Multi-Walled Carbon Nanotubes (MWCNTs) into concrete at low (<1 wt% in cement) concentrations may improve concrete performance and properties and provide enhanced functionalities. When MWCNT-enhanced concrete is fragmented during remodelling or demolition, the stiff, fibrous and carcinogenic MWCNTs will, however, also be part of the respirable particulate matter released in the process. Consequently, systematic aerosolizing of crushed MWCNT-enhanced concretes in a controlled environment and measuring the properties of this aerosol can give valuable insights into the characteristics of the emissions such as concentrations, size range and morphology. These properties impact to which extent the emissions can be inhaled as well as where they are expected to deposit in the lung, which is critical to assess whether these materials might constitute a future health risk for construction and demolition workers. In this work, the impact from MWCNTs on aerosol characteristics was assessed for samples of three concrete types with various amounts of MWCNT, using a novel methodology based on the continuous drop method. MWCNT-enhanced concretes were crushed, aerosolized and the emitted particles were characterized with online and offline techniques. For light-weight porous concrete, the addition of MWCNT significantly reduced the respirable mass fraction (RESP) and particle number concentrations (PNC) across all size ranges (7 nm – 20 μm), indicating that MWCNTs dampened the fragmentation process by possibly reinforcing the microstructure of brittle concrete. For normal concrete, the opposite could be seen, where MWCNTs resulted in drastic increases in RESP and PNC, suggesting that the MWCNTs may be acting as defects in the concrete matrix, thus enhancing the fragmentation process. For the high strength concrete, the fragmentation decreased at the lowest MWCNT concentration, but increased again for the highest MWCNT concentration. All tested concrete types emitted <100 nm particles, regardless of CNT content. SEM imaging displayed CNTs protruding from concrete fragments, but no free fibres were detected.

Formation of MWCNT/LiCo2O4 nanoplates and their application for hybrid supercapacitor

In this work, LiCo2O4 nanoplates are prepared by simplest and most adoptable co-precipitation method. The prepared nanomaterial is figured out by several characteristic techniques. Thereafter, LiCo2O4 nanoplates are used for supercapacitor and specific capacitance of 951 F g−1 is observed at 1 A g−1. Further, capacitive performance of LiCo2O4 nanoplates is enhanced by adding up the appropriate amount of multi-walled carbon nanotubes (MWCNTs) and high specific capacitance of 1373 F g−1 is observed at 1 A g−1. Owing to the good specific capacitance of MWCNT/LiCo2O4, hybrid supercapacitor is designed where MWCNT/LiCo2O4 and activated carbon (AC) are utilized as positive (+ve) and negative (-ve) electrodes, correspondingly. Furthermore, the electrochemical performance of MWCNT/LiCo2O4//AC is investigated. The high energy density of 54.84 W h kg−1 at 775 W kg−1 is received from MWCNT/LiCo2O4//AC hybrid supercapacitor. Additionally, two red color light emitted diodes (LEDs), toy motor fan and kitchen timer are functionalized by two MWCNT/LiCo2O4//AC hybrid supercapacitors connected in series.

Study on the Properties of Multi-Walled Carbon Nanotubes (MWCNTs)/Polypropylene Fiber (PP Fiber) Cement-Based Materials.

In order to improve the mechanical properties and durability of cement-based materials, a certain amount of multi-walled carbon nanotubes (MWCNTs) and polypropylene fiber (PP fiber) were incorporated into cement-based materials. The mechanical properties of the multi-walled carbon nanotubes/polypropylene fiber cement-based materials were evaluated using flexural strength tests, compressive strength tests, and splitting tensile tests. The effects of multi-walled carbon nanotubes and polypropylene fiber on the durability of cement-based materials were studied using drying shrinkage tests and freeze-thaw cycle tests. The effects of the multi-walled carbon nanotubes and polypropylene fibers on the microstructure and pore structure of the cement-based materials were compared and analyzed using scanning electron microscopy and mercury intrusion tests. The results showed that the mechanical properties and durability of cement-based materials can be significantly improved when the content of multi-walled carbon nanotubes is 0.1-0.15%. The compressive strength can be increased by 9.5% and the mass loss rate is reduced by 27.9%. Polypropylene fiber has little effect on the compressive strength of the cement-based materials, but it significantly enhances the toughness of the cement-based materials. When its content is 0.2-0.3%, it has the best effect on improving the mechanical properties and durability of the cement-based materials. The flexural strength is increased by 19.1%, and the dry shrinkage rate and water loss rate are reduced by 14.3% and 16.1%, respectively. The three-dimensional network structure formed by the polypropylene fiber in the composite material plays a role in toughening and cracking resistance, but it has a certain negative impact on the pore structure of the composite material. The incorporation of multi-walled carbon nanotubes can improve the bonding performance of the polypropylene fiber and cement matrix, make up for the internal defects caused by the polypropylene fiber, and reduce the number of harmful holes and multiple harmful holes so that the cement-based composite material not only has a significant increase in toughness but also has a denser internal structure.

Evaluating the Potential of Multi-Walled Carbon Nanotube-Modified Clay as a Landfill Liner Material.

