WorldWideScience

Sample records for 2-aminophenoxazin-3-one-functionalized multiwalled carbon

  1. Carbon linear chains inside multiwalled nanotubes

    Cazzanelli, E.; Caputi, L.; Castriota, M.; Cupolillo, A.; Giallombardo, C.; Papagno, L.

    2007-09-01

    Multiwalled carbon nanotubes have been deposited on graphite cathodes by using an arc discharge technique in He atmosphere, with the insertion of a catalytic Ni-Cr mixture as well as without catalysers. The topography of such deposition has been investigated by SEM, while a parallel micro-Raman study has revealed, in particular regions of the deposited cathodes, strong bands in the range 1780-1860 cm -1, assignable to linear carbon chains inside the nanotubes. The variation of intensity, frequency and bandwidth of such bands has been investigated, in relation with the spectral characters of the host multiwalled carbon nanotube. In the cathode deposited without catalyst a quite ordered configuration of multiwalled carbon nanotubes is obtained in the central zone, while the maximum concentration of linear carbon chains is found in a ring shaped zone just inside the border. In sample obtained with catalyst the deposited multiwalled carbon nanotubes appear always more disordered, and a remarkable concentration of carbon chains appears in some zones, with a more casual distribution.

  2. Magnetoresistance of Multiwalled Carbon Nanotube Yarns

    SHENG Lei-Mei; GAO Wei; CAO Shi-Xun; ZHANG Jin-Cang

    2008-01-01

    We measure zero-field resistivity and magnetoresistance of multiwalled carbon nanotube yarns (CNTYs). The CNTYs are drawn from superaligned multiwalled carbon nanotube arrays synthesized by the low-pressure chemical vapour deposition method. The zero-field resistivity shows a logarithmic decrease from 2 K to 300 K. In the presence of a magnetic field applied perpendicular to the yarn axis, a pronounced negative magnetoresistance is observed. A magnetoresistance ratio of 22% is obtained. These behaviours can be explained by the weak localization effect.

  3. Degradation of multiwall carbon nanotubes by bacteria

    Understanding the environmental transformation of multiwall carbon nanotubes (MWCNTs) is important to their life cycle assessment and potential environmental impacts. We report that a bacterial community is capable of degrading 14C-labeled MWCNTs into 14CO2 in the presence of an external carbon source via co-metabolism. Multiple intermediate products were detected, and genotypic characterization revealed three possible microbial degraders: Burkholderia kururiensis, Delftia acidovorans, and Stenotrophomonas maltophilia. This result suggests that microbe/MWCNTs interaction may impact the long-term fate of MWCNTs. Highlights: •Mineralization of MWCNTs by a bacterial community was observed. •The mineralization required an external carbon source. •Multiple intermediate products were identified in the MWCNT degrading culture. •Three bacterial species were found likely responsible for MWCNT degradation. -- The 14C-labeled multiwall carbon nanotubes can be degraded to 14CO2 and other byproducts by a bacteria community under natural conditions

  4. Coulomb drag in multiwall armchair carbon nanotubes

    Lunde, A.M.; Jauho, Antti-Pekka

    2004-01-01

    We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...

  5. Multiwalled carbon nanotube: Luttinger versus Fermi liquid

    Tarkiainen, R.; Ahlskog, M; Penttilä, J; Roschier, L.; Hakonen, Pertti J.; Paalanen, M.; Sonin, E.

    2001-01-01

    We have measured IV curves of multiwalled carbon nanotubes using end contacts. At low voltages, the tunneling conductance obeys non-Ohmic power law, which is predicted both by the Luttinger liquid and the environment-quantum-fluctuation theories. However, at higher voltages we observe a crossover to Ohm’s law with a Coulomb-blockade offset, which agrees with the environment-quantum-fluctuation theory, but cannot be explained by the Luttinger-liquid theory. From the high-voltage tunneling cond...

  6. Multiwalled Carbon nanotube - Strength to polymer composite

    Pravin, Jagdale; Khan, Aamer. A.; Massimo, Rovere; Carlo, Rosso; Alberto, Tagliaferro

    2016-02-01

    Carbon nanotubes (CNTs), a rather fascinating material, are among the pillars of nanotechnology. CNTs exhibit unique electrical, mechanical, adsorption, and thermal properties with high aspect ratio, exceptional stiffness, excellent strength, and low density, which can be exploited in the manufacturing of revolutionary smart nano composite materials. The demand for lighter and stronger polymer composite material in various applications is increasing every day. Among all the possibilities to research and exploit the exceptional properties of CNTs in polymer composites we focused on the reinforcement of epoxy resin with different types of multiwalled carbon nano tubes (MWCNTs). We studied mechanical properties such as stress, strain, ultimate tensile strength, yield point, modulus and fracture toughness, and Young's modulus by plotting and calculating by means of the off-set method. The mechanical strength of epoxy composite is increased intensely with 1 and 3 wt.% of filler.

  7. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  8. Multiwalled Carbon Nanotubes for Amperometric Array-Based Biosensors

    Taurino, Irene; De Micheli, Giovanni; Carrara, Sandro

    2012-01-01

    For diagnostic and therapeutic purposes an accurate determination of multiple metabolites is often required. Amperometric devices are attractive tools to quantify biological compounds due to the direct conversion of a biochemical event to a current. This review addresses recent developments in the use of multiwalled carbon nanotubes to enhance detection ca- pability of amperometric array-based biosensors. More specifically, the principal techniques for multiwalled carbon nanotube incorporatio...

  9. Multiwalled carbon nanotube film for strain sensing

    We have studied the possibility of using multiwalled carbon nanotube (MWCNT) films as strain sensors. The MWCNT films were prepared by a solution/filtration method and were bonded directly onto specimens by a nonconductive adhesive. For comparison, conventional foil strain gages were also bonded to the structure on the opposite side. The specimens then underwent a uniaxial tensile load-unload cycle to evaluate them as strain sensors. To ensure good electrical contact between carbon nanotube film and the wires, a thin layer of copper was thermally deposited on both ends of the film as electrodes, and the wires were connected to the electrodes by silver ink. Wheatstone bridges were used to convert the resistance changes of the MWCNTs to voltage output. Results indicated that the output voltages were proportional to the strain readings from the stain indicator. The effect of temperature on the resistance was measured and the MWCNT film resistance was found to be independent of temperature over the range 273-363 K. The optimal film dimension for strain sensing was evaluated as well. Dynamic tests suggest that the MWCNTs were able to extract the structural signature. Our results indicate that MWCNT film is potentially useful for structural health monitoring and vibration control applications

  10. Modified Multiwall Carbon Nanotubes with Nanolumps for Nanocomposite Reinforcement

    Wen, J. G.; Lao, J. Y.; Li, W. Z.; Ren, Z. F.; Department Of Physics Team

    2002-03-01

    The quality of the bonding between a polymer matrix and carbon nanotubes is critical in the development of carbon nanotube reinforced polymer composites. In this paper, we modified multiwall carbon nanotubes by growing boron carbide (a covalent bonding compound) nanolumps on carbon nanotubes to enhance load transfer from matrix to carbon nanotubes. Experimental results demonstrated that boron carbide nanolumps with the required morphology were formed on multiwall carbon nanotubes by a solid state reaction between boron and carbon nanotubes. The reaction is localized so that the integrity of the structure of carbon nanotubes is maintained. We also found that inner layers of multiwall carbon nanotubes are bonded to boron carbide nanolumps probably through covalent bonding. Therefore, these multiwall carbon nanotubes with boron carbide nanolumps are expected to be the ideal nano-scale reinforcement to improve load transfer between carbon nanotubes and the polymer matrix. For comparison, other nanolumps such as crystalline MgO, amorphous B2O3 are also grown on nanotubes.

  11. Charge transport in a single superconducting tin nanowire encapsulated in a multiwalled carbon nanotube

    Tombros, Nikolaos; Buit, Luuk; Arfaoui, Imad; Tsoufis, Theodoros; Gournis, Dimitrios; Trikalitis, Pantelis N.; van der Molen, Sense Jan; Rudolf, Petra; van Wees, Bart J.

    2008-01-01

    The charge transport properties of single superconducting tin nanowires encapsulated by multiwalled carbon nanotubes have been investigated by multiprobe measurements. The multiwalled carbon nanotube protects the tin nanowire from oxidation and shape fragmentation and therefore allows us to investig

  12. Cross-linking of multiwalled carbon nanotubes with polymeric amines

    Zhang, Youchun; Broekhuis, A. A.; Stuart, M. C. A.; Landaluce, T. F.; Fausti, D.; Rudolf, P.; Picchioni, F.

    2008-01-01

    Functionalization of carbon nanotubes is considered as an essential step to enable their manipulation and application in potential end-use products. In this paper we introduce a new approach to functionalize multiwalled carbon nanotubes (MWNTs) by applying an amidation-type grafting reaction with am

  13. 75 FR 5546 - Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes

    2010-02-03

    ... AGENCY 40 CFR Part 721 RIN 2070-AB27 Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes... chemical substance identified generically as multi-walled ] carbon nanotubes (P-08-199). This action would... commencing the manufacture, import, or processing of the specific multi-walled carbon nanotubes identified...

  14. Ag-catalysed cutting of multi-walled carbon nanotubes

    La Torre, A.; Rance, G. A.; Miners, S. A.; Herreros Lucas, C.; Smith, E. F.; Fay, M. W.; Zoberbier, T.; Giménez-López, M. C.; Kaiser, U.; Brown, P. D.; Khlobystov, A. N.

    2016-04-01

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  15. Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study

    Lunde, Anders Mathias; Flensborg, Karsten; Jauho, Antti-Pekka

    2005-01-01

    We calculate the intershell resistance R-21 in a multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F) (e.g., a gate voltage), varying the chirality of the inner and outer tubes. This is done in a so-called Coulomb drag setup, where a current I-1 in one shell induces a...

  16. Nanoelectrode ensemble based on multiwalled carbon nanotubes for electrochemical analysis

    Музика, Катерина Миколаївна; Білаш, Олена Михайлівна

    2012-01-01

    The technique of nanoelectrode ensembles development based on multiwall carbon nanotubes has been demonstrated. The obtained NEE has higher Faraday/capacitive current ratio compared to conventional electrodes of the same area, indicating a lower limit of redox-active compounds detection

  17. Investigation of electrical transport in hydrogenated multiwalled carbon nanotubes

    Highly disordered multiwalled carbon nanotubes of large outer diameter (∼60 nm) fabricated by means of chemical vapor deposition process inside porous alumina templates exhibit ferromagnetism when annealed in a H2/Ar atmosphere. In the presence of an applied magnetic field, there is a transition from positive to negative magnetoresistance. The transition may be explained in terms of the Bright model for ordered and disordered carbon structures. Additionally, temperature dependent electrical transport experiments exhibit a zero-bias anomaly at low temperature.

  18. Nonlinear Vibrations of Multiwalled Carbon Nanotubes under Various Boundary Conditions

    Hossein Aminikhah; Milad Hemmatnezhad

    2011-01-01

    The present work deals with applying the homotopy perturbation method to the problem of the nonlinear oscillations of multiwalled carbon nanotubes embedded in an elastic medium under various boundary conditions. A multiple-beam model is utilized in which the governing equations of each layer are coupled with those of its adjacent ones via the van der Waals interlayer forces. The amplitude-frequency curves for large-amplitude vibrations of single-walled, double-walled, and triple-walled carbon...

  19. Radiation modification of polyethylene nanocomposites with multiwalled carbon nanotubes

    It was studied thermomechanical properties of low density polyethylene and its nanocomposites with 1.0 and 2.0 vol.% of multiwalled carbon nanotubes treated by high energy electronic irradiation (Ee = 1.8 MeV) with doses from 0.01 to 5.0 MGy. For doses above 0.03 MGy the relative change of the length essentially differ from lower doses in the range above melting temperature of polyethylene. Therefore, within the range of 0.03...0.05 MGy of absorption dose it exists a threshold value, above which the qualitative change of thermomechanical curves behavior points out the creation of continuous network of crosslinks. The role of fillers, which were multiwalled carbon nanotubes, was studied. Nanotubes enhance the effect of electronic irradiation, leading to an increase of dimensional stability of samples. Also, they affect dependences of crystallinity degree and melting temperature on absorption dose for nanocomposites

  20. Surface Functionalization of Multiwalled Carbon Nanotube with Trifluorophenyl

    Li-Pei Zhang

    2006-09-01

    Full Text Available A new approach to dispersion of multiwalled carbon nanotube (MWNT in common polar solvents was reported. Here, a detailed study of nanotube chemistry by using trifluorophenyl (TFP to modify the surface of MWNT was discussed, which was not reported before. A characterization of the reaction products using a variety of techniques was provided. The results confirmed that the surface of MWNT was successfully functionalized. Furthermore, trifluorophenyl multiwalled carbon nanotube (TFP-MWNT was well dispersed in polar solvents, such as tetrahydrofuran (THF, acetic acid (Ac, N,N-dimethyl formamide (DMF, dimethyl sulfoxide (DMSO, due to the adsorption of trifluorophenyl groups on the surface of raw MWNT. Following chemical modification, dispersed individual nanotube suggests the potentials for wide applications.

  1. Origin of structural defects in multiwall carbon nanotube

    Hembram, K.P.S.S.; Rao, G. Mohan

    2012-01-01

    We investigate the walls of the defective multiwall carbon nanotube (MWCNT), and give possible mechanism for the formation of defective structure. A generalized model has been proposed for the MWCNT. which consists of (a) catalyst part, (b) embryo part and (c) full grown part. We claim that the weak embryo portion of the MWCNT, is structurally undeveloped. The stress due to pressure imbalance between inside and outside of the MWCNT during growth along with axial load at the embryo portion cau...

  2. Structural and surface features of multiwall carbon nanotube

    Hembram, K.P.S.S., E-mail: hembram@isu.iisc.ernet.in [Department of Instrumentation, Indian Institute of Science, Bangalore, 560012 (India); Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064 (India); Rao, G. Mohan [Department of Instrumentation, Indian Institute of Science, Bangalore, 560012 (India)

    2011-04-15

    We present the direct evidence of defective and disorder places on the surface of multiwall carbon nanotube (MWCNT), visualizing the presence of amorphous carbon at those sites. These defective surfaces being higher in energy are the key features of functionalization with different materials. The interaction of the {pi} orbital electrons of different carbon atoms of adjacent layers is more at the bent portion, than that of regular portion of the CNT. Hence the tubular structure of the bent portion of nanotubes is spaced more than that of regular portion of the nanotubes, minimizing the stress.

