Characterization Of Multi-walled Carbon Nanotubes Research Articles

Exploring the Structural and Dielectric Properties of Polymer Films Incorporating Carbon-Based Nanomaterials

This work explores the electrical, dielectric and physical characteristics of multi-walled carbon nanotube (MWCNT) and graphene reinforced Poly vinylidene fluoride (PVDF) polymer nanocomposite films, over a wide frequency range, ranging from 1 Hz to 1 MHz. Films are prepared with different weight percentage of MWCNTs or graphene powder within a PVDF host matrix and its intrinsic properties are compared with pure PVDF films. As the weight percentage increases, the material properties such as conductivity (electrical), permittivity (dielectric) and capacitance (dielectric) will change. PVDF is a dielectric and the fillers are conductors, and this gives rise to the phenomenon of percolation, as the weight percentage of conducting fillers increases. This paper explores film’s properties for different weight percentage of MWCNTs and graphene fillers. Tunneling current of graphene–PVDF films are also compared with MWCNT–PVDF films.

Electroconductive nylon-6/multi-walled carbon nanotube nanocomposite for sodium sensing applications

Developing smart fabric materials that can withstand stress, strain, and bending is a key factor to successful integration into smart clothing. The aims of this study were (1) development and characterization of multiwall carbon nanotube (MWCNT)- based electroconductive materials for sensing applications, (2) optimization of experimental fabrication parameters to sensor response, (3) optimization of experimental fabrication parameters for mechanical properties. Nylon-6/MWCNT nanocomposites have enhanced mechanical and electrical properties which make them an ideal candidate for integration into smart clothing. Nylon-6/MWCNT nanocomposites were fabricated by functionalizing an electrospun Nylon-6 scaffold for selective sodium detection. Selective sodium detection is realized using a calixarene functionalization of the MWCNT and the MWCNT is only responsible for increased charge transfer of the nanocomposite. Initially, three factors were considered for optimization of nylon-6/MWCNT nanocomposite fabrication: nanotube type, nanotube concentration, and the weight percent of nylon in the electrospinning solution. The sensing nanocomposite materials were characterized for the electrical and mechanical properties. The sensitivity of the sensor to changing sodium ion concentration (µA/mM) was optimized for 20wt% nylon-6 nanofiber base functionalized in a solution of 0.5 mg/mL of CNT. The optimized sensor has a nanotube length less than 0.2 µm and fiber diameter ranging between 0.25–0.32 µm. The target-controlled coat weight is 20 GSM (g/m2) for electrospun nylon nanofibers. Secondly, the impact of electrospinning conditions, particularly flow rate, on sensor response was considered. Sensor materials produced at an electrospinning flow rate of 1.0 mL/min had an enhanced stress at break, compared to neat nylon-6, without sacrificing elasticity. Additionally, sensors produced at electrospinning flow rates of 1.0 mL/h maintain their sensor response for approximately 20 stretches with no statistical difference between sensor response of the stretched and unstretched sensors.

Synthesis and characterization of MWCNT-supported iron phthalocyanine catalyst for the treatment of wastepaper recycling mill wastewater using microbial fuel cell

This study reported that the preparation and characterization of multiwalled carbon nanotubes supported iron phthalocyanine (FePc/MWCNTs) composite catalyst and examined the treatment efficiency using wastepaper recycling mill wastewater in a microbial fuel cell (MFC). The MWCNTs were uniformly decorated over the FePc nano particles. The obtained catalyst was characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction analysis, UV-visible spectrophotometry, energy-dispersive X-ray analysis (EDAX) Fourier-transform infrared spectroscopy (FTIR) analysis, BET analysis, Raman spectra, thermal gravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) analysis. In addition, the oxygen reduction reaction (ORR) of the catalyst has been investigated by cyclic voltammetry, linear sweep voltammetry analysis, and electrochemical impedance spectroscopy (EIS) analysis. There was an efficient removal of chemical oxygen demand (COD) with 87% and 0.650 W/m2 of power density achieved at 110 h of contact time. From this investigation, it is understood that the oxygen reduction reaction (ORR) of the FePc catalyst was improved by MWCNT supporting material. The obtained results suggested the excellent ORR activity of nanostructured FePc/MWCNTs as a promising alternative to conventional platinum-based electro catalyst for fuel cells.

