Electric Field Effects on Self-Organization Processes during Droplet Evaporation of Multiwall Carbon Nanotube Aqueous Suspension

2018 ◽  
Vol 936 ◽  
pp. 25-30
Author(s):  
A.P. Kuzmenko ◽  
N.A. Khokhlov ◽  
Thet Phyo Naing ◽  
Myo Min Than
Keyword(s):  
Carbon Nanotubes ◽  
Electric Field ◽  
Aqueous Suspension ◽  
Multiwall Carbon Nanotubes ◽  
Droplet Evaporation ◽  
Self Organization ◽  
Uniform Electric Field ◽  
Multiwall Carbon Nanotube ◽  
Walled Carbon Nanotubes ◽  
Multiwall Carbon

The self-organization of COOH-functionalized multiwall carbon nanotubes (MWCNTs) during droplet evaporation of their aqueous suspension in a constant uniform electric field (E) was investigated. It was established that the COOH-functionalization polarizes the MWCNTs in the transverse direction to their axis. Depending on their size, MWCNTs tended to agglomerate into three different stable structures in different drop regions. There were linear, fractal and cluster structures (LS, FS, and CS). Sizes of the FSs decreased as 1/Е, whereas the rate of their growth increased as Е2. The single-walled carbon nanotubes (SWCNTs) were found inside the LSs and CSs. The chiral indices of the SWCNTs were determined, corresponding to metallic and semiconducting conductivities. An analysis showed that as a result of coagulation and amassment of the carbon nanotubes (CNTs) near electrodes, there were formed conductive regions. When the concentration of MWCNTs reached some value in part nearest to an electrode, this part became conductive. The positive and negative electrodes, formed now by MWCNTs, shifted towards each other. The observed effects show that considered self-organization is controllable by the electric field.

Electroless Coating of Silver on Multiwall Carbon Nanotubes

2012 ◽  
Vol 710 ◽  
pp. 774-779
Author(s):  
Niraj Nayan ◽  
S.V.S. Narayana Murty ◽  
S.C. Sharma ◽  
K. Sreekumar ◽  
Parameshwar Prasad Sinha
Keyword(s):  
Carbon Nanotubes ◽  
Surface Modification ◽  
Multiwall Carbon Nanotubes ◽  
Activation Process ◽  
Multiwall Carbon Nanotube ◽  
Effective Utilization ◽  
Electroless Coating ◽  
Silver Matrix ◽  
Electrical Brush ◽  
Multiwall Carbon

Silver reinforced with carbon nanotubes, instead of graphite, would increase both the electrical conductivity, hardness and wear resistance of the electrical brush materials. The effective utilization of carbon nanotubes in the Ag/CNT composite depends strongly on its uniform distribution and strong interfacial adhesion to the silver matrix and thus demands for its surface modification. In order to carry out the surface modification of carbon nanotubes, electroless coating was given to them after liquid phase oxidation, sensitization and activation process. The room-temperature chemical treatment results in a nominally complete coating over the entire outer surface of multiwall carbon nanotube. The surface morphology of the carbon nanotubes after each step has been studied using TGA, DSC, XRD, FTIR and SEM.

Optimization of Chemical Vapor Deposition Synthesis Conditions for Multiwall Carbon Nanotube by Statistical Analysis of Experiment

2008 ◽  
Vol 55-57 ◽  
pp. 533-536
Author(s):  
P. Saiprasert ◽  
D. Koolpiruck ◽  
S. Chiangga
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Multiwall Carbon Nanotubes ◽  
Statistical Design ◽  
Chemical Vapor ◽  
Multiwall Carbon Nanotube ◽  
Synthesis Conditions ◽  
Fourier Transform Raman ◽  
Multiwall Carbon

The optimization of chemical vapor deposition synthesis conditions for multiwall carbon nanotubes (MWCNTs) was experimentally investigated. Carbon nanotubes were grown on cobalt substrate thicknesses of 20, 100 and 1000 nm at 700 and 900 0C with 2 replications. The configuration and morphology of the carbon nanotubes were investigated by scanning electron microscope and Fourier transform raman spectrometer, respectively. The tendency of the parameters was evaluated by statistical design of experiment. Observations on samples produced under our optimised production process, showed that a large number of MWCNTs bundles were produced. Diameter of MWCNTs bundles ranges between 30 and 100 nm throughout the samples. From the variance analysis of the Raman spectra we observe that the thickness of cobalt and temperature of synthesis are highly significant in which the coherence length and innermost diameter increase for either the thickness increases or the temperature decreases.