  3. Structural and surface features of multiwall carbon nanotube

    Hembram, K. P. S. S.; Rao, G. Mohan

    2011-04-01

    We present the direct evidence of defective and disorder places on the surface of multiwall carbon nanotube (MWCNT), visualizing the presence of amorphous carbon at those sites. These defective surfaces being higher in energy are the key features of functionalization with different materials. The interaction of the π orbital electrons of different carbon atoms of adjacent layers is more at the bent portion, than that of regular portion of the CNT. Hence the tubular structure of the bent portion of nanotubes is spaced more than that of regular portion of the nanotubes, minimizing the stress.

  4. Covalent functionalization of multi-walled carbon nanotubes by lipase

    Lipase from Candida rugosa was covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a self-catalytic mechanism. A variety of characterization techniques including FTIR, Raman spectroscopy, and XPS were employed to demonstrate the formation of the ester linkage between lipase and MWNTs. The MWNTs-lipase biocomposites showed significantly increased solubility in some common-used organic solvents, such as THF, DMF and chloroform. This study may offer a novel and facile route for covalent modification of carbon nanotubes, and expand the potential utilization of both lipases and MWNTs in the fields of biocatalyst and biosensor

  5. Determination of the intershell conductance in a multiwall carbon nanotube

    Stetter, A.; Vancea, J.; Back, C. H.

    2008-10-01

    We have measured the current induced voltage drop along an individual multiwall carbon nanotube as a function of the distance to the current injecting electrode. The measurements have been performed at room temperature using scanning probe potentiometry combined with scanning electron microscopy. For a nanotube with an incomplete outer shell, a sharp potential jump was observed at the end of the outermost shell. The electric potential variation along the carbon nanotube has been used to determine the contact resistance between metal electrodes and the tube, the intrashell resistance, and the intershell conductance.

  6. The effect of different order of purification treatments on the purity of multiwalled carbon nanotubes

    The multiwalled carbon nanotubes were purified with different order treatments of gas phase and liquid phase. Amorphous carbon and iron catalysts were removed and some oxygen-containing groups were attached to the surface of multiwalled carbon nanotubes after purification. The multiwalled carbon nanotubes were determined and characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, Boehm's neutralizing titration method and weighing method. The morphology of multiwalled carbon nanotubes was verified using scanning electron microscopy and transmission electron microscopy. The results indicated amorphous carbon and iron catalysts were removed completely while the structure of multiwalled carbon nanotubes was slightly destructed by two treatment methods. Three principal oxygen-containing groups on the surface of multiwalled carbon nanotubes were carboxyl, lactone and phenolic hydroxyl in descending order of their concentrations. The method I including gas phase treatment firstly and then liquid phase treatment, is more effective to purify multiwalled carbon nanotubes and to protect the structure of multiwalled carbon nanotubes than method II including liquid phase treatment firstly and then gas phase treatment.

  7. Physical properties of CVD boron-doped multiwalled carbon nanotubes

    Mondal, Kartick C. [Molecular Sciences Institute and School of Chemistry, University of the Witwatersrand, P.O. Wits, 2050 Johannesburg (South Africa); DST/NRF Centre of Excellence in Strong Materials, P.O. Wits, 2050 Johannesburg (South Africa); Strydom, Andre M. [Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006 (South Africa)], E-mail: amstrydom@uj.ac.za; Erasmus, Rudolph M.; Keartland, Jonathan M. [DST/NRF Centre of Excellence in Strong Materials, P.O. Wits, 2050 Johannesburg (South Africa); School of Physics, University of the Witwatersrand, P.O. Wits, 2050 Johannesburg (South Africa); Coville, Neil J. [Molecular Sciences Institute and School of Chemistry, University of the Witwatersrand, P.O. Wits, 2050 Johannesburg (South Africa); DST/NRF Centre of Excellence in Strong Materials, P.O. Wits, 2050 Johannesburg (South Africa)], E-mail: Neil.Coville@wits.ac.za

    2008-10-15

    The effects of boron doping and electron correlation on the transport properties of CVD boron-doped multiwalled carbon nanotubes are reported. The boron-doped multiwalled carbon nanotubes were characterized by TEM as well as Raman spectroscopy using different laser excitations (viz. 488, 514.5 and 647 nm). The intensity of the D-band laser excitation line increased after the boron incorporation into the carbon nanotubes. The G-band width increased on increasing the boron concentration, indicating the decrease of graphitization with increasing boron concentration. Electrical conductivity of the undoped and boron-doped carbon nanotubes reveal a 3-dimensional variable-range-hopping conductivity over a wide range of temperature, viz. from room temperature down to 2 K. The electrical conductivity is not found to be changed significantly by the present levels of B-doping. Electron Paramagnetic Resonance (EPR) results for the highest B-doped samples showed similarities with previously reported EPR literature measurements, but the low concentration sample gives a very broad ESR resonance line.

  8. Respiratory toxicity of multi-wall carbon nanotubes

    Carbon nanotubes focus the attention of many scientists because of their huge potential of industrial applications, but there is a paucity of information on the toxicological properties of this material. The aim of this experimental study was to characterize the biological reactivity of purified multi-wall carbon nanotubes in the rat lung and in vitro. Multi-wall carbon nanotubes (CNT) or ground CNT were administered intratracheally (0.5, 2 or 5 mg) to Sprague-Dawley rats and we estimated lung persistence, inflammation and fibrosis biochemically and histologically. CNT and ground CNT were still present in the lung after 60 days (80% and 40% of the lowest dose) and both induced inflammatory and fibrotic reactions. At 2 months, pulmonary lesions induced by CNT were characterized by the formation of collagen-rich granulomas protruding in the bronchial lumen, in association with alveolitis in the surrounding tissues. These lesions were caused by the accumulation of large CNT agglomerates in the airways. Ground CNT were better dispersed in the lung parenchyma and also induced inflammatory and fibrotic responses. Both CNT and ground CNT stimulated the production of TNF-α in the lung of treated animals. In vitro, ground CNT induced the overproduction of TNF-α by macrophages. These results suggest that carbon nanotubes are potentially toxic to humans and that strict industrial hygiene measures should to be taken to limit exposure during their manipulation

  9. Activity and stability studies of platinized multi-walled carbon nanotubes as fuel cell electrocatalysts

    Stamatin, Serban Nicolae; Borghei, Maryam; Dhiman, Rajnish;

    2015-01-01

    A non-covalent functionalization for multi-walled carbon nanotubes has been used as an alternative to the damaging acid treatment. Platinum nanoparticles with similar particle size distribution have been deposited on the surface modified multi-walled carbon nanotubes. The interaction between...

  10. Highly conjugated water soluble CdSe quantum dots to multiwalled carbon nanotubes

    Gui Zheng Zou

    2009-01-01

    Highly conjugated multiwalled carbon nanotube-quantum dot heterojunctions were synthesized by ethylene carbodiimide coupling procedure. The functional multiwalled carbon nanotube with carboxylic groups on sidewall could react with the amino group of L-cysteine capped CdSe quantum dots and then resulted in nanotube-quantum dot heterojunctions. Scanning electron microscopy was used to characterize the heterojunctions.

  11. Multiwalled Carbon Nanotubes Decorated with Cobalt Oxide Nanoparticles

    D. G. Larrude

    2012-01-01

    Full Text Available Multiwalled carbon nanotubes (MWCNTs synthesized by spray pyrolysis were decorated with cobalt oxide nanoparticles using a simple synthesis route. This wet chemistry method yielded nanoparticles randomly anchored to the surface of the nanotubes by decomposition of cobalt nitrate hexahydrate diluted in acetone. Electron microscopy analysis indicated that dispersed particles were formed on the MWCNTs walls. The average size increased with the increasing concentration of cobalt nitrate in acetone in the precursor mixture. TEM images indicated that nanoparticles were strongly attached to the tube walls. The Raman spectroscopy results suggested that the MWCNT structure was slightly damaged after the nanoparticle growth.

  12. Multiwalled carbon nanotube reinforced biomimetic bundled gel fibres.

    Kim, Young-Jin; Yamamoto, Seiichiro; Takahashi, Haruko; Sasaki, Naruo; Matsunaga, Yukiko T

    2016-08-19

    This work describes the fabrication and characterization of hydroxypropyl cellulose (HPC)-based biomimetic bundled gel fibres. The bundled gel fibres were reinforced with multiwalled carbon nanotubes (MWCNTs). A phase-separated aqueous solution with MWCNT and HPC was transformed into a bundled fibrous structure after being injected into a co-flow microfluidic device and applying the sheath flow. The resulting MWCNT-bundled gel fibres consist of multiple parallel microfibres. The mechanical and electrical properties of MWCNT-bundled gel fibres were improved and their potential for tissue engineering applications as a cell scaffold was demonstrated. PMID:27200527

  13. The 1/f noise in multiwalled carbon nanotubes

    Kong Wen-Jie; Lü Li; Zhang Dian-Lin; Pan Zheng-Wei

    2005-01-01

    The 1/f noise in multiwalled carbon nanotubes bundles has been investigated between the frequency range of 0.1 to 30 Hz. At room temperature the noise spectrum is standard 1/f, and its level is proportional to the square of the bias voltage. With decreasing temperature the noise level also decreases. At 4.2 K the noise level follows a non-monotonic dependence against the bias voltage, showing a peak at a certain bias voltage, meanwhile its frequency dependence also deviates from the 1/f trend. This anomalous behaviour is discussed within the picture of environmental quantum fluctuation of charge transport in the samples.

  14. Detection of methane using multi-walled carbon nanotubes

    J Kathirvelan; R Vijayaraghavan

    2015-08-01

    A sensor for detecting and estimating methane using multi-walled carbon nanotubes (MWCNTs) as the sensing element has been developed for the first time. Silver electrodes have been ink-jet printed on glass substrate over which MWCNT is brush coated to fabricate the sensor element which is of chemoresistive type. The sensitivity of the sensor (increase in the resistance of the sensor on exposure to analyte) increases linearly with concentration of methane and a maximum sensitivity of about 20% has been observed for 160 ppm of methane. A prototype device has been fabricated with this sensor and tested for its performance. It could be used to detect methane on site.

  15. Photoluminescence of multiwalled carbon nanotubes excited at different wavelengths

    Yuan Yan-Hong; Miao Run-Cai; Bai Jin-Tao; Hou Xun

    2006-01-01

    In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence (PL) spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron π in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.

  16. Van Hove singularities and nonlinear photoluminescence in multiwalled carbon nanotubes

    YUAN Yan-hong; MIAO Run-cai; LIU Bao-ying

    2006-01-01

    The absorption spectrum and photoluminescence spectrum of multiwalled carbon nanotubes(MWNTs) and the peaks related with Van Hove singularities(VHS) were obtained experimentally.Both the VHS formation and the change of band gaps in MWNTs depend on the intershell interaction.The VHS makes the probability of optical transitions enhanced,but the intershell interaction suppresses such radiative transitions.The excitation in the experiment involves a two-photon absorption process and the emission light has the effect of the optical frequency up-conversion.

  17. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers

    Matthews, Kristopher; Cruden, Brett A.; Chen, Bin; Meyyappan, M.; Delzeit, Lance

    2002-01-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  18. Novel Al-matrix nanocomposites reinforced with multi-walled carbon nanotubes

    Novel Al-based nanocomposites reinforced with multi-walled carbon nanotubes were produced by mechanical milling followed by pressure-less sintering at 823 K under vacuum. The interface between Al matrix and the multi-walled carbon nanotubes was examined using transmission electron microscopy. These observation showed that the multi-walled carbon nanotubes were not damaged during the preparation of the nanocomposite and that no reaction products were detected after sintering. The mechanical properties of sintered nanocomposites specimens were evaluated by a compression test. The yield stress (σy) and the maximum strength (σmax) obtained were considerably higher than those reported in the literature for pure Al prepared by the same route. The values for σy and σmax increase as the volume fraction of multi-walled carbon nanotubes increases. The milling time and the concentration of multi-walled carbon nanotubes have an important effect on the mechanical properties of the nanocomposite

  19. Lithium storage properties of multiwall carbon nanotubes prepared by CVD

    Full text: Multiwall carbon nanotubes (MWCNTs) were synthesised by chemical vapour deposition (CVD) method using acetylene gas. The XRD pattern of as prepared carbon nanotubes showed that the d002 value is 3.44 Angstroms. The morphology and microstructure of carbon nanotubes were characterized by HRTEM. Most of carbon nanotubes are entangled together to form bundles or ropes. The diameter of the carbon nanotubes is in the range of 10 ∼ 20 nm. There is a small amount of amorphous carbon particles presented in the sample. However, the yield of carbon nanotubes is more than 95%. Electrochemical properties of carbon nanotubes were characterised via a variety of electrochemical testing techniques. The result of CV test showed that the Li insertion potential is quite low, which is very close to O V versus Li+/Li reference electrode, whereas the potential for Li de-intercalation is in the range of 0.2-0.4 V. There exists a slight voltage hysteresis between Li intercalation and Li de-intercalation, which is similar to the other carbonaceous materials. The intensity of redox peaks of carbon nanotubes decrease with scanning cycle, indicating that the reversible Li insertion capacity gradually decreases. The carbon nanotubes electrode demonstrated a reversible lithium storage capacity of 340 mAh/g with good cyclability at moderate current density. Further improvement of Li storage capacity is possible by opening the end of carbon nanotubes to allow lithium insertion into inner graphene sheet of carbon nanotubes. The kinetic properties of lithium insertion in carbon nanotube electrodes were characterised by a.c. impedance measurements. It was found that the lithium diffusion coefficient dLi decreases with an increase of Li ion concentration in carbon nanotube host

  20. Covalent conjugation of multi-walled carbon nanotubes with proteins.

    Yi, Changqing; Qi, Suijian; Zhang, Dawei; Yang, Mengsu

    2010-01-01

    Linkage of proteins to carbon nanotubes (CNTs) is fundamentally important for applications of CNTs in medicinal and biological fields, as well as in biosensor or chemically modulated nanoelectronic devices. In this contribution, we provide a detailed protocol for the synthesis and characterization of covalent CNT-protein adducts. Functionalization of multiwalled carbon nanotubes (MWCNTs) with proteins has been achieved by the initial carboxylation of MWCNTs followed by amidation with the desired proteins. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) measurements validated the presence of a covalent linkage between MWCNTs and proteins. The visualization of proteins on the surface of MWCNTs was furthermore achieved using atomic force microscopy (AFM). The protein-conjugated nanocomposites can also be assembled into multidimensional addressable heterostructures through highly specific biomolecular recognition system (e.g., antibody-antigen). PMID:20422377

  1. Dislocation dynamics in multiwalled carbon nanotubes at high temperatures.

    Huang, J Y; Ding, F; Yakobson, B I

    2008-01-25

    Dislocation dynamics dictate the mechanical behavior of materials. Dislocations in periodic crystalline materials have been well documented. On the contrary, dislocations in cylindrical carbon nanotubes, particularly in multiwalled carbon nanotubes (MWCNTs), remain almost unexplored. Here we report that a room temperature 1/2 sessile dislocation in a MWCNT becomes highly mobile, as characterized by its glide, climb, and the glide-climb interactions, at temperatures of about 2000 degrees C. The dislocation glide leads to the cross-linking of different shells; dislocation climb creates nanocracks; and the interaction of two 1/2 dislocations creates kinks. We found that dislocation loops act as channels for mass transport. These dislocation dynamics are drastically different from that in conventional periodic crystalline materials due to the cylindrical, highly anisotropic structures of MWCNTs. PMID:18232998

  2. Multi-wall carbon nanotubes supported on carbon fiber paper synthesized by simple chemical vapor deposition

    Highlights: • We deposited multi-wall carbon nanotubes on carbon fiber paper with a simple CVD. • We investigated the inherent mechanism of Ni particle's self-dispersion. • The MWCNTs/CFP composite possesses wonderful electrical conductivity. - Abstract: Aiming at developing a novel carbon/carbon composite as an electrode in the electrochemical capacitor applications, multi-wall carbon nanotubes (MWCNTs)/carbon fiber paper (CFP) composite has been synthesized using a simple chemical vapor deposition, in which different metal catalysts such as Fe, Ni and Cu are used. However, randomly oriented MWCNTs were only obtained on Ni particles. The mechanism for this unique phenomenon is investigated in this article. The physical and electrochemical properties of as-prepared MWCNTs/CFP composite are characterized and the results show that the as-prepared composite is a promising substrate for electrochemical capacitor applications

  3. Electric current distribution of a multiwall carbon nanotube

    Chen, Li-Ying; Chen, Yu-Jyun; Chang, Chia-Seng

    2016-07-01

    The electric current distribution in a multiwall carbon nanotube (MWCNT) was studied by in situ measuring the electric potential along an individual MWCNT in the ultra-high vacuum transmission electron microscope (TEM). The current induced voltage drop along each section of a side-bonded MWCNT was measured by a potentiometric probe in TEM. We have quantitatively derived that the current on the outermost shell depends on the applied current and the shell diameter. More proportion of the total electronic carriers hop into the inner shells when the applied current is increased. The larger a MWCNT's diameter is, the easier the electronic carriers can hop into the inner shells. We observed that, for an 8 nm MWCNT with 10 μA current applied, 99% of the total current was distributed on the outer two shells.