In this paper, the feasibility of multi-walled carbon nanotube (MWCNT)-modified clay as a landfill liner material is investigated. Experiments were conducted on the modified clay with 0.5%, 1%, and 2% MWCNTs. The effects of the MWCNTs on the compaction characteristics, permeability coefficient, stress-strain curve, peak deviation stress, shear strength parameters (internal friction angle and cohesion), microstructures, and adsorption performance of the clay were analyzed. The results showed that the optimum moisture content (OMC) increased from 16.15% to 18.89%, and the maximum dry density (MDD) decreased from 1.79 g/cm3 to 1.72 g/cm3 with the increase in MWCNTs. The permeability coefficients firstly fell and then gradually rose as the MWCNTs increased; the minimum permeability coefficient was 8.62 × 10-9 cm/s. The MWCNTs can also effectively increase the peak deviation stress of the clay, and at the maximum level, the peak deviation stress was increased by 286%. SEM images were processed using the Pore and Crack Analysis System (PCAS), and the results showed that the appropriate amount of MWCNTs could fill the pores and strengthen the clay structure. The effect of the MWCNT-modified clay on the adsorption performance of common heavy metal ions Cd2+, Mn2+ and Cu2+ in landfill leachate was analyzed by batch adsorption tests. The maximum adsorption capacities (Qmax) of Cu2+, Cd2+ and Mn2+ in the 2% MWCNT-modified clay were, respectively, 41.67 mg/g, 18.69 mg/g, and 4.97 mg/g. Compared with the clay samples without MWCNTs, the adsorption properties of Cu2+, Cd2+, and Mn2+ were increased by 228%, 124%, and 202%, respectively. Overall, the results suggest that MWCNT-modified clays have the potential to be suitable barrier materials for the construction of landfills.

Effects of multi‐walled carbon nanotubes on structures and properties of heat‐resistant poly(m‐phenylene isophthalamide)‐based hollow fiber ultrafiltration membranes

AbstractThis study is the first attempt to fabricate a heat‐resistant hollow fiber ultrafiltration membrane using poly(m‐phenylene isophthalamide) (PMIA) polymer material, which has rarely been used as conventional polymeric membrane materials. Multi‐walled carbon nanotubes (MWCNTs) are incorporated as reinforcing agents. The PMIA polymer synthesized for this study exhibited an inherent viscosity of 1.6 dL/g, confirming its suitability for membrane fabrication, and successful synthesis was verified through Fourier‐transform infrared analysis. To enhance the dispersibility of MWCNTs during dope solution preparation and their interaction with the PMIA matrix, MWCNTs were acid‐treated and surface characteristics of the acid‐treated MWCNTs were confirmed through x‐ray photoelectron spectroscopy analysis. Scanning electron microscope analysis revealed that the introduction of MWCNTs resulted in thicker PMIA hollow fiber ultrafiltration membranes with symmetrical finger‐like and sponge‐like pore structures. Interestingly, unlike the typical polymer composite systems containing MWCNTs, which often show a dependence on MWCNT content, the mechanical properties of the PMIA/MWCNT membranes in this study seem to exhibit high variability and are not contingent on the MWCNT content. Additionally, filtration performance studies demonstrated that the introduction of MWCNTs substantially increased water permeability, particularly at 1.0 wt% MWCNT content, resulting in a remarkable 130% enhancement compared to pristine PMIA membrane. Simultaneously, even with a small quantity of MWCNTs, the rejection performance of the PMIA/MWCNT membrane witnessed significant improvement due to the reduction in average pore size, effectively overcoming the commonly observed trade‐off phenomenon. In summary, this study clearly showed the effects and changes on the structure and properties of a heat‐resistant PMIA‐based hollow fiber ultrafiltration membranes due to the introduction of MWCNTs.Highlights Heat‐resistant poly(m‐phenylene isophthalamide)‐based hollow fiber ultrafiltration membranes Introduction of multi‐walled carbon nanotubes (MWCNTs) into PMIA membrane as a reinforcing agent Unique structural changes of PMIA membrane originated from the MWCNTs Enhanced tensile strength of PMIA/MWCNT membranes Simultaneous improvement of filtration performance due to MWCNTs

Electrically conductive bamboo charcoal@cellulose nanofibrils based composite membranes designed for electromagnetic interference shielding and flame retardant

Recently, developing multifunctional biochar based materials has been concerned by experts and scholars, but the weak electrical conductivity of biochar itself will limit its application. Targeting this issue, electrically conductive bamboo charcoal (EBC) was constructed for catalytic carbonization by mixing ferric chloride with bamboo charcoal, followed by mixing cellulose nanofibrils (CNF) as the skeleton and a small amount of multi-walled carbon nanotubes (MWCNT) as the conductive enhancer to constract a conductive EBC@CNF@MWCNT composite aerogel by freeze drying. Subsequently, the aerogel was soaked with polydimethylsiloxane (PDMS) and hot pressed into a membrane. In the system, EBC and MWCNT were distributed uniformly in the CNF skeleton to form three-dimensional conducting network, the obtained conductive E @ CNF@M@PDMS composite membrane displayed excellent conductivity (47 S/m) and remarkable EMI shielding performance (39.5 dB, absorption loss of about 75%), as well as good flame retardant ability (LOI of 27.6%) and hydrophobicity (115.4°). Based on its outstanding properties and simple preparation, it is considered to provide a new strategy for developement of environmentally friendly multifunctional biochar based materials.