Behavior Of Multi-walled Carbon Nanotubes Research Articles

Voltametric detection of methylene blue dye in water at green and chemically synthesized Ag/MWCNT modified electrode

Abstract A well-known textile dye, methylene blue (MB) was electrochemically detected by using glassy carbon electrode (GCE), modified with green and chemically synthesized silver nanoparticles (AgNPs) decorating the surface of functionalized multiwalled carbon nanotubes (fMWCNT). The green and chemical methods were used to synthesize AgNPs, which decorated MWCNT forming MWCNT/Agchm and MWCNT/Aggrn nanocomposite. Comprehensive characterization of the nanomaterials was carried out using energy-dispersive x-ray spectroscopy (EDX) detector-equipped scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV), and x-ray diffraction (XRD). Using XRD, particle sizes were found to be 26.81, 10.05, 5.36, 19.26, and 17.48 nm for Agchm, Aggrn, MWCNT, Agchm/MWCNT, and Aggrn/MWCNT, respectively. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV) were employed for the investigation of the electrochemical properties and behaviour of MWCNT, Agchm, Aggrn, Agchm/MWCNT, and Aggrn/MWCNT electrodes, and higher electron transport capabilities and improved electrochemical activity towards MB on Agchm/MWCNT electrode were demonstrated by the results. Electroanalysis of methylene blue at the modified electrodes with square wave technique SWV was successful. At Agchm/MWCNT modified electrode, a low limit of detection (LOD) of 4.684 and limit of quantification (LOQ) of 14.194 pM, for MB, while at Aggrn/MWCNT modified electrode , an LOD and LOQ of 2.935 and 8.895 pM, were recorded respectively. In real sample analysis, the recovery percentage for Agchm/MWCNT ranged from 90 to 98% (n =3), and Aggrn/MWCNT showed a recovery percentage ranging from 97 to 103% (n = 3). Both electrodes’ remarkable recovery rate attest to their dependability and sensitivity in MB detection.

Excellent field emission with enhanced photodetection behavior of multiwalled carbon nanotubes: experimental and theoretical study

In this study, we synthesized multiwalled carbon nanotubes (MWCNTs) using the direct liquid injection chemical vapor deposition (DLICVD) method, the growth temperatures were varied to investigate their unique properties.

Obtaining an accurate prediction model for viscosity of a new nano-lubricant containing multi-walled carbon nanotube-titanium dioxide nanoparticles with oil SAE50

This study aims to investigate the viscosity behavior of multi-walled carbon nanotube (MWCNT) - titanium dioxide (TiO2) (40−60) - SAE50 oil nanofluid using an Artificial Neural Network (ANN) modeling approach. The main objective is to develop a highly accurate predictive model for viscosity by considering three input parameters: temperature, solid volume fraction (SVF), and shear rate (SR). Rheological measurements provide experimental data used to train and validate the ANN model. The ANN model's architecture, activation functions, and training algorithms are carefully chosen. Data are divided to three subsets including train, validation and test. ANN is trained using trainlm algorithm for 50 times to vanish the effect of random nature of ANN weight initialization. The trained ANN model is then utilized to predict the viscosity of the nanofluid under varying conditions. The results demonstrate the efficacy of the proposed ANN model in capturing the complex relationship between viscosity and the input parameters, providing accurate viscosity predictions for the MWCNT-TiO2-oil SAE50 nanofluid. Furthermore, the influence of temperature, SVF, and SR on viscosity is analyzed, offering valuable insights into the flow behavior of the nanofluid. According to the obtained results, the developed ANN model presents a reliable and efficient approach to estimate the viscosity of the MWCNT-TiO2-SAE50 oil nanofluid, eliminating the need for costly and extensive experimental measurements within the analyzed range. ANN could model the nanofluid viscosity with R2 = 0.9998 and MSE= 0.000189 that is quite acceptable. Also, the experimental data revealed that for the investigated nanofluid, temperature and shear rate have impressive effect on the viscosity (changing viscosity more than 100% for the analyzed margin), on the other hand, the nanoparticle volume fraction effect is much lower, to be more precise, increasing the nanoparticle percentage will increase the viscosity mean value around 30%.