  4. Microwave conductance of aligned multiwall carbon nanotube textile sheets

    Brown, Brian L.; Bykova, Julia S.; Howard, Austin R.; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2014-12-01

    Multiwall carbon nanotube (MWNT) sheets are a class of nanomaterial-based multifunctional textile with potentially useful microwave properties. To understand better the microwave electrodynamics, complex AC conductance measurements from 0.01 to 50 GHz were made on sheets of highly aligned MWNTs with the alignment texture both parallel and perpendicular to the microwave electric field polarization. In both orientations, the AC conductance is modeled to first order by a parallel frequency-independent conductance and capacitance with no inductive contribution. This is consistent with low-frequency diffusive Drude AC conduction up to 50 GHz, in contrast to the "universal disorder" AC conduction reported in many types of single-wall nanotube materials.

  5. Dispersion of multiwalled carbon nanotubes in aluminum powders

    DENG Chunfeng; ZHANG Peng; MA Yanxia; ZHANG Xuexi; WANG Dezun

    2009-01-01

    Multiwalled carbon nanotubes (MWNTs) were treated with the reflux within the concentrated nitric acid for 0-25 h to purify and disperse the tangled MWNTs. The effect of reflux time on the morphology and the weight loss of MWNTs were investigated. Meanwhile, the dispersion of MWNTs with 0-2.0 wt.% in 2024AI powders using mechanical stirring with an assisting ultrasonic shaker in ethanol was also studied. The results show that the reflux time markedly affects the morphology of MWNTs. The weight loss of MWNTs increases as the reflux time in-creases. When the content of MWNTs is less than 1.0 wt.%, MWNTs can uniformly distribute on the surface of 2024Al powders;however, when the content of MWNTs is 2.0 wt.%, MWNTs entangle with each other on the surface of 2024Al powders.

  6. Freestanding Aligned Multi-walled Carbon Nanotubes for Supercapacitor Devices

    Moreira, João Vitor Silva; Corat, Evaldo José; May, Paul William; Cardoso, Lays Dias Ribeiro; Lelis, Pedro Almeida; Zanin, Hudson

    2016-08-01

    We report on the synthesis and electrochemical properties of multi-walled carbon nanotubes (MWCNTs) for supercapacitor devices. Freestanding vertically-aligned MWCNTs and MWCNT powder were grown concomitantly in a one-step chemical vapour deposition process. Samples were characterized by scanning and transmission electron microscopies and Fourier transform infrared and Raman spectroscopies. At similar film thicknesses and surface areas, the freestanding MWCNT electrodes showed higher electrochemical capacitance and gravimetric specific energy and power than the randomly-packed nanoparticle-based electrodes. This suggests that more ordered electrode film architectures facilitate faster electron and ion transport during the charge-discharge processes. Energy storage and supply or supercapacitor devices made from these materials could bridge the gap between rechargeable batteries and conventional high-power electrostatic capacitors.

  7. Thermal and electrical transport in multi-walled carbon nanotubes

    Thermal and electrical transport properties of multi-walled carbon nanotubes (MWNTs), which were prepared by microwave plasma chemical vapor deposition technique, were investigated using pulsed photothermal reflectance and the two-terminal I-V methods. The effective thermal conductivity in the nanotube axis direction was around 200 W/mK at room temperature, and it was independent on the nanotube length. By comparing the thermal conductivity with the electrical conductivity, heat transport was found to be dominated by phonons instead of electrons. On the other hand, the electrical conductivity of the MWNT films exhibited anisotropic characteristics with respect to the nanotube axis and the electron transport was diffusive rather than ballistic

  8. Adsorption of uranium with multiwall carbon nanotubes modified by formaldehyde

    Purified multiwall carbon nanotubes (MWCNTs) were modified with formaldehyde and the dispersibility of MWCNTs was greatly improved after modification. The modified MWCNTs were used to study the adsorption of uranium from aqueous solution. pH, contact time, temperature, initial concentration of uranium and modified MWCNTs concentrations were investigated to estimate the adsorptive properties. The results show that uranium adsorption percentage strongly depends on the pH, initial concentration of uranium and modified MWCNTs content, and is slightly influenced by contact time, temperature and ionic strength. The adsorptivity increases over the range of pH=2.0-7.0. The maximum adsorptivity is 46.44 mg/g as the initial concentration of uranium reaches 50 μg/mL. The equilibrium data obey both Langmuir and Freundlich isotherms well, and the maximal theoretical adsorption capacity is 55.87 mg/g for the modified MWCNTs. (authors)

  9. Electrical measurement on individual multi-walled carbon nanotubes

    ZOU Xiao-ping; H. ABE; T. SHIMIZU; A. ANDO; H. OKUMOTO; ZHU Shen-ming; ZHOU Hao-shen

    2006-01-01

    The characterization of electrical property of multi-walled carbon nanotubes (MWCNTs) on a nanometer scale is essential for their potential application in nano-electronic devices. The MWCNTs were synthesized on Fe2O3/SiO2/Si substrate and Pt plate substrate by simple thermal chemical vapor deposition (STCVD) technique and the electrical measurements of individual MWCNT grown on silicon substrate and Pt plate substrate were performed by home-made 'nano-manipulator',respectively. According to current-voltage curves obtained in the experiments the current density that the MWCNTs can carry is calculated to be about 107 A/cm2,which is much larger than that of normal metals.

  10. Thermal Stability of Zirconia-coated Multiwalled Carbon Nanotubes

    R. Manivannan

    2010-04-01

    Full Text Available Sol-gel method has been used to coat multiwalled carbon nanotubes (MWCNTs with zirconia at room temperature and the coated tubes were sintered at high temperature. The samples were characterised by Raman spectroscopy, x-ray diffraction, environmental scanning electron microscope, transmission electron microscopy, and energy-dispersive x-ray analyses. The performance of the coated-MWCNTs was investigated as a function of temperature. The TGA studies indicated that sintering of coated-MWCNTs has improved its oxidation resistance and this improvement is related to the proper selection of sintering temperature.Defence Science Journal, 2010, 60(3, pp.337-342, DOI:http://dx.doi.org/10.14429/dsj.60.362

  11. Multiwalled Carbon Nanotubes Inhibit Tumor Progression in a Mouse Model.

    García-Hevia, Lorena; Villegas, Juan C; Fernández, Fidel; Casafont, Íñigo; González, Jesús; Valiente, Rafael; Fanarraga, Mónica L

    2016-05-01

    Understanding the molecular mechanisms underlying the biosynthetic interactions between particular nanomaterials with specific cells or proteins opens new alternatives in nanomedicine and nanotoxicology. Multiwalled carbon nanotubes (MWCNTs) have long been explored as drug delivery systems and nanomedicines against cancer. There are high expectations for their use in therapy and diagnosis. These filaments can translocate inside cultured cells and intermingle with the protein nanofilaments of the cytoskeleton, interfering with the biomechanics of cell division mimicking the effect of traditional microtubule-binding anti-cancer drugs such as paclitaxel. Here, it is shown how MWCNTs can trigger significant anti-tumoral effects in vivo, in solid malignant melanomas produced by allograft transplantation. Interestingly, the MWCNT anti-tumoral effects are maintained even in solid melanomas generated from paclitaxel-resistant cells. These findings provide great expectation in the development of groundbreaking adjuvant synthetic microtubule-stabilizing chemotherapies to overcome drug resistance in cancer. PMID:26866927

  12. Multi-walled carbon nanotube arrays for gas sensing applications

    Vertically aligned multi-walled carbon nanotube (MWCNT) arrays fabricated by xylene pyrolysis in anodized aluminum oxide (AAO) templates without the use of a catalyst were integrated into a resistive sensor design. Steady state sensitivities as high as 5% and 10% for 100 ppm of NH3 and NO2, respectively, at a flow rate of 750 sccm were observed. A thin layer of amorphous carbon (5-50 nm), formed on both sides of the template during xylene pyrolysis, was part of the sensor design. The thickness of the conducting amorphous carbon layers was found to play a crucial role in determining the sensitivity of the resistive sensor. A study was undertaken to elucidate (i) the dependence of sensitivity on the thickness of amorphous carbon layers, (ii) the effect of UV light on gas desorption characteristics and (iii) the dependence of room temperature sensitivity on different NH3 flow rates. Variations in sensor resistance with exposure to oxidizing and reducing gases are explained on the basis of charge transfer between the analytes and the CNTs which were modeled as p-type semiconductors

  13. Exchange of Surfactant by Natural Organic Matter on the Surfaces of Multi-Walled Carbon Nanotubes

    The increasing production and applications of multi-walled carbon nanotubes (MWCNTs) have elicited concerns regarding their release and potential adverse effects in the environment. To form stable aqueous MWCNTs suspensions, surfactants are often employed to facilitate dispersion...

  14. Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response

    To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT...

  15. Synthesis of multiwalled carbon nanotube from different grades of carbon black using arc discharge method

    Arora, Neha; Sharma, N. N.

    2016-04-01

    This paper describes the synthesis of nanotube from different grades (Tread * A(non-ASTM), N134,N121,N660 and N330)of carbon black using DC arc discharge method at 40A current for 60sec. Carbon black samples of different grades were procured from industry (Aditya Birla Science and Technology Limited, India). Scanning Electron Micrographs (SEM) of the deposited carbon nanostructures suggests that MWCNTs are formed at 40A and for a minimal exposure time of 60sec.The result formed indicates the N330 grade of carbon black gets converted to MWCNTs (Multiwall Carbon nanotube) as compared to other grades.

  16. Multi-wall carbon nanotubes with nitrogen-containing carbon coating

    Tomšík, Elena; Morávková, Zuzana; Stejskal, Jaroslav; Trchová, Miroslava; Šálek, Petr; Kovářová, Jana; Zemek, Josef; Cieslar, M.; Prokeš, J.

    2013-01-01

    Roč. 67, č. 8 (2013), s. 1054-1065. ISSN 0366-6352 R&D Projects: GA ČR GPP108/11/P763; GA ČR GAP205/12/0911; GA ČR GA202/09/0428 Institutional support: RVO:61389013 ; RVO:68378271 Keywords : polyaniline coating * carbonization * multi-wall carbon nanotubes Subject RIV: CD - Macromolecular Chemistry; BM - Solid Matter Physics ; Magnetism (FZU-D) Impact factor: 1.193, year: 2013

  17. Electromagnetic properties of texture composite materials based on hexagonal ferrites/multiwalled carbon nanotubes

    Dotsenko, O. A.; Frolov, K. O.; Wagner, D. V.

    2016-02-01

    In this article, the frequency dependence of the absorption coefficient and electromagnetic losses of the composite based on ferrite powder and / or multi-walled carbon nanotubes are presented. The dielectric and magnetic losses in the composite were measured in the range of 0.01 - 20 GHz. It has been found to increase the absorption of electromagnetic radiation and increased losses in the samples containing multi-walled carbon nanotubes.

  18. Effects of oxygen on multiwall carbon nanotubes growth by PECVD

    Chun-mei ZHANG; Ya-bo FU; Qiang CHEN; Yue-fei ZHANG

    2008-01-01

    Multiwall carbon nanotubes (MWCNTs) were grown by dielectric barrier discharge (DBD)-type plasma enhanced chemical vapor deposition (PECVD) method in downstream. The temperature was 973 K and the com-positions of gases were methane, hydrogen and oxygen in the total pressure of 0.05 MPa. The effect of O2 concen-tration in the mixture on the configuration of carbon nanotubes (CNTs) was investigated in detail. Results from scanning electron microscope (SEM) and transmis-sion electron microscope (TEM) showed that CNTs grown in CH4/H2 (38.6%/61.4%, volume) mixture have many defects and contained disordered graphitic materials. With the addition of appropriate amount of O2 (~0.67%), high-purity CNTs could be obtained. However, no CNT, even no carbon matrix existed under the condition of an excessive oxygen concentration (> 1.0%, volume) in the mixture. In order to understand the role of O2 during CNTs growth, optical emission spectroscopy (OES) was in-situ employed and the results predicted that the improve-ment of CNTs quality in O2 addition was attributed to the effect of OH oxidation from the reaction of atomic oxygen with hydrogen in the plasma.