Thermophysical properties of nanofluids MWCNT (multi-walled carbon nanotubes) in water for emergency coolant from nuclear reactors

To evaluate the synthesis and characterization of MWCNT (Multi-walled Carbon Nanotubes) with different degrees of functionalization in distilled water. The thermophysical properties (thermal conductivity and viscosity) of these nanofluids were measured at a temperature range (20-60°C) and concentrations (0.005-0.05%) by volume. Increases in thermal conductivity and viscosity were found 9.3% and 4.7%, respectively, at a volumetric concentration of 0.01% at a temperature of 30°C. The study of new fluids that improve the rate of removal of heat is fundamental to obtain greater efficiency of energy systems. Among the several factors that compromise the efficiency of the energy systems, we can highlight the thermophysical limitations of the conventional fluids, inhibiting in a very significant way some industrial applications. In this work we intend to improve the heat transfer characteristics of fluids commonly used by the addition of nanoparticles, made up of carbon nanotubes, in water which is the most used fluid for the cooling of nuclear reactors in operation today. It is intended to improve the heat transfer characteristics of fluids commonly used by the addition of nanoparticles, made of carbon nanotubes, through the addition of nanoparticles, made up of carbon nanotubes, in water which is the most used fluid for refrigeration of nuclear reactors currently in operation. In order to assess its benefits for the applicability and nuclear systems, ie primary coolant, safety systems, major accident mitigation strategies.

Synthesis and Characterization of Multi-walled Carbon Nanotube from Pine Oil and Their Impact on Carbon Fibre Reinforced Epoxy Hybrid Nanocomposite

Synthesis and Characterization of Multi-walled Carbon Nanotube from Pine Oil and Their Impact on Carbon Fibre Reinforced Epoxy Hybrid Nanocomposite

Synthesis and Characterization of Multiwalled Carbon Nanotubes (MWCNTs) Dispersed ZnS Based Photocatalytic Activity

Synthesis and Characterization of Multiwalled Carbon Nanotubes (MWCNTs) Dispersed ZnS Based Photocatalytic Activity

The effect of water cement ratio on the characteristics of multi-walled carbon nanotube reinforced concrete

Water Cement ratio play vital role in strength, durability and serviceability of concrete. In this study effect of water-cement ratio on the strength of multi walled carbon nano tube reinforced concrete is analyzed. Five concrete mixtures at different water-cement ratio (W/C) with and without carbon nano tubes (CNTs) were prepared. W/C of 0.40, 0.45, 0.48, 0.50 and 0.55 were used while quantity of carbon nano tube (CNT) was fixed at 1% by weight of cement (wbc). The workability of carbon nanotube reinforced concrete (CNTC) by was reduced by 39.57% while W/C = 0.48 was found ideal for slump as well as strength. At this W/C compressive strength for CNTC increased by 7.14%.

Synthesis and characterization of multi-walled carbon nanotubes decorated with hydroxyapatite

In this paper, multi-walled carbon nanotubes have been prepared at low synthesis temperatures and without high pressure by a simple chemical route. Fourier transformed infrared spectroscopy, Raman spectroscopy and X-ray diffraction analysis was used to determine the purity of the synthetized compound. Also, by transmission electron microscopy and atomic force microscopy, a diameter between 9 nm and 43 nm and approximately 500–600 nm in length of multi-walled carbon nanotubes, was confirmed. Further, the multi-walled carbon nanotubes functionalized with negative charged functional groups (anionic groups) were decorated with hydroxyapatite by co-precipitation method. The decoration of multi-walled carbon nanotubes with hydroxyapatite was confirmed by transmission electron microscopy, Fourier transformed infrared spectroscopy and X-ray diffraction analysis. Also, energy-dispersive X-ray analysis proved the successfully obtaining of the nanocomposites. The simple method presented here may be extended to synthesize other composites based on coated multi-walled carbon nanotubes.