Use of titanium dioxide doped multi-wall carbon nanotubes as promoter for the growth, biochemical indices of Sesamum indicum L. under heat stress conditions

The behavior of multi-walled carbon nanotubes (MWCNTs) and titanium dioxide nanoparticles (TiO2 NPs) as plant growth enhancers was still unclear; however, in this study, the effects of MWCNTs, TiO2NPs, 5%TiO2@MWCNTs, 10%TiO2@MWCNTs and 15%TiO2@MWCNTs on physical and biochemical contents in Sesamum indicum L. under heat stress conditions were studied. The content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) concentrations were reduced by the spraying MWCNTs and TiO2 NPs on plants. The hydrogen peroxide (H2O2) content was reduced by 49.02% in plants treated with 15%TiO2@MWCNTs while 42.14% reduction was found in plants treated with 10%TiO2@MWCNTs. The proportion of oil and the peroxidase enzyme activity in plants treated with 15%TiO2@MWCNTs were increased by 48.99%, for the oil content, and 2.39 times for POD activity respected to the stressed plants. The proportion of unsaturated fatty acids increased in plants treated with 15%TiO2@MWCNTs, 10%TiO2@MWCNTs and TiO2 NPs by 2.7, 2.52, and 2.09 times, respectively, greater than the control of the Shandweel-3 variety. Finally, plants treated with 15%TiO2@MWCNTs showed increases in seed yield and weight 1000-seeds by 4.42 and 1.67 times, respectively. These findings suggest that TiO2@MWCNTs more effective than separated MWCNTs and TiO2 NPs in improve plant growth. In addition, the cultivar Shandweel-3 showed an improvement in growth indicators more than the Giza-32 cultivar.

Mechanical and tribological behaviors of MWCNT/polyimide nanocomposites under drift of glass transition temperature

Herein, the tribological behavior of multi-walled carbon nanotube (MWCNT)/polyimide (PI) composites in water was investigated based on manufacturing optimization using response surface methodology (RSM). Wear surfaces and transfer films were analyzed by SEM, EDS, TEM, and Raman spectroscopy. It indicates that the molding process for neat PI and MWCNT/PI is deeply subjected to a narrow processing temperature window. Depending on the positive drift of the glass transition temperature for MWCNT/PI, the tribological properties in water were significantly affected by molding temperature. Besides, combined with experimental results and simulation analysis, it suggested that MWCNT performs rolling and/or sliding motions in molecular bearings form between frictional pairs for enhanced lubrication.

Adsorptive behavior of multi-walled carbon nanotubes immobilized magnetic nanoparticles for removing selected pesticides from aqueous matrices

The present work synthesized two new materials of functionalized multi-walled carbon nanotubes (MWCNT–OH and MWCNT–COOH) impregnated with magnetite (Fe3O4) using solution precipitation methodology. The resulting MWCNT–OH–Mag and MWCNT–COOH–Mag materials were characterized by scanning electron microscopy coupled with energy dispersion X-ray spectroscopy, Fourier transform infrared, X-ray diffraction, atomic force microscopy, and electrical force microscopy. The characterization results indicate that the –OH functional groups in the MWCNT interact effectively with magnetite iron favoring impregnation and indicating the regular distribution of nanoparticles on the surface of the synthesized materials. The adsorption efficiency of the MWCNT–OH–Mag and MWCNT–COOH–Mag materials was tested using the pollutants 2,4-D and Atrazine. Over batch studies carried out under different pH ranges, it was found that the optimal condition for 2,4-D adsorption was at pH 2, while for Atrazine, it was found at pH 6. The rapid adsorption kinetics of 2,4-D and Atrazine reaches equilibrium within 30 min. The pseudo-first-order model described 2,4-D adsorption well. The General-order model described better atrazine adsorption. The magnetically doped adsorbent functionalized with –OH surface groups (MWCNT–OH–Mag) demonstrated superior adsorption performance and increased Fe-doped sites. The Sips model described the adsorption isotherms accurately. MWCNT–OH–Mag presented the greatest adsorption capacity at 51.4 and 47.7 mg g−1 for 2,4-D and Atrazine, respectively. Besides, electrostatic forces and complexation rule the molecular interactions between metals and pesticides. The leaching and regeneration tests of the synthesized materials indicate high stability in an aqueous solution. Furthermore, experiments with wastewater samples contaminated with the model pollutants indicate that the novel adsorbents are highly promising for enhancing water purification by adsorptive separation.