  19. Radio frequency plasma mediated dry functionalization of multiwall carbon nanotube

    Nair, Leena G.; Mahapatra, Anirban S. [Department of Chemistry, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India); Gomathi, N., E-mail: gomathi@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India); Joseph, K. [Department of Chemistry, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India); Neogi, S. [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721301 (India); Nair, C.P. Reghunadan [Polymers and Special Chemicals Group, Vikram Sarabhai Space Centre, Trivandrum, Kerala 695022 (India)

    2015-06-15

    Highlights: • Plasma functionalization of MWCNT to obtain oxygen and nitrogen containing groups. • Functionalization and removal of amorphous carbon from MWCNT without affecting structural integrity. • Enhanced dispersion in water. • Plasma-CNT interaction mechanism. - Abstract: Surface modification of multiwall carbon nanotubes (MWCNT) was carried out by radio frequency (RF) plasma discharges of oxygen and nitrogen gases to improve their dispersibility. Various oxygen and nitrogen containing functional groups were incorporated as a result of plasma treatment and were confirmed through Fourier transform infrared spectroscopy (FTIR). The effect of plasma treatment on structural properties and morphology changes of MWCNTs was analyzed by Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The morphological studies indicate that untreated MWCNT exists as closely packed with highly entangled bundle. During the plasma treatment, MWCNT tubes get disentangled. XRD, Raman and TEM confirmed the absence of any surface damage during plasma treatment. Functionalized carbon nanotubes exhibit high zeta potential values indicating their good dispersibility in water. The method offers a direct and dry means for functionalization of MWCNT without affecting the structure of MWCNT.

  20. Radio frequency plasma mediated dry functionalization of multiwall carbon nanotube

    Highlights: • Plasma functionalization of MWCNT to obtain oxygen and nitrogen containing groups. • Functionalization and removal of amorphous carbon from MWCNT without affecting structural integrity. • Enhanced dispersion in water. • Plasma-CNT interaction mechanism. - Abstract: Surface modification of multiwall carbon nanotubes (MWCNT) was carried out by radio frequency (RF) plasma discharges of oxygen and nitrogen gases to improve their dispersibility. Various oxygen and nitrogen containing functional groups were incorporated as a result of plasma treatment and were confirmed through Fourier transform infrared spectroscopy (FTIR). The effect of plasma treatment on structural properties and morphology changes of MWCNTs was analyzed by Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The morphological studies indicate that untreated MWCNT exists as closely packed with highly entangled bundle. During the plasma treatment, MWCNT tubes get disentangled. XRD, Raman and TEM confirmed the absence of any surface damage during plasma treatment. Functionalized carbon nanotubes exhibit high zeta potential values indicating their good dispersibility in water. The method offers a direct and dry means for functionalization of MWCNT without affecting the structure of MWCNT

  1. Dispersion of multi-walled carbon nanotubes in biocompatible dispersants

    Owing to their phenomenal electrical and mechanical properties, carbon nanotubes (CNT) have been an area of intense research since their discovery in 1991. Different applications for these nanoparticles have been proposed, among others, in electronics and optics but also in the medical field. In parallel, emerging studies have suggested potential toxic effects of CNT while others did not, generating some conflicting outcomes. These discrepancies could be, in part, due to different suspension approaches used and to the agglomeration state of CNT in solution. In this study, we described a standardized protocol to obtain stable CNT suspensions, using two biocompatible dispersants (Pluronic F108 and hydroxypropylcellulose) and to estimate the concentration of CNT in solution. CNT appear to be greatly individualized in these two dispersants with no detection of remaining bundles or agglomerates after sonication and centrifugation. Moreover, CNT remained perfectly dispersed when added to culture medium used for in vitro cell experiments. We also showed that Pluronic F108 is a better dispersant than hydroxypropylcellulose. In conclusion, we have developed a standardized protocol using biocompatible surfactants to obtain reproducible and stable multi-walled carbon nanotubes suspensions which can be used for in vitro or in vivo toxicological studies.

  2. Surface modification of multiwall carbon nanotubes by sulfonitric treatment

    Gómez, Sofía; Rendtorff, Nicolás M.; Aglietti, Esteban F.; Sakka, Yoshio; Suárez, Gustavo

    2016-08-01

    Carbon nanotubes are widely used for electronic, mechanical, and optical devices due to their unique structural and quantum characteristics. The species generated by oxidation on the surface of these materials permit binding new reaction chains, which improves the dispersibility, processing and compatibility with other materials. Even though different acid treatments and applications of these CNT have been reported, relatively few research studies have focused on the relationship between the acid treatment and the formation of nanodefects, specific oxidized species or CNT surface defects. In this work, multiwall carbon nanotube (MWCNT) oxidation at 90 °C was characterized in order to determine the acid treatment effect on the surface. It was found that oxidized species are already present in MWCNT without an acid treatment, but there are not enough to cause water-based dispersion. The species were identified and quantified by infrared spectroscopy and X-ray photoelectron spectroscopy. Also, transmission electron microscopy observations showed not only modifications of the oxidized species, but also morphological damage on the surfaces of MWCNT after being subjected to the acid treatment. This effect was also confirmed by Raman spectroscopy. The acid treatment generates higher oxidized species, decreasing the zeta potential in the whole pH range.

  3. CO2 Separation from Syngas by Multiwall Carbon Nanotube

    Soodabeh Khalili

    2012-01-01

    Full Text Available In this study the equilibrium uptakes of hydrogen and carbon dioxid as the main constituents of syngas by the multi-walled carbon nanotube (MWCNT were investigated at the temperature range of 288-318 K and pressure up to 40 bars. The results have shown that temperature had much less effect on the adsorption of H2 on MWCNT than adsorption of CO2. Several model isotherms such as Langmuir and Freundlich were examined to fit the equilibrium uptake data. The kinetics of H2 and CO2 adsorption on MWCNT were also investigated and the results revealed a fast sorption kinetic for both gas adsorption on MWCNT. Isosteric heat of adsorption was evaluated based on the Clausius–Clapeyron equation at different temperatures. Small values of isosteric heat of adsorption confirmed that although the adsorption of H2 and CO2 on MWCNT were exothermic, but the heat of adsorption was too low, therefore the process of adsorption of both gases on the MWCNT used in this study is physisorption.

  4. Multiwall carbon nanotube Josephson junctions with niobium contacts

    The main goal of this thesis is the investigation of dissipationless supercurrent in multiwall carbon nanotubes embedded in a controlled environment. The experimental observation of a dissipationless supercurrent in gated carbon nanotubes remains challenging because of its extreme sensitivity to the environment and to noise fluctuations. We address these issues by choosing niobium as a superconductor and by designing an optimized on chip electromagnetic environment. The environment is meant to reduce the suppression of the supercurrent and allows to disentangle the effects of thermal fluctuations from the intrinsic behavior of the junction. This is crucial for the extraction of the value critical current from the measured data. When the transparency of the contacts is high enough we observed a fully developed supercurrent and we found that it depends on the gate voltage in a resonant manner. In average the critical current increases when the gate is tuned more negative, reflecting the increase of the transparency of the contacts, while the resonant behavior is due to quantum interference effects. We measured the temperature dependence of the switching current and we analyzed the data with an extended RCSJ model that allow to extract the critical current from the experimental data. The measured critical currents are very high with respect to previous reports on gated devices. At positive gate voltage the contacts transparency is lowered and Coulomb blockade is observed. This allows to use Coulomb blockade measurements to further characterize the nanotube and to study the physics of a quantum dot coupled to superconducting leads. The last part of this thesis is dedicated to the measurements of a carbon nanotube Josephson junction in the Coulomb blockade regime. (orig.)

  5. Multiwall carbon nanotube Josephson junctions with niobium contacts

    Pallecchi, Emiliano

    2009-02-17

    The main goal of this thesis is the investigation of dissipationless supercurrent in multiwall carbon nanotubes embedded in a controlled environment. The experimental observation of a dissipationless supercurrent in gated carbon nanotubes remains challenging because of its extreme sensitivity to the environment and to noise fluctuations. We address these issues by choosing niobium as a superconductor and by designing an optimized on chip electromagnetic environment. The environment is meant to reduce the suppression of the supercurrent and allows to disentangle the effects of thermal fluctuations from the intrinsic behavior of the junction. This is crucial for the extraction of the value critical current from the measured data. When the transparency of the contacts is high enough we observed a fully developed supercurrent and we found that it depends on the gate voltage in a resonant manner. In average the critical current increases when the gate is tuned more negative, reflecting the increase of the transparency of the contacts, while the resonant behavior is due to quantum interference effects. We measured the temperature dependence of the switching current and we analyzed the data with an extended RCSJ model that allow to extract the critical current from the experimental data. The measured critical currents are very high with respect to previous reports on gated devices. At positive gate voltage the contacts transparency is lowered and Coulomb blockade is observed. This allows to use Coulomb blockade measurements to further characterize the nanotube and to study the physics of a quantum dot coupled to superconducting leads. The last part of this thesis is dedicated to the measurements of a carbon nanotube Josephson junction in the Coulomb blockade regime. (orig.)

  6. Electrically Driven Vaporization Of Multiwall Carbon Nanotubes For Rotary Bearing Creation

    Fennimore, A. M.; Yuzvinsky, T. D.; Regan, B. C.; Zettl, A.

    2004-09-01

    We have previously reported on the creation of nanoscale rotational actuators based on multiwall carbon nanotubes. During the fabrication of these devices, we torsionally sheared the outer walls of the MWCNT to form a rotational bearing. We have designed an alternate technique for forming a rotational bearing geometry using electrically driven vaporization (EDV) of multiwall nanotube shells. While applying this technique, we have discovered an interesting failure mode.

  7. Combined torsional buckling of multi-walled carbon nanotubes

    This paper reports the results of an investigation on combined torsional buckling of an individual multi-walled carbon nanotube (MWNT) under combined torque and axial loading. Here, a multiple shell model is adopted and the effect of van der Waals forces between two adjacent tubes is taken into account. According to the ratio of radius to thickness, MWNTs discussed in this paper are classified into three types: thin, thick and nearly solid. The critical shear stress and the combined buckling mode are calculated for three types of MWNTs under combined torque and axial loading. Results carried out show that the buckling mode (m, n) corresponding to the critical shear stress is unique, which is obviously different from the purely axial compression buckling of an individual MWNT. Numerical results also show that the critical shear stresses and the corresponding buckling modes of MWNTs under combined torque and axial loading are dependent on the axial loading form and the types of MWNTs. The new features and meaningful numerical results in the present work on combined buckling of MWNTs under combined torque and axial loading may be used as a useful reference for the designs of nano-drive devices and rotational actuators in which MWNTs act as basic elements

  8. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    The pristine multi-walled carbon nanotubes (MWCNTs) were oxidized by the ultrasonication process. The oxidized MWCNTs were characterized by the X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) and Fourier transform -Raman (FT-Raman) spectroscopic techniques. The XRD analysis confirms that the oxidized MWCNTs exist in a hexagonal structure and the sharp XRD peak corresponds to the (002) Bragg's reflection plane, which indicates that the MWCNTs have higher crystalline nature. The UV-Vis analysis confirms that the MWCNTs functionalized with the carboxylic acid. The red shift was observed corresponds to the D band in the Raman spectrum, which reveals that the reduced disordered graphitic structure of oxidized MWCNTs. The strong Raman peak was observed at 2563 cm-1 corresponds to the overtone of the D band, which is the characteristic vibrational mode of oxidized MWCNTs. The carboxylic acid functionalization of MWCNTs enhances the dispersibility, which paves the way for potential applications in the field of biosensors and targeted drug delivery.

  9. Electrical properties of multiwalled carbon nanotube reinforced fused silica composites.

    Xiang, Changshu; Pan, Yubai; Liu, Xuejian; Shi, Xiaomei; Sun, Xingwei; Guo, Jingkun

    2006-12-01

    Multiwalled carbon nanotube (MWCNT)-fused silica composite powders were synthesized by solgel method and dense bulk composites were successfully fabricated via hot-pressing. This composite was characterized by XRD, HRTEM, and FESEM. MWCNTs in the hot-pressed composites are in their integrity observed by HRTEM. The electrical properties of MWCNT-fused silica composites were measured and analyzed. The electrical resistivity was found to decrease with the increase in the amount of the MWCNT loading in the composite. When the volume percentage of the MWCNTs increased to 5 vol%, the electrical resistivity of the composite is 24.99 omega cm, which is a decrease of twelve orders of value over that of pure fused silica matrix. The electrical resistivity further decreases to 1.742 omega. cm as the concentration of the MWCNTs increased to 10 vol%. The dielectric properties of the composites were also measured at the frequency ranging from 12.4 to 17.8 GHz (Ku band) at room temperature. The experimental results reveal that the dielectric properties are extremely sensitive to the volume percentage of the MWCNTs, and the permittivities, especially the imaginary permittivities, increase dramatically with the increase in the concentration of the MWCNTs. The improvement of dielectric properties in high frequency region mainly originates from the greatly increasing electrical properties of the composite. PMID:17256338

  10. Common Wet Chemical Agents for Purifying Multiwalled Carbon Nanotubes

    Rasel Das

    2014-01-01

    Full Text Available Purification and functionalization of multiwalled carbon nanotubes (MWCNTs are challenging but vital for their effective applications in various fields including water purification technologies, optoelectronics, biosensors, fuel cells, and electrode arrays. The currently available purification techniques, often complicated and time consuming, yielded shortened and curled MWCNTs that are not suitable for applications in certain fields such as membrane technologies, hybrid catalysis, optoelectronics, and sensor developments. Here we described the H2O2 synergy on the actions of HCl and KOH in purifying and functionalizing pristine MWCNTs. The method (HCl/H2O2 showed 100% purification yield as compared to HCl and KOH/H2O2 with purification yields 93.46 and 3.92%, respectively. We probed the findings using transmission electron microscope, energy dispersive X-ray spectroscope, attenuated total reflectance infrared spectroscope, Raman spectroscope, thermal gravimetric analysis, and X-ray powder diffraction. The study is a new avenue for simple, rapid, low cost, and scalable purification of pristine MWCNTs for application in versatile fields.

  11. Microwave conductance properties of aligned multiwall carbon nanotube textile sheets

    Brown, Brian L.; Martinez, Patricia; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2015-07-01

    Understanding the conductance properties of multi-walled carbon nanotube (MWNT) textile sheets in the microwave regime is essential for their potential use in high-speed and high-frequency applications. To expand current knowledge, complex high-frequency conductance measurements from 0.01 to 50 GHz and across temperatures from 4.2 K to 300 K and magnetic fields up to 2 T were made on textile sheets of highly aligned MWNTs with strand alignment oriented both parallel and perpendicular to the microwave electric field polarization. Sheets were drawn from 329 and 520 μm high MWNT forests that resulted in different DC resistance anisotropy. For all samples, the microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. This is consistent with diffusive Drude conduction as the primary transport mechanism up to 50 GHz. Further, it is found that the microwave conductance is essentially independent of both temperature and magnetic field.