Chemical Synthesis, Functionalization and Characterization of Multiwalled Carbon Nanotubes

This research work is attempted to synthesize, functionalize and to characterize multi walled carbon nanotubes (MWCNTs). The synthesis of multi walled carbon nanotubes was done by chemical vapor deposition (CVD) method. The characterization of MWCNTs was done by adopting the following techniques such as field emission scanning electron microscope, X-ray diffraction, Fourier-transform infrared spectroscopy. The crystalline quality of MWCNTs was confirmed from the analysis of X-ray diffraction pattern. FE-SEM image obtained for MWCNTs and functionalized MWCNTs and it has been seen that dimeter of most of the MWCNTs lies around 90 nm, where as, functionalized MWCNTs diameter is smaller i.e., around 35 nm only. Fourier-transform infrared spectroscopy study confirmed the presence of –COOH and H- bonded –OH in functionalized MWCNTs.

Synthesis and characterization of multi-walled carbon nanotubes from silkworm cocoons to use as the cathode material for Al-air battery

ABSTRACT Carbon nanotubes have been synthesized by chemical vapor deposition at 850°C using silkworm cocoons as a precursor. The impregnation method with 3 wt% ferrocene as a catalyst was utilized for growth of carbon nanotubes. The flow rates of C2H2, H2, and N2 were fixed at 100, 150, and 350 ml/min, respectively. Morphology, microstructure and quality of the synthesized carbon nanotubes were investigated by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques. Results showed that the prepared carbon nanotubes were multiwalled and good graphitic quality. When used as the cathode material for aluminum-air battery, prepared carbon nanotubes cathode exhibited higher current density than commercial graphite cathode. Based on our study, there is a successful conversion of silkworm cocoons into value-added nanomaterial products, promoting the natural biotechnological materials.

Dry sliding wear characteristics of multi-walled carbon nanotubes reinforced Al-Si (LM6) alloy nanocomposites produced by powder metallurgy technique

The present work involved the production of Metal Matrix Composites (MMCs) of Aluminium Silicon (Al-Si) alloy reinforced with Multi Walled Carbon Nano Tubes (MWCNTs) using Powder Metallurgy (PM) process. MWCNTs with concentrations of 0, 0.25, 0.5, 0.75 and 1.0 wt% were used. Validation of dispersion nature, existence and chemically stable of MWCNTs carried out using Transmission Electron Microscope (TEM), X-ray Diffractometer (XRD) and Energy Dispersive Spectrum (EDS) for fabricated composites. Sliding wear investigations were investigated in accordance with the ASTM G99-95a standard. Test variables such as sliding distance, load and speed were examined. Under a given load with sliding distance, the wear rate was found to reduce by varying disc rotation speed between 250 to 750 rpm. The rate of wear is dropped suddenly with the increment in sliding distance from 500 m to 1000 m. However, for 1500 m sliding distance, the wear rate increased linearly for all nanocomposites. The reinforcement of 0.25 wt% and 0.5 wt% of MWCNTs shown lower wear resistance and further addition of 0.75 wt% MWCNTs shown enhanced wear resistance but the addition of reinforcement of above 0.75 wt% resulted in slightly higher wear rate. The wear resistance enhanced due to the excellent properties of reinforcement particles. The Scanning Electron Microscope (SEM) was used for identifying the kind of wear mechanism.

Barothermal Diels-Alder functionalization of multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) have an ordered geometric structure, large specific surface area, prominent electrical conductivity, and unique mechanical properties. They are nontoxic and can be used in biomedicine. Physical and surface chemical characteristics of MWCNTs should be tuned to that required to improve certain properties and obtain a variety of functional materials. We modified the MWNTs by using the barothermal Diels-Alder reaction with dienophiles, p-benzoquinone, fumaronitrile, and maleimide, to address this issue. The prepared MWCNTs were studied by SEM-EDX, nitrogen adsorption porometry, ATR FTIR, and thermal analysis. Results showed that both separate and conjugated C = C bonds at the edge and outer/inner surface of walls could react with dienophiles. The grafted groups are separated by the temperature on weak (low-temperature) and strong (high-temperature) chemisorbed forms; they are detached at temperatures below and above 350 °C, correspondingly. Thermal analysis shows that up to 5% of the carbon atoms are involved in the [4 + 2] cycloaddition. The high-temperature forms of the grafted groups under extreme heating can be involved in the retro-Diels-Alder reaction that breaks six-membered rings, producing a dienophile.