Electric impedance investigation with inductive behavior of multiwalled carbon nanotubes doped with variable loadings of magnetite

Electric impedance investigation with inductive behavior of multiwalled carbon nanotubes doped with variable loadings of magnetite

Multiwalled carbon nanotubes as an additive to Mg-Mg2Si in situ composite obtained by powder sintering

This paper reports on the possibility of applying carbon nanotubes as an additive to metallic materials, where a new phase forms in situ from the powder mixture. Multi-walled carbon nanotubes (MWCNT) amounts of 1 vol% and 3 vol% were applied to synthesize a composite with interpenetrating phases obtained from magnesium microsized powder and nanosized silicon (n)Si by sintering under vacuum. In the experiments, two ordered Mg-(n)Si-MWCNT powder mixtures with a (n)Si: MWCNT ratio of 2: 1 were prepared by sonication. The effects of Mg2Si silicide in situ synthesis on the behavior of MWCNTs and the Mg2Si and Mgα morphology were studied. Using LM with quantitative metallography, SEM with EDS, XRD, HREM, it was found that the MWCNTs were a component of the skeleton formed by submicron and nanosized Mg2Si, MgO, and Mgα mixture. Non-agglomerated MWCNTs were also found in microsized Mg2Si particles in the composite. A decrease in the silicide crystallite size was also observed compared with material without a carbon nanocomponent. The transformation of MWCNTs into another phase or their morphology change was not observed. Therefore, the effects described in this paper can be adapted to technologies focused on different types of composites and for designing Mg2Si-based thermoelectric materials and intermetallic alloys.

Tribological behaviour of multi-walled carbon nanotubes reinforced AA 7075 nano-composites

ABSTRACT Carbon nanotubes (CNTs) play a major role in the development of new materials for high temperature, high strength, and better wear properties. In this paper, multi-walled carbon nanotubes (MWNTs) were reinforced with AA7075composites through a powder metallurgy route. The powders were consolidated using a uniaxial press at 400 MPa and followed by sintering at 5800°C in an argon atmosphere. The composites were characterised by XRD and FESEM, and microhardness of the compound was calculated by Vickers hardness tester. Wear and friction experiments were performed using a pin on a friction style disc and a data gathering equipment in accordance with ASTM G99 standard. The effect of sliding interface temperature on friction and wear behaviour was reported. The wear rate and friction coefficient of composites worsen with increasing carbon nanotube concentration. In comparison to the AA7075 matrix without reinforcement, AA7075/MWNTs composites have a moderate wear rate and a lower coefficient of friction; the optimal MWNTs content is 1 wt%. Wear properties of AA7075/MWNTs composites were improved compared to AA7075 alloy at Room temperature, 1000°C, and 2000°C temperatures.

Experimental and statistical investigation on the wear and hardness behaviour of multiwalled carbon nanotubes reinforced copper nanocomposites