  12. Reinforcement of Multiwalled Carbon Nanotube in Nitrile Rubber: In Comparison with Carbon Black, Conductive Carbon Black, and Precipitated Silica

    Atip Boonbumrung; Pongdhorn Sae-oui; Chakrit Sirisinha

    2016-01-01

    The properties of nitrile rubber (NBR) reinforced by multiwalled carbon nanotube (MWCNT), conductive carbon black (CCB), carbon black (CB), and precipitated silica (PSi) were investigated via viscoelastic behavior, bound rubber content, electrical properties, cross-link density, and mechanical properties. The filler content was varied from 0 to 15 phr. MWCNT shows the greatest magnitude of reinforcement considered in terms of tensile strength, modulus, hardness, and abrasion resistance follow...

  13. Fabrication and characterization of the composites reinforced with multi-walled carbon nanotubes.

    Her, Shiuh-Chuan; Yeh, Shun-Wen

    2012-10-01

    Carbon nanotubes with superior mechanical, electrical and thermal properties have received intensive attention in recent years. In this study, multi-walled carbon nanotubes (MWCNT) were infused into a liquid epoxy, and the solution was sonicated for three hours to separate the aggregation of the MWCNTs and achieve good dispersion. The trapped air was removed from the mixture using a high vacuum. To investigate the effect of matrix stiffness on the mechanical properties of the MWCNT nanocomposites, the mixture ratio between the epoxy and hardener was varied. Two different contents (1% wt. and 2% wt.) of the multi-walled carbon nanotubes were added into the epoxy matrix. Tensile tests were conducted to determine the Young's modulus, yielding stress and tensile strength of the nanocomposites. The natural frequency and damping ratio of the nanocomposites were evaluated using free vibration tests. Experimental results show that the Young's modulus and natural frequency of MWCNT/epoxy nanocomposites increase with increase of the addition of multi-walled carbon nanotubes. While the damping ratio of the nanocomposites decreases with increase of the multi-walled carbon nanotubes. The reinforcement role of the multi-walled carbon nanotubes is less significant in a hard matrix when compares with a soft matrix. PMID:23421186

  14. Multiwalled carbon nanotube hybrids as MRI contrast agents.

    Kuźnik, Nikodem; Tomczyk, Mateusz Michał

    2016-01-01

    Magnetic resonance imaging (MRI) is one of the most commonly used tomography techniques in medical diagnosis due to the non-invasive character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required doses of these already clinically approved contrast agents. These new candidates often possess additional functionalities, e.g., the possibility of bioactivation upon action of particular stimuli, thus serving as smart molecular probes, or the coupling with therapeutic agents and therefore combining both a diagnostic and therapeutic role. Nanomaterials have been found to be an excellent scaffold for contrast agents, among which carbon nanotubes offer vast possibilities. The morphology of multiwalled carbon nanotubes (MWCNTs), their magnetic and electronic properties, the possibility of different functionalization and the potential to penetrate cell membranes result in a unique and very attractive candidate for a new MRI contrast agent. In this review we describe the different issues connected with MWCNT hybrids designed for MRI contrast agents, i.e., their synthesis and magnetic and dispersion properties, as well as both in vitro and in vivo behavior, which is important for diagnostic purposes. An introduction to MRI contrast agent theory is elaborated here in order to point to the specific expectations regarding nanomaterials. Finally, we propose a promising, general model of MWCNTs as MRI contrast agent candidates based on the studies presented here and supported by appropriate theories. PMID:27547627

  15. Multi-walled carbon nanotubes: sampling criteria and aerosol characterization

    Chen, Bean T.; Schwegler-Berry, Diane; McKinney, Walter; Stone, Samuel; Cumpston, Jared L.; Friend, Sherri; Porter, Dale W.; Castranova, Vincent; Frazer, David G.

    2015-01-01

    This study intends to develop protocols for sampling and characterizing multi-walled carbon nanotube (MWCNT) aerosols in workplaces or during inhalation studies. Manufactured dry powder containing MWCNT’s, combined with soot and metal catalysts, form complex morphologies and diverse shapes. The aerosols, examined in this study, were produced using an acoustical generator. Representative samples were collected from an exposure chamber using filters and a cascade impactor for microscopic and gravimetric analyses. Results from filters showed that a density of 0.008–0.10 particles per µm2 filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT’s, resuspended at a concentration of 10 mg/m3, contained 2.7 × 104 particles/cm3. Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9 × 105 nanotubes/cm3. In addition, fibrous particles within the aerosol had a count median length of 3.04 µm and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 µm. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 µm. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88 g/cm3, and the mean shape factor of individual nanotubes was between 1.94 and 2.71. The information obtained from this study can be used for designing animal inhalation exposure studies and adopted as guidance for sampling and characterizing MWCNT aerosols in workplaces. The measurement scheme should be relevant for any carbon nanotube aerosol. PMID:23033994

  16. A Study On Positron - Electron Annihilation In Multi-Wall Carbon Nabitan

    Positron annihilation in multi-wall carbon nanotube is studied using positron lifetime measurements and positron diffusion theory in nano material. Experimental measurements of positron lifetime were performed on multi-wall carbon nanotube samples having various average radiuses. A closed correlation between positron lifetime on tube surface and tube radius was found, which indicates that positron lifetime measurement could become a useful means for investigating average diameter of multi-wall carbon nanotubes. Furthermore, in this work the positron diffusion theory in nano material modifying from positron diffusion model in nanofilament was used for studying effects of rate of positron runaway k from a nanotube to positron annihilation characteristics. Result shows a strong influence of nanotube radius to the rate of positron runaway and positron lifetime. Beside, value of shape coefficient α for positron diffusion in multi-wall carbon nanotubes also was calculated from experimental data. A quite good agreement between experimental and calculated values of positron annihilation probability on tube surface was result of using average shape coefficient α. Results of study demonstrate that modified positron diffusion model in nanofilament can well apply for researching positron annihilation in multi-wall carbon nanotubes. (author)

  17. Self-assembly of Silver Nanoparticles and Multiwall Carbon Nanotubes on Decomposed GaAs Surfaces

    Unnikrishnan NV

    2010-01-01

    Full Text Available Abstract Atomic Force Microscopy complemented by Photoluminescence and Reflection High Energy Electron Diffraction has been used to study self-assembly of silver nanoparticles and multiwall carbon nanotubes on thermally decomposed GaAs (100 surfaces. It has been shown that the decomposition leads to the formation of arsenic plate-like structures. Multiwall carbon nanotubes spin coated on the decomposed surfaces were mostly found to occupy the depressions between the plates and formed boundaries. While direct casting of silver nanoparticles is found to induce microdroplets. Annealing at 300°C was observed to contract the microdroplets into combined structures consisting of silver spots surrounded by silver rings. Moreover, casting of colloidal suspension consists of multiwall carbon nanotubes and silver nanoparticles is observed to cause the formation of 2D compact islands. Depending on the multiwall carbon nanotubes diameter, GaAs/multiwall carbon nanotubes/silver system exhibited photoluminescence with varying strength. Such assembly provides a possible bottom up facile way of roughness controlled fabrication of plasmonic systems on GaAs surfaces.

  18. Effect of doping of multi-walled carbon nanotubes on phenolic based carbon fiber reinforced nanocomposites

    We report on the effect of multi-walled carbon nanotubes (MWCNTs) on different properties of phenolic resin. A low content of MWCNTs (∼ 0.05 wt%) was mixed in phenolic resin and a stable dispersion was achieved by ultrasonication, followed by melt mixing. After curing the characterization of these composites was done by using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infra-red spectroscopy (FTIR). The thermal and ablative properties of carbon fiber reinforced MWCNTs-phenolic nanocomposites were also studied. The addition of MWCNTs showed improvement in thermal stability and ablation properties.

  19. Synergetic Effects of Mechanical Properties on Graphene Nanoplatelet and Multiwalled Carbon Nanotube Hybrids Reinforced Epoxy/Carbon Fiber Composites

    2015-01-01

    Graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) are novel nanofillers possessing attractive characteristics, including robust compatibility with most polymers, high absolute strength, and cost effectiveness. In this study, an outstanding synergetic effect on the grapheme nanoplatelets (GNPs) and multiwalled carbon nanotubes (CNTs) hybrids were used to reinforce epoxy composite and epoxy/carbon fiber composite laminates to enhance their mechanical properties. The mechanical propertie...

  20. Functionalized multi-walled carbon nanotubes in an aldol reaction

    Chronopoulos, D. D.; Kokotos, C. G.; Karousis, N.; Kokotos, G.; Tagmatarchis, N.

    2015-01-01

    The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde was evaluated for the first time, showing to proceed almost quantitatively in aqueous media. Furthermore, several amino-modified MWCNTs were prepared and examined in the particular aldol reaction. These new hybrid materials exhibited an enhanced catalytic activity in water, contrasting with the pristine MWCNTs as well as the parent organic molecule, which failed to catalyze the reaction efficiently. Furthermore, the modified MWCNTs proved to catalyze the aldol reaction even after three repetitive cycles. Overall, a green approach for the aldol reaction is presented, where water can be employed as the solvent and modified MWCNTs can be used as catalysts, which can be successfully recovered and reused, while their catalytic activity is retained.The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction

  1. The hepatotoxicity of multi-walled carbon nanotubes in mice

    Ji, Zongfei; Zhang, Danying; Li, Ling; Shen, Xizhong; Deng, Xiaoyong; Dong, Ling; Wu, Minhong; Liu, Yuanfang

    2009-11-01

    The hepatotoxicity of two types of multi-walled carbon nanotubes (MWCNTs), acid-oxidized MWCNTs (O-MWCNTs) and Tween-80-dispersed MWCNTs (T-MWCNTs), were investigated with Kunming mice exposed to 10 and 60 mg kg-1 by intravenous injection for 15 and 60 d. Compared with the PBS group, the body-weight gain of the mice decreased and the level of total bilirubin and aspartate aminotransferase increased in the MWCNT-exposed group with a significant dose-effect relationship, while tumor necrosis factor alpha level did not show significant statistical change within 60 d. Spotty necrosis, inflammatory cell infiltration in portal region, hepatocyte mitochondria swelling and lysis were observed with a significant dose-effect relationship in the MWCNT groups. Liver damage of the T-MWCNT group was more severe than that of the O-MWCNT group according to the Roenigk classification system. Furthermore, T-MWCNTs induce slight liver oxidative damage in mice at 15 d, which was recovered at 60 d. Part of the gene expressions of mouse liver in the MWCNT groups changed compared to the PBS group, including GPCRs (G protein-coupled receptors), cholesterol biosynthesis, metabolism by cytochrome P450, natural-killer-cell-mediated cytotoxicity, TNF- α, NF-κB signaling pathway, etc. In the P450 pathway, the gene expressions of Gsta2 (down-regulated), Cyp2B19 (up-regulated) and Cyp2C50 (down-regulated) had significant changes in the MWCNT groups. These results show that a high dose of T-MWCNTs can induce hepatic toxicity in mice while O-MWCNTs seem to have less toxicity.

  2. Effects of initial stress on non-coaxial resonance of multi-wall carbon nanotubes

    This paper reports an investigation of the influence of initial stress on the flexural vibration of an individual multi-wall carbon nanotube with simply supported ends, based on a laminated elastic beam model considering the van der Waals force interaction between two adjacent nanotubes. The results obtained show that the influence of initial stress in carbon nanotubes on their natural frequency is obvious, but the influence of initial stress in carbon nanotubes on the intertube resonant frequency of multi-wall carbon nanotubes is not obvious, especially for large aspect ratios. The influence of initial stress in carbon nanotubes on their flexural vibration modes is dependent on the tension or compression forms of the initial stress. This investigation on the influences of initial stress in multi-wall carbon nanotubes on natural frequency and intertube resonant frequency may be used as a useful reference for the application and design of nano-oscillators, nano-drive devices, nano-sensors and actuators in which multi-wall carbon nanotubes act as basic elements

  3. Structural and electrical properties of functionalized multiwalled carbon nanotube/epoxy composite

    Gantayat, S.; Rout, D.; Swain, S. K.

    2016-05-01

    The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increased with increasing concentration of f-MWCNTs.

  4. Numerical simulation of polarization beam splitter with triangular lattice of multi-walled carbon nanotube arrays

    Wu, Xingxing; Yun, Maojin; Wang, Mei; Liu, Chao; Li, Kai; Qin, Xiheng; Kong, Weijin; Dong, Lifeng

    2015-12-01

    A kind of polarization beam splitter with triangular lattice of multi-walled carbon nanotube arrays is designed and simulated. In the employed structure transverse-electric (TE) light is confined in the line defect with photonic band gap effect, while transverse-magnetic (TM) light is guided through it with extremely low diffraction. The performance of the designed polarization beam splitter is evaluated by utilizing optical properties of multi-walled carbon nanotubes, finite element modeling of wave propagation and transmission through periodic arrays. Simulation results indicate that the designed polarization beam splitter has low loss and less cross talk, and thereby may have practical applications in the integrated optical field.

  5. Effect of intense laser and energetic ion irradiation on Raman modes of Multiwalled Carbon Nanotubes

    The effects of intense laser and energetic ion irradiation on Raman vibrational modes of Multiwalled Carbon Nanotubes have been investigated. The intensity ratio of D and G modes decreases with increase in laser power density and remains almost constant with decrease of laser power density. The intensity ratio of D mode to G mode for ion irradiated Multiwalled Carbon Nanotubes decreases at low fluence (4 x 1011 ions/cm2) and increases further with increase in ion fluence. The results show that ion irradiation at low fluence and laser irradiation lead to purification/ordering of the nanotubes.

  6. Synthesis and characterization of polyaniline grafted multiwalled carbon nanotube loaded Nafion-silica nanocomposite membrane.

    Ragupathy, D; Gopalan, A; Kim, Kyeong-Wung; Lee, Kwang Pill

    2011-01-01

    The preparation and characterization results of a new nanocomposite, polyaniline (PANI) grafted multiwalled carbon nanotube (MWNT) loaded Nafion-silica, (designated as Nafion-silica/MWNT-g-PANI), are reported in this paper. The preparation involves the formation of a silica network in a Nafion membrane and the subsequent loading of polyaniline-grafted multiwalled carbon nanotubes (MWNT-g-PANI) onto the Nafion-silica nanocomposite. The new nanocomposite, Nafion-silica/ MWNT-g-PANI, was characterized as to its morphology, structure and properties. The conductivity and methanol permeability of the nanocomposite membranes were evaluated. PMID:21446537

  7. Effect of Molecular Weight on the Properties of Polyethyleneglycols Doped with Multiwalled Carbon Nanotubes

    Melnyk I.A.

    2015-08-01

    Full Text Available The aim of this study is to analyze the changes in the structure, thermal properties and electrophysical behavior of polyethylene glycol doped with multiwalled carbon nanotubes. The differential scanning calorimetry and electrical conductivity methods were used to study influence of doping multiwalled carbon NTs on the properties of polyethylene glycol of different molecular weights, Mw (PEG-400, PEG-1000, PEG-10000. Dependencies of the polymers degree of crystallinity and temperature behavior of conductivity on the concentration of NTs were researched. The obtained data indicates a strong influence of the molecular weight of PEG on the spatial distribution of NTs and electrical conductivity of researched systems.