Removal of anionic and cationic dyes from wastewater by adsorption using multiwall carbon nanotubes

This paper evaluated the efficiency and reusability of multiwall carbon nanotubes (MWNTs) on removal of cationic and anionic dyes under effect of pH, dose of MWNTs and concentration of dyes. The characterization of MWNTs is characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectra and BET (Brunauer, Emmett and Teller) surface area. SEM and TEM analyses showed that MWNTs had size within nano scale range of 10–50 nm. The experimental results indicated that the efficiency of removal of MWNTs increase under condition of normal pH, at contact time 60 min with agitation speed 240 rpm and initial concentration of dyes 10 mg/l. Under these optimal conditions, the removal reached 98.7% and 97.2% for anionic dyes and cationic dyes, respectively. For economic use, MWNTs can be used more than one time where the same experiments with the already used MWNTs was repeated and it was found that the percent removal is almost the same.

Fabrication and Characterization of MWCNTs by Syngas and Temperature Conditions

The morphologies, bulk densities, and synthesis yields of multi‐walled carbon nanotubes (MWCNTs) were analyzed by optimizing the catalyst, syngas, and synthesis temperature, which are key factors in the production of MWCNTs. In addition, MWCNTs were applied to polymer composites, and their electrical conductivities were evaluated through surface resistance measurements. The catalyst used in this process was a deposition precipitation method that offers favorable uniformity of loading through the liquid phase process and provides the advantage of controlling the shape using a support. Furthermore, physical and electrical analyses were performed in the range from 650 to 725°C using ethylene, butane, and liquefied petroleum gas (LPG) syngas. The results showed that the optimal synthesis yield and electrical conductivity of ethylene and butane were observed at 675°C, while those of LPG syngas were observed at 700°C. This implies that the aggregate diameter and bundle length tend to decrease under the most optimal conditions.

Study on mechanical and viscoelastic behavior of carbon nanotube (CNT) reinforced Epofine1564 nanocomposite

This paper presents an experimental study to examine the mechanical and viscoelastic characteristics of multi-walled carbon nanotubes (MWCNTs) reinforced epoxy nanocomposite. The nanocomposite samples of varying volume fractions are prepared using solution mixing technique. A two-step mixing procedure with magnetic stir and bath type ultra sonicator is employed to acquire well dispersion of CNTs in epoxy resin. Three-point bending, tensile and impact tests are conducted on the prepared samples to measure the elastic modulus, strength and failure strain respectively. The morphological analysis of fractured samples is carried-out under field emission scanning electron microscopy (FESEM). The dispersion and reinforcing mechanism of CNTs within the polymer matrix are observed. The results show that a small amount of CNTs in a polymer matrix improves the stiffness and strength of the composite considerably. The agglomeration occurs beyond the 0.5 wt% of CNTs. Furthermore, towards thermal stability analysis, the improvement of viscoelastic characteristics with the addition of MWCNTs is studied using dynamic mechanical analysis test. Results are shown in the form of graphs and tables.

Synthesis and characterization of multiwalled carbon nanotubes supported LaxCa1−xMnO3 (x = 0.2, 0.3)

Multiwalled carbon nanotubes (MWCNTs) supported LaxCa1−xMnO3 (x = 0.2, 0.3) were synthesized via wet impregnation method, calcined at 450 °C and under vacuum oven at 200 °C for six hours. The x-ray diffraction (XRD) analysis inferred the presence of carbon within parent crystal orientation of LaCaMnO3 in synthesized MWCNT/LaxCa1−xMnO3 (x = 0.2, 0.3). Compositional analysis and binding energies profile of elements presents in synthesized samples was studied via x-ray photoelectron spectroscopy (XPS). Maximum output power density of La0.2Ca0.8MnO3/MWCNTs and La0.3Ca0.7MnO3/MWCNTs was found to be 277 mW cm−2 and 151 mW cm−2 at 600 °C observed from fuel cell data.