In this experimental work the two parameter Weibull distribution statistical method is used to investigate the effect of fabrication process on the wear and hardness properties of multiwalled carbon nanotubes reinforced copper nanocomposites (MWCNTs/Cu). The MWCNTs/Cu nanocomposites are fabricated by the powder metallurgy processing route in two ways (i) MWCNTs/Cu nanocomposites without hot pressing (NHP-MWCNTs/Cu) and (ii) MWCNTs/Cu nanocomposites with hot pressing (HP-MWCNTs/Cu). The MWCNTs doping weight percentage (wt.%) include 0.0 (Pure copper), 0.5, 1.0 and 1.5. The MWCNTs/Cu nanocomposites are subjected to hardness and wear tests using micro-Vickers hardness tester and rotating type pin-on-disc tribometer, respectively. From the experimental results it is found that the MWNTs/Cu nanocomposites have higher hardness and lower wear rate than the pure Cu. Further, the HP-MWCNTs/Cu nanocomposites showed higher hardness and lower wear rate than the NHP-MWCNTs/C nanocomposites. From statistical analysis it is found that the HP-MWCTs/Cu nanocomposites showed more reliable and repeatable experimental data than the NHP-MWCNTs/Cu nanocomposites. Statistical analysis showed that the effectiveness of MWCNTs doping on the wear rate of Cu is more effective at lower sliding speed. Finally, it is observed form the statistical analysis that both theoretical and experimental results of hardness and wear tests showed good correlation.

Buckling Behavior of SWCNTs and MWCNTs Resting on Elastic Foundations Using an Optimization Technique

This paper aims to investigate the buckling behavior of multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) embedded in an elastic medium using the nonlocal cylindrical shell theory. The SWCNT is treated as a cylindrical shell and the MWCNT is considered as multiple SWCNTs nested inside one another; they interact with each other via van der Waals interactions. The interaction between the matrix and the outer wall is modeled as a foundation using Winkler, Pasternak, and Kerr models. An optimization technique is developed to estimate the nonlocal critical buckling load of SWCNT and MWCNT. Furthermore, analytical formulas are proposed to describe the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effect of the nonlocal parameter. In the proposed formulas, van der Waals interactions between adjacent tubes and the effect of terms involving tube radii differences are taken into account, although they are generally neglected in expressions published in the literature. The effects of the number of layers, the nonlocal parameter, and the elastic foundation parameters are investigated. Moreover, the effects of different parameters on the stability behavior of the carbon nanotubes are also discussed.

Effects of seawater corrosion environment on the impact behavior of multi-walled carbon nanotube and SiO2 reinforced basalt/epoxy hybrid nanocomposites

In this study, the impact behaviors of nano silica (SiO2 nanoparticles), MWCNTs (multi-walled carbon nanotube), and SiO2+MWCNTs (nano silica vs multi-walled carbon nanotube hybrid) nanoparticle additives in basalt fiber reinforced composites exposed to seawater corrosion were investigated. The Mediterranean was chosen as the corrosive sea water due to its high salinity. Basalt fiber reinforced composites immersed in seawater have quick mass absorption during the first 30 days. However, it can also vary between the first 28 and 40 days depending on the structure of the composite and environmental conditions. Immersion times were determined as 0, 10, 20, and 40 days. Tensile and low velocity impact tests were performed to evaluate the mechanical performance after seawater corrosion. Low velocity impact tests were carried out at 10 and 20 J energy levels. The aim of this study was to examine the effects of corrosion caused by quick mass absorption on the tensile and impact behaviors of basalt fiber reinforced composites. And also to investigate the contribution of SiO2 and MWCNT nanoparticle additives to the mass absorption mechanism and mechanical performance of basalt fiber reinforced composites. SiO2 and MWCNT nanoparticle additives increased the tensile and impact strength of basalt fiber reinforced composites. However, the tensile and impact behaviors of nanoparticle filled and nanoparticles unfilled basalt fiber reinforced composites were adversely affected by the seawater corrosion environment. Due to the geometric structure of SiO2 nanoparticles, the best mechanical performance was observed in SiO2 filled basalt fiber reinforced composites.