  8. Alloy hydride catalyst route for the synthesis of single-walled carbon nanotubes, multi-walled carbon nanotubes and magnetic metal-filled multi-walled carbon nanotubes

    This paper presents a novel, cost-effective and single-step technique for the synthesis of single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs) and magnetic metal-filled MWNTs using a fixed bed reaction thermal chemical vapour deposition (CVD) using alloy hydride catalyst. The single-step method involves the pyrolysis of methane at suitable temperatures over fine powders of certain Mischmetal-based AB3 alloy hydride catalysts, prepared through the hydrogen decrepitation technique. These carbon nanostructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDAX), thermo-gravimetric analysis (TGA) and Raman spectroscopy. The magnetic properties of these metal-filled MWNTs have been studied by vibrating sample magnetometry, and the results are discussed

  9. Multiwalled carbon nanotube CVD synthesis, modification, and composite applications

    Qian, Dali

    Well-aligned carbon multiwall nanotube (MWNT) arrays have been continuously synthesized by a floating catalytic chemical vapor deposition (CVD) method involving the pyrolysis of xylene-ferrocene mixtures. The CVD parameters have been studied to selectively synthesize nanotubes with required dimensions. A mixed tip-root growth model has been proposed for the floating catalytic CVD synthesis. Coarsening of the catalyst particle at the root end promoted MWNT wall coarsening (addition of new concentric graphene shells), while the smaller catalyst particle at the tip contributed to MWNT elongation. A two-step process in which ferrocene was fed for only five minutes to nucleate the DTs was developed to understand if a continuous supply of catalyst was necessary for continued growth. The results show that the ferrocene was only necessary for initial nucleation. To simplify the CVD process further, another two-step synthesis method was developed in which the ferrocene was pre-decomposed so that the nanotube nucleation could be isolated from the growth, enabling quantification of growth mechanisms and kinetics. Mass spectra and hydrocarbon analyses of the CVD reactor tail gas were performed to understand the pyrolysis chemistry. Well-aligned N-doped and Ru-doped MWNT arrays have been produced by pyrolysis of pyridine ferrocene mixtures and xylene-ferrocene-ruthenocene mixtures, respectively. Various material characterization techniques were used to measure the dopant distributions and correlate the catalyst phase with the novel nanotube structures. High-temperature annealing has been shown to be a viable means to remove both the catalyst particles and certain microstructural defects within the CVD-derived DTs. The phase transformation of catalyst during annealing has also been studied. Homogeneous distribution of MWNTs in polystyrene matrices was achieved by an ultrasonic assisted solution-evaporation method. Addition of only 1 wt % DTs to polystyrene increased the polymer

  10. Characterization of Multiwalled Carbon Nanotubes Dispersing in Water and Association with Biological Effects

    Xuelian Cheng; Jun Zhong; Jie Meng; Man Yang; Fumin Jia; Zhen Xu; Hua Kong; Haiyan Xu

    2011-01-01

    Biomedical application potentials of carbon nanotubes-based materials have been investigated intensively in recent years; however, characterization and metrology are still facing great technical challenges when the materials are intended to be used as carriers for therapeutics in aqueous solutions. Systematic characterization on the dispersing carbon nanotubes is urgently required and therefore of significance. In this paper multiwalled carbon nanotubes (MWCNTs) with different average lengths...

  11. Decoration of Silver Nanoparticles on Multiwalled Carbon Nanotubes: Antibacterial Mechanism and Ultrastructural Analysis

    Ngo Xuan Dinh; Nguyen Van Quy; Tran Quang Huy; Anh-Tuan Le

    2015-01-01

    Recently, development of carbon nanocomposites composed of carbon nanostructures and metal nanoparticles has attracted much interests because of their large potential for technological applications such as catalyst, sensor, biomedicine, and disinfection. In this work, we established a simple chemistry method to synthesize multiwalled carbon nanotubes (MWCNTs) decorated with silver nanoparticles (Ag-NPs) using a modified photochemical reaction (Tollens process). The formation and interaction o...

  12. A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites.

    Yang, Yonglai; Gupta, Mool C; Dudley, Kenneth L; Lawrence, Roland W

    2005-06-01

    Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed. PMID:16060155

  13. A Comparative Study on AC Conductivity and Dielectric Behavior of Multiwalled Carbon Nanotubes and Polyaniline Coated Multiwalled Carbon Nanotubes Filled High Density Polyethylene-Carbon Black Nanocomposites

    This paper presents an experimental investigation on AC conductivity and dielectric behavior of carbon black reinforced high density polyethylene (HDPE-CB) and HDPE-CB filled with multiwalled carbon nanotubes (MWNTs-CB-HDPE) and Polyaniline (PAni) coated MWNTs-CB-HDPE nanocomposites. The electrical properties such as dielectric constant (ε'), dissipation factor (tan δ) and AC conductivity (σac) of nanocomposites have been measured with reference to the weight fraction (0.5 and 1 wt% MWNTs), frequency (75 KHz-30 MHz), temperature (25-90 deg. C) and sea water ageing. The experimental results showed that the increased AC conductivity and dielectric constant of the nanocomposites were influenced by PAni coated MWNTs in HDPE-CB nanocomposites. The value of dielectric constant and tan δ decreased with increasing frequency. Further more, above 5 MHz the AC conductivity increases drastically whereas significant effect on tan δ was observed in less than 1 MHz.

  14. Comparative Study of Single- and Multi-Wall Carbon Nanotubes with Application in Cerebral Aneurysm

    Rodica-Mariana Ion

    2011-01-01

    Full Text Available Helping improve humanity is one of the promises of nanotech-
    nology and nanomedicine. This paper will highlight some of the research findings in the nanomedicine area by testing some single- and multi-walls carbon nanotubues in rats cerebral aneurisms.

  15. Multi-walled carbon nanotubes integrated in microcantilevers for application of tensile strain

    Dohn, Søren; Kjelstrup-Hansen, Jakob; Madsen, D.N.;

    2005-01-01

    Individual multi-walled carbon nanotubes were positioned on silicon oxide microcantilevers using nanomanipulation tools. A silicon nanowire with a diameter of 200nm is positioned across the nanotube, and serves as shadow mask during deposition of conducting electrode material, leading to a 200 ru...

  16. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De

    2006-01-01

    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  17. Connection of silicon nanocrystals (Si-nc) with multiwalled carbon nanotubes

    Švrček, Vladimír; Ersen, O.; Dintzer, T.; Pham-Huu, C.; Ledoux, M.-J.; Le Normand, F.

    2006-01-01

    Roč. 83, č. 1 (2006), s. 153-157. ISSN 0947-8396 Grant ostatní: NANOTEMP(XE) HPRN-CT-2002-00192 Institutional research plan: CEZ:AV0Z10100521 Keywords : silicon nanocrystals * multi-walled carbon nanotubes * wiring Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.739, year: 2006

  18. Thermal stability of catalytically grown multi-walled carbon nanotubes observed in transmission electron microscopy

    Wang, Cheng-Yu; Liu, Chuan-Pu; Boothroyd, Chris

    2009-01-01

    The thermal stability of multi-walled carbon nanotubes (MWCNTs) was assessed in situ by transmission electron microscopy. Upon heating, Ni catalysts in MWC-NTs containing bamboo structures shrank from the tail due to evaporation, leading to additional bamboo formation and tube elongation at 800...

  19. A Multi-Walled Carbon Nanotube-based Biosensor for Monitoring Microcystin-LR in Sources of Drinking Water Supplies

    A multi-walled carbon nanotube-based electrochemical biosensor is developed for monitoring microcystin-LR (MC-LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using dense, mm-long multi-walled CNT (MWCNT) arrays gro...

  20. Mechanical buckling of multi-walled carbon nanotubes: The effects of slenderness ratio

    Lu, Jian-Ming; Hwang, Chi-Chuang; Kuo, Qu-Yuan; Wang, Yun-Che

    2008-03-01

    Buckling strengths, in terms of compressive strain, of single-, double- and triple-walled carbon nanotubes (CNTs) are investigated to study the effects of slenderness ratio ( SR) via the molecular dynamics (MD) simulations with the Tersoff potential. Under constant ratio of slenderness, the CNTs with small SR behave like a continuum shell object. For large SR's, multi-walled CNTs exhibit the characteristics of the Euler columns. In addition, smaller nanotubes possess higher buckling-resistance. The buckling strength of multi-walled nanotubes is controlled by the size of their outermost shell.

  1. Electrooxidation of DNA at glassy carbon electrodes modified with multiwall carbon nanotubes dispersed in polyethylenimine

    This work reports the electrochemical response of the complex between dsDNA and PEI formed in solution and at the surface of glassy carbon electrodes (GCE) modified with a dispersion of multi-walled carbon nanotubes in polyethylenimine (CNT-PEI). Scanning Electron Microscopy and Scanning Electrochemical Microscopy demonstrate that the dispersion covers the whole surface of the electrode although there are areas with higher density of CNT and, consequently, with higher electrochemical reactivity. The adsorption of DNA at GCE/CNT-PEI is fast and it is mainly driven by electrostatic forces. A clear oxidation signal is obtained either for dsDNA or a heterooligonucleotide of 21 bases (oligoY) at potentials smaller than those for the oxidation at bare GCE. The comparison of the behavior of DNA before and after thermal treatment demonstrated that the electrochemical response highly depends on the 3D structure of the nucleic acid.

  2. Biosensor based on a glassy carbon electrode modified with tyrosinase immobilized on multiwalled carbon nanotubes

    We describe a biosensor for phenolic compounds that is based on a glassy carbon electrode modified with tyrosinase immobilized on multiwalled carbon nanotubes (MWNTs). The MWNTs possess excellent inherent electrical conductivity which enhances the electron transfer rate and results in good electrochemical catalytic activity towards the reduction of benzoquinone produced by enzymatic reaction. The biosensor was characterized by cyclic voltammetry, and the experimental conditions were optimized. The cathodic current is linearly related to the concentration of the phenols between 0.4 μM and 10 μM, and the detection limit is 0.2 μM. The method was applied to the determination of phenol in water samples (author)

  3. Template directed formation of nanoparticle decorated multi-walled carbon nanotube bundles with uniform diameter

    Bundles of multi-walled carbon nanotubes of uniform diameter decorated with Ni nanoparticles were synthesized using mesoporous silicates as templates. The ordered morphology and the narrow pore size distribution of mesoporous silicates provide an ideal platform to synthesize uniformly sized carbon nanotubes. In addition, homogeneous sub-10 nm pore sizes of the templates allow in situ formation of catalytic nanoparticles with uniform diameters which end up decorating the carbon nanotubes. The resulting carbon nanotubes are multi-walled with a uniform diameter corresponding to the pore diameter of the template used during the synthesis that are decorated with the catalysts used to synthesize them. They have a narrow size distribution which can be used in many energy related fields of research.

  4. Noncovalent Attachment of PbS Quantum Dots to Single- and Multiwalled Carbon Nanotubes

    Anirban Das

    2014-01-01

    Full Text Available Attachment of PbS quantum dots (QD to single-walled carbon nanotubes (SWNT and multiwalled carbon nanotubes (MWCNT is described; wherein commercially obtained PbS-QD of size 2.7 nm, stabilized by oleic acid, are added to a suspension of single- or multiwalled carbon nanotubes (CNT prefunctionalized noncovalently with 1,2-benzenedimethanethiol (1,2-BDMT in ethanol. The aromatic part of 1,2-BDMT attaches to the CNT by π-π stacking interactions, noncovalently functionalizing the CNT. The thiol part of the 1,2-BDMT on the functionalized CNT replaces oleic acid on the surface of the QD facilitating the noncovalent attachment of the QD to the CNT. The composites were characterized by TEM and FTIR spectroscopy. Quenching of NIR fluorescence of the PbS-QD on attachment to the carbon nanotubes (CNT was observed, indicating FRET from the QD to the CNT.

  5. Effects of Multi-Walled Carbon Nanotubes on The Mechanical Properties of Glass/Polyester Composites

    M. Mehrdad Shokrieh; A Saeedi; M. Chitsazzadeh

    2012-01-01

    Excellent mechanical properties of carbon nanotubes (CNTs) make them outstanding candidate reinforcements to enhance mechanical properties of conventional composites. The glass/polyester composites are widely used in many industries and applications. Improving the mechanical properties of such composites with addition of CNTs can increase their applications. In this research, multi-walled carbon nanotube (MWCNT) at different weight ratios (0.05, 0.1, 0.3, 0.5 wt.%) were added to chopped stran...

  6. Electrochemical Reduction of Oxygen on Multi-walled Carbon Nanotubes Electrode in Alkaline Solution

    You Qun CHU; Chun An MA; Feng Ming ZHAO; Hui HUANG

    2004-01-01

    The multi-walled carbon nanotubes (MWNTs) electrode was constructed using poly- tetrafluoroethylene as binder, and the electrochemical reductive behavior of oxygen in alkaline solution was first examined on this electrode. Compared with other carbon materials, MWNTs show higher electrocatalytic activity, and the reversibility of O2 reduction reaction is greatly improved. The experiments reveal that the electrochemical reduction of O2 to HO2- is controlled by adsorption. The preliminary results illustrate the potential application of MWNTs in fuel cells.

  7. Multiwalled carbon nanotubes enter broccoli cells enhancing growth and water uptake of plants exposed to salinity

    Martínez-Ballesta, Mª Carmen; Zapata, Lavinia; Chalbi, Najla; Carvajal, Micaela

    2016-01-01

    Background Carbon nanotubes have been shown to improve the germination and growth of some plant species, extending the applicability of the emerging nano-biotechnology field to crop science. Results In this work, exploitation of commercial multiwalled carbon nanotubes (MWCNTs) in control and 100 mM NaCl-treated broccoli was performed. Transmission electron microscopy demonstrated that MWCNTs can enter the cells in adult plants with higher accumulation under salt stress. Positive effect of MWC...

  8. Comparison of different methods for characterizing multi-walled carbon nanotubes

    Gommes, Cédric; Blacher, Silvia; Dupont-Pavlovsky, N.; Bossuot, Christophe; Lamy, Michael; Brasseur, Alain; Marguillier, David; Fonseca, Antonio; McRae, E.; Nagy, J. B.; Pirard, Jean-Paul

    2004-01-01

    Four complementary and independent methods are used to characterize nanotube samples: (i) TEM observation coupled with image analysis, (ii) nitrogen and krypton adsorption isotherm analysis, (iii) thermogravimetry and (iv) wide angle X-ray scattering. The methodology is discussed on the basis of two multi-walled carbon nanotube samples produced by the CCVD technique with very different reaction rates. It is shown that the total amount of deposited carbon is larger for the sample produced at t...