scholarly journals AC Susceptibility Studies under DC Fields in Superspinglass Nanomaghemite-Multiwall Carbon Nanotube Hybrid

2021 ◽  
Vol 7 (4) ◽  
pp. 52
Author(s):  
Juan A. Ramos-Guivar ◽  
F. Jochen Litterst ◽  
Edson C. Passamani
Keyword(s):  
Carbon Nanotubes ◽  
Ac Susceptibility ◽  
Multiwall Carbon Nanotubes ◽  
Blocking Temperature ◽  
Multiwall Carbon Nanotube ◽  
Fe2o3 Nanoparticles ◽  
Different Temperatures ◽  
Fe2o3 Nanoparticle ◽  
Average Size ◽  
Multiwall Carbon

Magnetic properties of maghemite (γ-Fe2O3) nanoparticles grown on activated multiwall carbon nanotubes have been studied by alternating current (AC) magnetic susceptibility experiments performed under different temperatures, frequencies, and applied magnetic fields. Transmission electron images have suggested that the γ-Fe2O3 nanoparticles are not isolated and have an average size of 9 nm, but with a relatively broad size distribution. The activation energies of these 9 nm γ-Fe2O3 nanoparticles, determined from the generalized Vogel–Fulcher relation, are reduced upon increasing the direct current (DC) field magnitude. The large activation energy values have indicated the formation of a superspinglass state in the γ-Fe2O3 nanoparticle ensemble, which were not observed for pure γ-Fe2O3 nanoparticles, concluding that the multiwall carbon nanotubes favored the appearance of highly concentrated magnetic regions and hence the formation of superspinglass state. Magnetic relaxation studies, using Argand diagrams recorded for DC probe fields (<20 kOe) below the magnetic blocking temperature at 100 and 10 K, have revealed the presence of more than one relaxation process. The behavior of the ensemble of γ-Fe2O3 nanoparticles can be related to the superspinglass state and is also supported by Almeida–Thouless plots.

Diffusion of Multiwall Carbon Nanotubes into Industrial Polymers

2019 ◽  
Vol 23 ◽  
pp. 213-221
Author(s):  
Ponnusamy Senthil Kumar ◽  
A. Saravanan
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Polymer Chains ◽  
Carbon Particles ◽  
Mechanical Quality ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Multiwall Carbon ◽  
Weight Proportion ◽  
Carbon Molecule

Carbon nanotubes (CNTs) are made out of carbon atoms connected in hexagonal shapes, with every carbon molecule covalently attached to three other carbon particles. The properties of nanotubes have made scientists and organizations think about utilizing them in many fields. For instance, since carbon nanotubes have the most noteworthy quality to-weight proportion of any known material. Nanocomposites of adjusted multi walled carbon nanotubes (MWCNTs) installed in a polymer matrix yield a one of a kind mix of warm and electrical properties and mechanical quality. The composites combine the vast pseudo capacitance of the directing polymers with the quick charging/releasing two-fold film impedance and incredible machine-driven possessions of the carbon nanotubes. The electrochemically co-stored composites are the most homogeneous and demonstrate an unordinary communication between the polymer and nanotubes, offering ascend to a reinforced electron delocalisation and conjugation along the polymer chains

scholarly journals Incorporation of Functionalized Multiwall Carbon Nanotubes into a Polyurethane Matrix

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Martin Michálek ◽  
Michael Bredol
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Percolation Threshold ◽  
Aqueous Suspension ◽  
Sodium Dodecyl ◽  
Multiwall Carbon Nanotubes ◽  
Glass Substrates ◽  
Functionalized Mwcnts ◽  
Multiwall Carbon

Functionalized and raw multiwall carbon nanotubes (MWCNTs) were investigated colloid-chemically in order to study the role of polar versus nonpolar interaction with a polyurethane (PU) matrix. Both kinds of MWCNTs were dispersed by ultrasonication in the presence of a surfactant (sodium dodecyl sulphate) in aqueous solution. Functional groups on the nanotube surface were characterized by infrared spectroscopy and by theζ-potential in aqueous suspension. Such suspensions were added to waterborne PU dispersions, drop-cast on glass substrates and cured. The percolation threshold for electrical conductivity with polar (functionalized) MWCNTs was reached at 0.24 wt.%, whereas at concentrations as high as 2 wt.%, PU films with nonpolar MWCNTs stayed below the percolation threshold. With an addition of 0.4 wt.% polar MWCNTs, the electrical conductivity increased to >10−6 S/cm in the cured coating layer. These results are interpreted with respect to the chemical nature of the PU matrix.