Thermophysical and tribological behaviors of multiwalled carbon nanotubes used as nanolubricant additives

This study investigates the thermophysical and tribological characteristics of engine oil (SAE 10W-40) using multiwalled carbon nanotubes (MWCNTs) as nanolubricant additives. The MWCNT additives based nanolubricant were formulated using an ultrasonic probe. The tribological performances of MWCNTs nanolubricant were evaluated by a reciprocating platform that simulated the piston ring and cylinder liner interface under various circumstances (i.e., contact loads and sliding velocity). The thermophysical performances of MWCNTs nanolubricant were evaluated using ultraviolet-visible spectrometry, Brookfield viscometers, a thermal conductivity meter, and thermogravimetric analysis. Furthermore, the wear mechanisms of the frictional surfaces were supported by field emission scanning electron microscopy and energy dispersive spectrometer. Critically, the flow characteristics of MWCNTs nanolubricant samples displayed non-Newtonian (shear-thinning) behavior, but the behavior of SAE 10W-40 oil was similar to Newtonian fluids. The friction coefficient decreased by 4%–34% and 26%–32% at different loads and speeds. Moreover, the specific wear rate of the ring and liner surfaces decreased by 29% and 40%, respectively, at 240 N load and 0.33 m s−1 velocity after a sliding distance of 22.57 km. These results suggest that MWCNT additives based nanolubricant effectively lubricated the mechanical applications.

The Effect of Hydrothermal Aging on the Low-Velocity Impact Behavior of Multi-Walled Carbon Nanotubes Reinforced Carbon Fiber/Epoxy Composite Pipes

The Effect of Hydrothermal Aging on the Low-Velocity Impact Behavior of Multi-Walled Carbon Nanotubes Reinforced Carbon Fiber/Epoxy Composite Pipes

Constitutive Modeling of Nonlinear Rheological Behavior of Carbon Nanotube-Filled Polypropylene Nanocomposites

Abstract The rheological behavior of multi-walled carbon nanotube (MWCNT)-filled polypropylene (PP) nanocomposites with different filler loadings was experimentally studied and simulated using constitutive modeling. Rheological behavior was characterized in small amplitude oscillatory shear (SAOS) flow, large amplitude oscillatory shear (LAOS) flow, startup of shear flow, steady shear flow, and stress relaxation after the imposition of a step shear strain. Virgin PP and PP with CNT loadings of 1, 3, and 5 wt% were used. The formation of a rheological percolation network was observed at these loadings. The Leonov and Simhambhatla-Leonov models were used to simulate the rheological behavior. In the linear region, the simulations provided good predictions of the experimental data for both the unfilled and filled PP. In the nonlinear region, the simulations also provided good results for the virgin PP and satisfactory results for the PP/1 wt%CNT nanocomposite under most flow conditions. However, for the other two nanocomposites the model showed mixed results.

Transport of surface-modified multi-walled carbon nanotubes in saturated porous media.

Carbon nanotubes (CNTs) are widely used and may pose potential environmental risks to soil and groundwater systems. Therefore, it is important to improve current understanding of the fate and transport of CNTs in porous media. In this study, the transport behavior of multi-walled carbon nanotubes (MWCNTs) with different surface modifications were examined in water-saturated sand columns under different pH (5 and 7) and ionic strength (0.1, 1, and 5mM) conditions. COOH-MWCNTs have the strongest mobility among the five types of MWCNTs, followed by pristine MWCNTs. NH2-MWCNTs, Cu-MWCNTs, and Fe-MWCNTs have the weaker mobility. The transport of five types of MWCNTs decreased with the increase of ionic strength, while increased with the increase of pH value. The results suggested that the transport of MWCNTs can be affected by the electrostatic attraction between the functional groups on the surface of MWCNTs and quartz sand. Moreover, the pH and ionic strength of the solution also played an important role in enhancing the transport of MWCNTs, which have great significance for evaluating the transport and fate of MWCNTs in natural environment.