  9. Frictional and wear properties of cobalt/multiwalled carbon nanotube composite films formed by electrodeposition

    Arai, Susumu; Miyagawa, Kazuaki

    2013-01-01

    Carbon nanotubes (CNTs) have solid lubricity due to their unique structure, and as such, CNT composites are also expected to exhibit superior tribological properties. In this study, Co/CNT composite films were fabricated using a composite electrodeposition technique, and their tribological properties were investigated. Three different sizes of multiwalled carbon nanotubes (MWCNTs) were used as the CNTs in this study. The microstructures of the composite films were examined using scanning elec...

  10. Development of Prototype Laboratory Setup for Selective Detection of Ethylene Based on Multiwalled Carbon Nanotubes

    2014-01-01

    We report here a prototype laboratory setup for detecting ethylene (C2H4) in ppm level employing a sensor made of multiwalled carbon nanotubes of 40 nm average tube diameter. The proposed reversible chemoresistive ethylene sensor is fabricated using Kapton as the substrate onto which carbon nanotubes are coated using thick film technology. IDT silver electrodes are printed using piezo head based ink-jet printing technology. The increases in electrical resistance of the sensor element are meas...

  11. Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

    Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

  12. Nanoscale zirconia as a nonmetallic catalyst for graphitization of carbon and growth of single- and multiwall carbon nanotubes.

    Steiner, Stephen A; Baumann, Theodore F; Bayer, Bernhard C; Blume, Raoul; Worsley, Marcus A; MoberlyChan, Warren J; Shaw, Elisabeth L; Schlögl, Robert; Hart, A John; Hofmann, Stephan; Wardle, Brian L

    2009-09-01

    We report that nanoparticulate zirconia (ZrO(2)) catalyzes both growth of single-wall and multiwall carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) and graphitization of solid amorphous carbon. We observe that silica-, silicon nitride-, and alumina-supported zirconia on silicon nucleates single- and multiwall carbon nanotubes upon exposure to hydrocarbons at moderate temperatures (750 degrees C). High-pressure, time-resolved X-ray photoelectron spectroscopy (XPS) of these substrates during carbon nanotube nucleation and growth shows that the zirconia catalyst neither reduces to a metal nor forms a carbide. Point-localized energy-dispersive X-ray spectroscopy (EDAX) using scanning transmission electron microscopy (STEM) confirms catalyst nanoparticles attached to CNTs are zirconia. We also observe that carbon aerogels prepared through pyrolysis of a Zr(IV)-containing resorcinol-formaldehyde polymer aerogel precursor at 800 degrees C contain fullerenic cage structures absent in undoped carbon aerogels. Zirconia nanoparticles embedded in these carbon aerogels are further observed to act as nucleation sites for multiwall carbon nanotube growth upon exposure to hydrocarbons at CVD growth temperatures. Our study unambiguously demonstrates that a nonmetallic catalyst can catalyze CNT growth by thermal CVD while remaining in an oxidized state and provides new insight into the interactions between nanoparticulate metal oxides and carbon at elevated temperatures. PMID:19663436

  13. Deformation and Failure of a Multi-Wall Carbon Nanotube Yarn Composite

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2008-01-01

    Forests of multi-walled carbon nanotubes can be twisted and manipulated into continuous fibers or yarns that exhibit many of the characteristics of traditional textiles. Macro-scale analysis and test may provide strength and stiffness predictions for a composite composed of a polymer matrix and low-volume fraction yarns. However, due to the nano-scale of the carbon nanotubes, it is desirable to use atomistic calculations to consider tube-tube interactions and the influence of simulated twist on the effective friction coefficient. This paper reports laboratory test data on the mechanical response of a multi-walled, carbon nanotube yarn/polymer composite from both dynamic and quasi-static tensile tests. Macroscale and nano-scale analysis methods are explored and used to define some of the key structure-property relationships. The measured influence of hot-wet aging on the tensile properties is also reported.

  14. Enhanced rate performance of multiwalled carbon nanotube encrusted olivine type composite cathode material using polyol technique

    Muruganantham, R.; Sivakumar, M.; Subadevi, R.

    2015-12-01

    Olivine type multi-walled carbon nanotube encrusted LiFePO4/C composites have been prepared using economic and energy efficient simple polyol technique without any subsequent heat treatment. The prepared material has an olivine type orthorhombic phase. Also, the iron oxidation state is 2+, which is identified by X-ray diffraction and X-ray photoelectron spectroscopy. It is possible to attain the discharge capacity almost close to theoretical capacity of LiFePO4 as in high temperature methods with ∼100% coulombic efficiency. The specific surface area has been increased upon encrusting multi walled carbon nano tube on LiFePO4/C, which results in enhanced reversible capacity upto 166 mAh g-1 at C/10. Also, it exhibits 89 mAh g-1 even at 30 C rate. This is due to the formation of conductive networks by carbon nanotube, and excellent attachment of LiFePO4/C composite particles on multi-walled carbon nanotube, which induced the kinetics during intercalation/deintercalation process. Multi-walled carbon nanotube acts as the electro-conductive filler on the LiFePO4 surface. The direct addition of MWCNT would result better performances than blending the MWCNT with LiFePO4/C.

  15. Multiwalled Carbon Nanotube Forest Grown via Chemical Vapor Deposition from Iron Catalyst Nanoparticles, by XPS

    Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

    2013-09-25

    Carbon nanotubes (CNTs) have unique chemical and physical properties. Herein, we report an XPS analysis of a forest of multiwalled CNTs using monochromatic Al Kα radiation. Survey scans show only one element: carbon. The carbon 1s peak is centered 284.5 eV. The C 1s envelope also shows the expected π → π* shake-up peak at ca. 291 eV. The valence band and carbon KVV Auger signals are presented. When patterned, the CNT forests can be used as a template for subsequent deposition of metal oxides to make thin layer chromatography plates.1-3

  16. Production of High Purity Multi-Walled Carbon Nanotubes from Catalytic Decomposition of Methane

    Kong Bee Hong; Aidawati Azlin Binti Ismail; Mohamed Ezzaham Bin Mohd Mahayuddin; Abdul Rahman Mohamed; Sharif Hussein Sharif Zein

    2006-01-01

    Acid-based purification process of multi-walled carbon nanotubes (MWNTs) produced via catalytic decomposition of methane with NiO/TiO2 as a catalyst is described. By combining the oxidation in air and the acid refluxes, the impurities, such as amorphous carbon, carbon nanoparticles, and the NiO/TiO2 catalyst, are eliminated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm the removal of the impurities. The percentage of the carbon nanotubes purity was analyzed using thermal gravimetric analysis (TGA). Using this process, 99.9 wt% purity of MWNTs was obtained.

  17. The effects of functionalized multi-walled carbon nanotube on mechanical properties of multi-walled carbon nanotube/epoxy composites

    Mehdi Ardjmand

    2015-12-01

    Full Text Available The mechanical properties of the multi-walled carbon nanotube (MWCNT/epoxy composites affected by carboxyl and amino functionalized MWCNT are investigated. Tensile tests of the specimens were carried out to obtain mechanical properties of MWCNT/epoxy composites for various weight-percents (wt % of MWCNTs. In order to properly predict the mechanical properties of MWCNT reinforced epoxy composites, the effect of MWCNTs de bonding is considered through applying a correction factor to a Halpin-Tsai equation. Applicability of the modified model was endorsed by the experimental results.

  18. Multi-walled carbon nanotubes as catalyst promoter for dimethyl ether synthesis from CO2 hydrogenation

    The mixed acid of H2SO4/HNO3-pretreated multi-walled carbon nanotubes was employed as supports and ultrasound-assisted co-precipitation method was designed to prepare multi-walled carbon nanotubes supported CuO–ZnO–Al2O3/HZSM-5 catalyst. The catalyst was characterized by means of X-ray diffraction spectrum (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermal analysis (TG) and Brunauer–Emmett–Teller (BET). The catalyst activity for the preparation of dimethyl ether from hydrogenation of CO2 was investigated in a fixed-bed reactor, which showed that multi-walled carbon nanotubes could promote the catalyst activity of CuO–ZnO–Al2O3/HZSM-5. Under the reaction conditions of temperature at 262 °C, pressure at 3.0 MPa, H2/CO2 = 3 (volume ratio) and space velocity (SV) = 1800 mL gcat−1 h−1, the conversion per pass of carbon dioxide was 46.2%, with the dimethyl ether yield and selectivity of 20.9% and 45.2%.

  19. Immobilization of Bovine Serum Albumin Upon Multiwall Carbon Nanotube for High Speed Humidity Sensing Application.

    Bhattacharya, Sankhya; Sasmal, Milan

    2016-01-01

    We present a high-speed humidity sensor based on immobilization of bovine serum albumin upon multiwall carbon nanotube (IBC). A simple and versatile drop casting technique was employed to make the humidity sensor using novel material IBC at room temperature. IBC was synthesized using easy solution process technique. The working principle of the IBC humidity sensor depends upon the variation of output current or conductance with the exposure of different humidity level. Humidity sensing properties of our device is explained on the basis of charge transfer from water molecules to IBC and bovine serum albumin to multiwall carbon nanotube (MWCNT). Our sensor exhibits faster response time around 1.2 s and recovery time 1.5 s respectively. PMID:26841403

  20. Carboxyl multiwalled carbon nanotubes modified polypyrrole (PPy) aerogel for enhanced electromagnetic absorption

    Zhang, Kun; Xie, Aming; Wu, Fan; Jiang, Wanchun; Wang, Mingyang; Dong, Wei

    2016-05-01

    Polypyrrole (PPy) aerogel is a low-cost and lightweight material with high-performance electromagnetic absorption (EA). However, it does not always meet the requirements of practical applications. In this study, we used trace amounts of carboxyl multiwalled carbon nanotubes to regulate the dielectric property of PPy aerogel, thus enhancing the EA performance. Furthermore, the reason for enhanced EA performance can be elaborated by an electron blocking mechanism.

  1. CATALYTIC WET AIR OXIDATION OF INDUSTRIAL EFFLUENTS USING A Pt CATALIST SUPPORTED ON MULTIWALLED CARBON NANOTUBES

    Gabriel Ovejero; José L. Sotelo; Araceli Rodríguez; Ana Vallet; Juan García

    2011-01-01

    In this work, catalytic wet air oxidation in a batch reactor was studied by catalytic wet air oxidation to treat industrial wastewater. Basic Yellow 11, a basic dye, was employed as a model compound and platinum supported over multi-walled nanotubes (Pt/MWNT) was used as catalyst. Additionally, two different industrial wastewaters were tested. The results prove the high effectivity of this treatment, showing high extents of total organic carbon and toxicity removal of the final effluent. We c...

  2. Ferromagnetic behaviour of polyaniline-coated multi-wall carbon nanotubes containing nickel nanoparticles

    Konyushenko, Elena; Kazantseva, N. E.; Stejskal, Jaroslav; Trchová, Miroslava; Kovářová, Jana; Sapurina, I.; Tomishko, M. M.

    2008-01-01

    Roč. 320, 3-4 (2008), s. 231-240. ISSN 0304-8853 R&D Projects: GA AV ČR IAA4050313; GA AV ČR IAA400500504; GA MŠk ME 847; GA ČR GA202/06/0419 Institutional research plan: CEZ:AV0Z40500505 Keywords : multi-wall carbon nanotube * conducting polymer * polyaniline coating Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.283, year: 2008

  3. Multiwalled Carbon Nanotube-TiO2 Nanocomposite for Visible-Light-Induced Photocatalytic Hydrogen Evolution

    2014-01-01

    Multiwalled carbon nanotube- (MWCNT-) TiO2 nanocomposite was synthesized via hydrothermal process and characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, field emission scanning electron microscope, thermogravimetry analysis, and N2 adsorption-desorption isotherms. Appropriate pretreatment on MWCNTs could generate oxygen-containing groups, which is beneficial for forming intimate contact between MWCNTs and TiO2 and leads to a higher thermal stability of MWCNT-TiO2 nan...

  4. Humidity Sensitivity of Multi-Walled Carbon Nanotube Networks Deposited by Dielectrophoresis

    Tianhong Cui; Zhaoying Zhou; Rui Han; Litao Liu; Xiongying Ye; Kang Wu

    2009-01-01

    This paper presents an investigation on the humidity sensitivity of deposited multi-walled carbon nanotube (MWCNT) networks using ac dielectrophoresis (DEP) between interdigitated electrodes (IDEs). MWCNTs dispersed in ethanol were trapped and enriched between IDEs on a Si/SiO2 substrate under a positive DEP force. After the DEP process, the ethanol was evaporated and the MWCNT network on a substrate with IDEs was put into a furnace for repeated thermal annealing. It was found that the resist...

  5. Optimization and Modeling of Hexavalent Chromium Removal from Aqueous Solution Via Adsorption on Multiwalled Carbon Nanotubes

    Mina Gholipour; Hassan Hashemipour Rafsanjani; Ataollah Soltani Goharrizi

    2011-01-01

    Hexavalent chromium and its derivatives are potential pollutant due to their mortal affects. Therefore, It is essential to remove these components from wastewaters before disposal. Adsorption can be effective and versatile method for removing of hexavalent chromium. In this article, removal of hexavalent chromium via adsorption on multiwalled carbon nanotubes was investigated as a function of adsorbent dosage, initial solution pH, initial Cr(VI) concentrations, contact time and temperature. T...

  6. Mapping functional groups on oxidised multi-walled carbon nanotubes at the nanometre scale

    Goode, A. E.; Hine, N. D. M.; Chen, S.; Bergin, S. D.; Shaffer, M. S. P.; Ryan, M. P.; Haynes, P. D.; Porter, A. E.; McComb, D. W.

    2014-01-01

    Despite voluminous research on the acid oxidation of carbon nanotubes (CNTs), there is a distinct lack of experimental results showing distributions of functional groups at the nanometre length scale. Here, functional peaks have been mapped across individual multi-walled CNTs with low-dose, monochromated electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). Density functional theory simulations show that the EELS features are consistent with oxygena...

  7. Electromechanical Behavior of Chemically Reduced Graphene Oxide and Multi-walled Carbon Nanotube Hybrid Material

    Benchirouf, Abderrahmane; Müller, Christian; Kanoun, Olfa

    2016-01-01

    In this paper, we propose strain-sensitive thin films based on chemically reduced graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) without adding any further surfactants. In spite of the insulating properties of the thin-film-based GO due to the presence functional groups such as hydroxyl, epoxy, and carbonyl groups in its atomic structure, a significant enhancement of the film conductivity was reached by chemical reduction with hydro-iodic acid. By optimizing the MWCNT content,...