Investigation of adsorption properties of levulinic acid by a nanotechnological material

In this present work, levulinic acid was adsorbed from aqueous solutions by a nanotechnological material, namely multiwall carbon nanotube (MWCNT). The aim of this work is to determine the adsorption capacity of MWCNT at the different experimental conditions for levulinic acid uptake. The characterization of MWCNT was analyzed by FTIR and SEM. The equilibrium and kinetic adsorption experiments were performed on batch type. In these experiments, important parameters on affecting adsorption such as contact time (30–210 min), initial acid concentration (2–10%, w/w), temperature (25–45 °C) and adsorbent dosage (0.01–0.03 g) were investigated. In the kinetic experiments, the equilibrium time was determined as 120 min. In the equilibrium studies, the adsorption capacity values of MWCNT for the adsorption of levulinic acid increased from 68.27 mg g−1 to 483.25 mg g−1 at 25 °C with increasing the initial acid concentration. Langmuir, Freundlich and Temkin isotherm parameters were calculated as depended on initial acid concentration. Kinetic models such as Elovich, pseudo-first order, pseudo-second order and Weber-Morris intra-particular diffusion model were also applied to kinetic experimental results.

The influence of treatment time on multi-walled carbon nanotubes functionalized by poly(ethylene glycol)

The paper reports an influence of treatment duration on the characteristics of multi-walled carbon nanotubes (MWCNTs) functionalised by poly(ethylene glycol) (PEG) for the first time. MWCNTs covalently functionalised with PEG (MWCNTs-PEG) are successfully prepared and characterised by several techniques including FE-SEM, EDX, Raman spectroscopy and TGA. The FE-SEM images show that an average tube diameter of the MWCNTs-PEG is increased by 21% in comparison to pristine MWCNTs. According to the TGA analysis and EDX measurements, the highest weight loss of 21.31 wt% and the highest ratio of oxygen to carbon (O/C) of 22.26 % are simultaneously achieved for the treatment time of 6 h. The results allow us to conclude that the optimum time to obtain the best functionalisation result is 6 h.

Role of interface on damping characteristics of multi-walled carbon nanotube reinforced epoxy nanocomposites

In this report, we propose an experimental approach to determine the role of the epoxy-CNT interface on damping by designing two systems of composites which differ in the interfacial area. The composites are namely ‘dispersed’ and ‘layered’. The CNTs were uniformly distributed in the epoxy matrix of the dispersed nanocomposites. Whereas, in the layered nanocomposite, a layer of CNT was sandwiched between two epoxy sheets. Image threshold technique was adopted to characterize the CNT spread area in the epoxy matrix. The epoxy-CNT interfacial area is assumed to be less than the CNT spread area due to the agglomeration of CNTs. The CNT spread area of dispersed nanocomposites was found to be 30 times higher than that of the layered composite. In addition to this, it is observed with microstructure analysis using scanning electron microscope and transmission electron microscope that the dispersed nanocomposites were comprised of more epoxy-CNT interfaces, and the layered nanocomposites have more CNT-CNT interfaces. At a particular CNT content, at the glass transition temperature, higher dynamic loss factor was characterized with dispersed nanocomposites. The energy dissipating nature of the epoxy-CNT and CNT-CNT interfaces were studied by analyzing the microstructural mechanisms of damping related to the system of composites dealt with this study.

Enhanced SO2 sensing characteristics of multi-wall carbon nanotubes based mass-type sensor using two-step purification process

In this work, a room temperature gas sensor based on functional multi-wall carbon nanotubes (MWNTs) coated quartz crystal microbalance (QCM) was developed. The two-step purification process was used to remove amorphous carbon and inactivated catalyst particles, and added functional groups on the sidewall of tubes. The functional MWNTs were then dispersed in deionized water to deposit on the gold electrode of the QCM. The operative MWNTs-coated QCM sensor was tested with toxic hazardous gases such as hydrogen sulfide, hydrogen, nitrogen dioxide, carbon monoxide, and sulfur dioxide. The sensing results expose that the fabricated sensor exhibits good sensitivity with sulfur dioxide gas at room temperature. The sensitivity of the functional MWNTs based sensor presented to be superior to that of the as-grown MWNTs based sensor.