Effect of functionalization on the electrochemical behavior of multi-walled carbon nanotube and parafilm nanocomposites

Soft, flexible and conductive interfaces are in high demand in wearable electronics where it can be used as electrode material integrated with commercial electronic components and living system. In the present study, we have developed flexible nanocomposites of multi-walled carbon nanotubes (MWCNTs) with parafilm (PF) thermoplastic. As the presence of carboxylic functionalization (─COOH groups) at MWCNT surface improves their dispersion properties, pristine MWCNTs (p-MWCNT) were oxidized to produce functionalized multi-walled carbon nanotubes (f-MWCNT) and it was further used as conductive filler. Characterization and comparison of morphological, physical, chemical and electrochemical properties of p-MWCNT, f-MWCNT, p-MWCNT-PF nanocomposite film and f-MWCNT-PF nanocomposite film was done using SEM, FTIR, RAMAN spectroscopy, TGA and electrochemical studies. The results suggest that chemical oxidation of p-MWCNT majorly generates carboxylic functions at the p-MWCNT surface which decreases as f-MWCNT embeds in the PF matrix. The f-MWCNT-PF nanocomposite films are thermally more stable as compared to p-MWCNT-PF nanocomposite films. Chemical oxidation treatment generates graphitic defects facilitating electron transfer process and higher conductivity at the f-MWCNT-PF nanocomposite film electrode surface. We believe that the comprehensive performance of soft and flexible f-MWCNT-PF nanocomposite films offers a unique and effective way to develop electrochemical platform for biosensor fabrication in wearable applications.

Effect of multiwalled carbon nanotubes on densification behaviour of multiwalled carbon nanotube and fly ash reinforced aluminium composites

The densification and compression behaviour of multi-walled carbon nanotubes (MWCNT) and flyash (FA) reinforced composites fabricated by powder metallurgy method were analysed. MWCNTs (0.25,0.5,0.75 wt%) and FA (4 wt%) were blended with aluminium matrix using ball milling technique and compacted at loads of 100,120 and 140 kN and sintered at 500 °C for 6 h under argon atmosphere. Experimental results show that density and hardness increased with the compaction pressure. Microstructural observations revealed good bonding between particles. Compression strength test revealed improved compression properties over unreinforced matrix material.

Investigation on mechanical properties of reinforced glass fibre/epoxy with hybrid nano composites

In this study the experimental investigation of mechanical behaviour of Multi-Walled Carbon nanotubes (MWCNTs) and Aluminium Oxide (Al2O3) reinforced with EGlass/Epoxy nanocomposites at 0.5%, 1.5% and 2.0% of weight rated with 225 GSM, 300 GSM and 450 GSM glass fibres were studied. Test specimens were prepared at the standardof ASTM D638 for tensile specimen ASTM D256 for impact specimen. Testspecimens were prepared at the ratio of MWCNTs: Al2O3 is 1:4. 1.5 wt. % of MultiWalled CNTs filledE-Glass/Epoxy nanocomposites showed improved mechanical properties than glass fiber reinforced epoxy composites.450 GSM reinforced glass fiber epoxy composites containing 1.5wt. % of MWCNTs improved 36.27 % of higher tensile value and 28.57 % of impact value than the glass fibre reinforced epoxy composites. 225 and 300 GSM reinforced glass fibre epoxy composites with 1.5 wt. % of MWCNTs composites also has improved tensile and impact value than glass fibre reinforced epoxy composites. But, overall 450 GSM reinforced fibre nanocomposites showed enhanced mechanical properties than the other GSM reinforced nanocomposites. This proves MultiWalled Carbon Nanotubes is a successful reinforcement for E-Glass/Epoxy matrix and it improves its properties and performance.

Influences of carbon nanotubes on low velocity impact performance of metallic nanocomposite plates – A coupled numerical approach

Low velocity impact behavior of multi-walled carbon nanotube (MWCNT)-aluminum (Al) nanocomposite plates are investigated. The rule of mixture is employed to obtain the material properties of the nanocomposites. The microstructural features, including amount, aspect ratio, alignment, waviness, and agglomeration of the MWCNTs are considered. The finite element method is used to investigate the plate dynamic behavior. Addition of the MWCNTs increases the contact force and decreases both the plate center deflection and impact duration. A higher volume fraction, higher aspect ratio, straight shape, and a uniform dispersion of MWCNTs can cause a lesser center deflection of the nanocomposite plates.