Thermal conductivity and flammability of multiwall carbon nanotube/polyurethane foam composites

2016 ◽  
Vol 53 (2) ◽  
pp. 215-230 ◽  
Author(s):  
JJ Espadas-Escalante ◽  
F Avilés ◽  
PI Gonzalez-Chi ◽  
AI Oliva
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Polyurethane Foam ◽  
Fire Behavior ◽  
Multiwall Carbon Nanotubes ◽  
Propagation Speed ◽  
Interfacial Thermal Resistance ◽  
Multiwall Carbon Nanotube ◽  
Multiwall Carbon

The thermal conductivity and fire response of multiwall carbon nanotube/polyurethane foam composites are investigated for ∼45 kg/m3 foams with multiwall carbon nanotube concentrations of 0.1, 1, and 2 wt.%. The thermal conductivity of such nanocomposites shows a modest increase with increased multiwall carbon nanotube content, which is explained by a high value of interfacial thermal resistance, as predicted by existent thermal models. A strong correlation between multiwall carbon nanotube content, foam’s cellular morphology, and fire behavior was observed. The flame propagation speed increases with the addition of 0.1 wt.% multiwall carbon nanotubes and then reduces as the multiwall carbon nanotube content increases. The mass lost after flame extinction reduces with the addition of multiwall carbon nanotubes, suggesting an increased resistance to flame attack due the multiwall carbon nanotube presence.

Improved Selectivity of Oxidized Multiwall Carbon Nanotube Network for Detection of Ethanol Vapor

2011 ◽  
Vol 495 ◽  
pp. 83-86 ◽  
Author(s):  
Daniel Matejik ◽  
Robert Olejnik ◽  
Petr Slobodian ◽  
Petr Saha
Keyword(s):  
Aqueous Suspension ◽  
Multiwall Carbon Nanotubes ◽  
Ethanol Vapor ◽  
Solubility Parameters ◽  
Multiwall Carbon Nanotube ◽  
Hansen Solubility Parameters ◽  
Vapor Detection ◽  
Filtration Method ◽  
Carbon Nanotube Network ◽  
Multiwall Carbon

Two kinds of Multiwall carbon nanotubes (MWCNT) networks “Buckypaper” were made by the vacuum filtration method of MWCNT aqueous suspension. The first one was prepared from pure CNT and the second from its oxidized form by acidic KMnO4 as oxidizing agent. The CNT oxidation increase content of oxygen bonded to the surface of CNT decreasing their hydrophobic character. The sensitivity of MWCNT networks to two kind of organic solvent vapors (ethanol and hepane) has been investigated by resistance measurements. The solvents had different polarities given by Hansen solubility parameters and nearly the same volume fractions of saturated vapors at the condition of experiment. CNT oxidation significantly increases the sensitivity of CNT resistive sensor to vapors of ethanol and decrease response to heptane vapors. The present paper demonstrates the effective way how to add proper selectivity for organic vapor detection.

A Study on the Effects of Multiwall Carbon Nanotubes on Dynamic Stiffness of Hydrophilic-base Magnetorheological Gel

2019 ◽  
Vol 15 (3) ◽  
pp. 319-323 ◽  
Author(s):  
Young-Keun Kim ◽  
Jangheon Kim ◽  
Daeik Jang ◽  
Soohyun Kim ◽  
Wonsuk Jung
Keyword(s):  
Carbon Nanotubes ◽  
Vibration Control ◽  
Control Systems ◽  
Dynamic Stiffness ◽  
Multiwall Carbon Nanotubes ◽  
Silicon Oil ◽  
Multi Walled Carbon Nanotubes ◽  
Stiffness Variation ◽  
Walled Carbon Nanotubes ◽  
Multiwall Carbon

Background: Recently, addition of multi-walled-carbon-nanotubes (MWCNTs) has been researched to enhance the rheological properties of magnetorheological (MR) materials of fluid, elastomer and gel. However, there is a lack of study on the effects of MWCNTs on hydrophilic based MR gels (MRG), which have shown a high potential to be applied in smart vibration control systems. Objective: This study is aimed to analyze the effect of MWCNTs on the dynamic stiffness of hydrophilic based MRG. Method: Dynamic stiffness of hydrophilic based MRG was experimentally computed under different magnetic fields and strain amplitudes. Results: Experimental results indicate that the addition of MWCNTs in hydrophilic MRG showed overall degradation of stiffness variation in contradictory to similar research performed on silicon oil based MR gel. Conclusion: These contradictory results reveal that MRGs of hydrophilic base have a different interaction with MWCNTs than hydrophobic oil base.

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