  8. Structural ordering of multi-walled carbon nanotubes (MWCNTs) caused by gamma (γ)-ray irradiation

    Multi-walled carbon nanotubes (MWCNTs) were irradiated by Gamma (γ)-rays in air with absorbed doses of 25 and 50 kGy. As a result of γ-ray irradiation, the inter-wall distance of MWCNTs was decreased and their graphitic order was improved. The reduction in inter-wall distance and structural ordering was improved with the increasing dosage of irradiation. Experimental evidences are provided by powder XRD and micro-Raman analyses

  9. Pure-Nickel-Coated Multiwalled Carbon Nanotubes Prepared by Electroless Deposition

    Arai, Susumu; Kobayashi, Mitsuhiro; Yamamoto, Tohru; Endo, Morinobu

    2010-01-01

    Pure-nickel-coated multiwalled carbon nanotubes (MWCNTs) have been prepared by electroless deposition. Gluconic acid and hydrazine were respectively used as the complexing and reducing agents for nickel ions. The deposits were heat-treated. The microstructures and magnetic properties of the deposits were examined. The MWCNTs were homogeneously coated with pure nickel and their surfaces were relatively bumpy. These pure-nickel-coated MWCNTs exhibited ferromagnetism and had higher magnetization...

  10. Multiwall carbon nanotube-filled natural rubber: Electrical and mechanical properties

    Bokobza, L.

    2012-01-01

    The influence of multiwall carbon nanotube (MWNTs) contents on electrical and mechanical properties of MWNTs-reinforced natural rubber (NR) composites is studied. The volume resistivity of the composites decreases with increasing the MWNTs content and the electrical percolation threshold is reached at less than 1 phr of MWNTs (phr = parts of filler by weight per hundred parts of rubber). This is caused by the formation of conductive chains in the composites. Electrical measurements under unia...

  11. Magnetic evidence for hot superconductivity in multi-walled carbon nanotubes

    Zhao, Guo-meng; Beeli, Pieder

    2005-01-01

    We report magnetic measurements up to 1200 K on three different multi-walled carbon nanotube mat samples using Quantum Design vibrating sample magnetometers. Three different samples prepared from arc discharge or chemical vapor deposition contain magnetic impurities ranging from about 100 ppm to about 1.5%. Our precise magnetic data clearly show two superconducting transitions, one at temperatures between 533 K and 700 K, and another at about 1200 K. The first transition temperature T_cJ, whi...

  12. Adsorption of tetracycline from aqueous solutions onto multi-walled carbon nanotubes with different oxygen contents

    Fei Yu; Jie Ma; Sheng Han

    2014-01-01

    Oxidized multi-walled carbon nanotubes (MWCNTs) with different oxygen contents were investigated for the adsorption of tetracycline (TC) from aqueous solutions. As the surface oxygen content of the MWCNTs increased, the maximum adsorption capacity and adsorption coefficient of TC increased to the largest values and then decreased. The relation can be attributed to the interplay between the nanotubes' dispersibility and the water cluster formation upon TC adsorption. The overall adsorption kin...

  13. Multi-walled carbon nanotube instillation impairs pulmonary function in C57BL/6 mice

    Walters Dianne M; Rao Apparao M; Ke Pu Chun; Chen Pengyu; Podila Ramakrishna; Katwa Pranita; Wang Xiaojia; Wingard Christopher J; Brown Jared M

    2011-01-01

    Abstract Background Multi-walled carbon nanotubes (MWCNTs) are widely used in many disciplines due to their unique physical and chemical properties. Therefore, some concerns about the possible human health and environmental impacts of manufactured MWCNTs are rising. We hypothesized that instillation of MWCNTs impairs pulmonary function in C57BL/6 mice due to development of lung inflammation and fibrosis. Methods MWCNTs were administered to C57BL/6 mice by oropharyngeal aspiration (1, 2, and 4...

  14. Humidity Sensor Based on Multi-Walled Carbon Nanotube Thin Films

    Cao, C. L.; Hu, C. G.; Fang, L.; Wang, S. X.; Y. S. TIAN; Pan, C. Y.

    2011-01-01

    The properties of the humidity sensors made of chemically treated and untreated multi-walled carbon nanotube (MWCNT) thin films are investigated systematically. It shows that both the chemically treated and untreated MWCNT thin films demonstrate humidity sensitive properties, but the former have stronger sensitivity than the latter. In the range of 11%–98% relative humidity (RH), the resistances of the chemically treated and untreated MWCNT humidity sensors increase 120% and 28%, respectively...

  15. Removal of inorganic mercury from aquatic environments by multi-walled carbon nanotubes

    Yaghmaeian, Kamyar; Khosravi Mashizi, Reza; Nasseri, Simin; Mahvi, Amir Hossein; Alimohammadi, Mahmood; Nazmara, Shahrokh

    2015-01-01

    Background Mercury is considered as a toxic heavy metal in aquatic environments due to accumulation in bodies of living organisms. Exposure to mercury may lead to different toxic effects in humans including damages to kidneys and nervous system. Materials and methods Multi-walled carbon nanotubes (MWCNTs) were selected as sorbent to remove mercury from aqueous solution using batch technique. ICP instrument was used to determine the amount of mercury in solution. Moreover, pH, contact time and...

  16. Plasma Treated Multi-Walled Carbon Nanotubes (MWCNTs) for Epoxy Nanocomposites

    Jie Lian; Xu Han; Lombardo, Stephen J.; Hao Li; Qingsong Yu; Ritts, Andrew C.; Zhenhai Xia

    2011-01-01

    Plasma nanocoating of allylamine were deposited on the surfaces of multi-walled carbon nanotubes (MWCNTs) to provide desirable functionalities and thus to tailor the surface characteristics of MWCNTs for improved dispersion and interfacial adhesion in epoxy matrices. Plasma nanocoated MWCNTs were characterized using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), surface contact angle, and pH change measurements. Mechanical testing results showed...

  17. Load-bearing contribution of multi-walled carbon nanotubes on tensile response of aluminum

    Kurita, Hiroki; Estili, Mehdi; Kwon, Hansang; Miyazaki, Takamichi; Zhou, Weiwei; Silvain, Jean-François; Kawasaki, Akira

    2015-01-01

    International audience We fabricated a uniformly dispersed and aligned multi-walled carbon nanotube reinforced aluminum matrix (Al–MWCNT) composite with minimal work hardening and without interfacial chemical compounds. In this paper, the direct load-bearing contribution of MWCNTs on the Al–MWCNT composite was investigated in detail for various volume fractions of MWCNTs. For up to 0.6 vol% of MWCNTs, the ultimate tensile strength (UTS) of the Al–MWCNT composite increased with the conserva...

  18. EMI shielding effectiveness of silver nanoparticle-decorated multi-walled carbon nanotube sheets

    Zhao, Wenming; Mei LI; Zhang, Zhongyi; Peng, Hua-Xin

    2010-01-01

    With the aim of exploring the excellent properties of multi-walled carbon nanotubes (MWNTs) in modern composite technologies, various macrostructures of nanotubes have been developed from one to three dimensions, e.g. fibers, networks, sheets (buckypapers) and pellets. The MWNT sheets discussed here were fabricated by a vacuum filtration procedure, a process that has potential for large-scale manufacturing. In order to further enhance the transport properties of MWNT sheets by reducing the co...

  19. Liquid sensing properties of melt processed polypropylene/poly(ε-caprolactone) blends containing multiwalled carbon nanotubes

    Pötschke, Petra; Kobashi, Kazufumi; Villmow, Tobias; Andres, Timo; Paiva, Maria Conceição; Covas, José António

    2011-01-01

    Abstract The sensing properties of polypropylene (PP)/poly(?-caprolactone) (PCL) blends containing multiwalled carbon nanotubes (MWNT) were studied in terms of their electrical resistance change in presence of liquids (solvents). The preparation of co-continuous blends based on the double percolation concept was done by melt mixing of electrically conductive PCL composites containing 3wt.% MWNT and neat PP in ratios of 30:70, 40:60, and 50:50. The electrical resistance change of th...

  20. A comparative study of enzyme immobilization strategies for multi-walled carbon nanotube glucose biosensors

    SHI, JIN; Claussen, Jonathan C.; McLamore, Eric S.; ul Haque, Aeraj; Jaroch, David; Diggs, Alfred; Calvo-Marzal, Percy; Rickus, Jenna; Porterfield, D. Marshall

    2011-01-01

    This work addresses the comparison of different strategies for improving biosensor performance using nanomaterials. Glucose biosensors based on commonly applied enzyme immobilization approaches, including sol-gel encapsulation approaches and glutaraldehyde cross-linking strategies, were studied in the presence and absence of multi-walled carbon nanotubes (MWNTs). Although direct comparison of design parameters such as linear range and sensitivity is intuitive, this comparison alone is not an ...

  1. Low temperature phase transformations in 4-cyano-4'-pentylbiphenyl (5CB) filled by multiwalled carbon nanotubes

    Lebovka, N.; Melnyk, V.; Mamunya, Ye.; Klishevich, G.; Goncharuk, A.; Pivovarova, N.

    2013-01-01

    The effects of multiwalled carbon nanotubes (NTs) on low-temperature phase transformations in 5CB were studied by means of differential scanning calorimetry (DSC), low-temperature photoluminescence and measurements of electrical conductivity. The concentration of NTs was varied within 0-1% wt. The experimental data, obtained for pure 5CB by DSC and measurements of photoluminescence in the heating mode, evidenced the presence of two crystallization processes at T->229 K and T->262 K, which cor...

  2. Functionalized multi-walled carbon nanotube paper for monitoring chemical vapors

    P. Slobodian; Říha, P.; Olejník, R.; Saha, P.

    2015-01-01

    The multi-walled carbon nanotube paper is prepared by vacuum filtration of pure nanotubes and their functionalized forms prepared by KMnO.sub.4./sub. and H.sub.2./sub.O.sub.2./sub. oxidation or by grafting with Poly(methyl methacrylate) (PMMA) and polypyrrole to form sensory nanotubes layer for detection of volatile organic compounds in air. The selected compounds for experimentation (acetone, diethyl ether, isopentane, methanol, tetrahydrofuran) have different polarities and volume fractions...

  3. Highly enhanced vapor sensing of multiwalled carbon nanotube network sensors by n-butylamine functionalization

    P. Slobodian; Riha, P.; Cavallo, P.; Barbero, C. A.; R. Benlikaya; Cvelbar, U.; Petras, D.; Saha, P.

    2014-01-01

    The sensing of volatile organic compounds by multiwall carbon nanotube networks of randomly entangled pristine nanotubes or the nanotubes functionalized by n-butylamine, which were deposited on polyurethane supporting electrospinned nonwoven membrane, has been investigated. The results show that the sensing of volatile organic compounds by functionalized nanotubes considerably increases with respect to pristine nanotubes. The increase is highly dependent on used vapor polarity. For the cas...

  4. Synthesis of Multiwalled Carbon Nanotubes-Titania Nanomaterial for Desulfurization of Model Fuel

    Saleh, Tawfik A.; Mohammad N. Siddiqui; Abdulrahman A. Al-Arfaj

    2014-01-01

    This work reported on the development of novel nanomaterials of multiwalled carbon nanotubes doped with titania (CNT/TiO2) for the adsorptive desulfurization of model fuel oils. Various analytical techniques such as field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) were used for the characterization of the nanomaterials. The initial results indicated the effectiveness of the prepared CNT/TiO2 nan...

  5. Evaluation of Maternal Toxicity in Rats Exposed to Multi-Wall Carbon Nanotubes during Pregnancy

    Lim, Jeong-Hyeon; Kim, Sung-Hwan; Lee, In-Chul; Moon, Changjong; Kim, Sung-Ho; Shin, Dong-Ho; Kim, Hyoung-Chin; Kim, Jong-Choon

    2011-01-01

    Objectives The present study investigated the potential adverse effects of multi-wall carbon nanotubes (MWCNTs) on pregnant dams and embryonic development following maternal exposure in rats. Methods MWCNTs were orally administered to pregnant rats from gestational day (GD) 6 through 19 at dose levels of 0, 8, 40, 200, and 1000 mg/kg/day. During the test period, clinical signs, mortality, body weights, food consumption, serum biochemistry, oxidant-antioxidant status, gross findings, organ wei...

  6. Biosynthesis of Bacterial Cellulose/Carboxylic Multi-Walled Carbon Nanotubes for Enzymatic Biofuel Cell Application

    Pengfei Lv; Quan Feng; Qingqing Wang; Guohui Li; Dawei Li; Qufu Wei

    2016-01-01

    Novel nanocomposites comprised of bacterial cellulose (BC) with carboxylic multi-walled carbon nanotubes (c-MWCNTs) incorporated into the BC matrix were prepared through a simple method of biosynthesis. The biocathode and bioanode for the enzyme biological fuel cell (EBFC) were prepared using BC/c-MWCNTs composite injected by laccase (Lac) and glucose oxidase (GOD) with the aid of glutaraldehyde (GA) crosslinking. Biosynthesis of BC/c-MWCNTs composite was characterized by digital photos, scan...

  7. Multi-walled carbon nanotubes (MWCNTs) functionalized with amino groups by reacting with supercritical ammonia fluids

    For the first time, supercritical ammonia fluid was utilized to simply functionalize multi-walled carbon nanotube (MWCNT) with amino groups. The successful amino functionalization of MWCNTs was proven and the physicochemical properties of MWCNTs before and after supercritical ammonia fluids modifications were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM) and Raman spectroscopy. The results also indicated that the supercritical ammonia fluids had the visible effects on the nanostructure of carbon nanotubes. Our novel modification approach provides an easy way to modify MWCNTs with amino groups, which is very useful for realizing 'carbon nanotube economy' in the near future.

  8. Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

    2009-01-01

    The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported. The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition. High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc). The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT. The experimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction. There was local cross-section deformation on MWCNTs at the interface of hetero-junction. These results involve the important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.

  9. Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

    WANG ZhenXia; LI XinNian; REN CuiLan; YONG ZhenZhong; ZHU JianKang; LUO WenYun; FANG XiaoMing

    2009-01-01

    The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported.The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition.High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc).The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT.The ex-perimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction.There was local cross-section deformation on MWCNTs at the interface of hetero-junction.These results involve the Important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.

  10. Multiwalled carbon nanotubes as masks against carbon and argon irradiation. A molecular dynamics study

    Denton, Cristian D.; Moreno-Marín, Juan Carlos; Heredia-Avalos, Santiago

    2016-04-01

    Experiments showed that multiwalled carbon nanotubes (MWCNT) can be used as masks against irradiation to create metallic nanowires in a substrate. In order to understand the limitations of this application, it is interesting to know the energy and number of carbon atoms emerging from the MWCNT after the irradiation and how the structure of the MWCNT is modified. Using a molecular dynamics code that we have previously developed, we have simulated the continuous irradiation of MWCNT with carbon and argon projectiles. We have obtained that the use of carbon instead of argon to irradiate the MWCNT increases de effectiveness of the MWCNTs as masks, due to the ability of the carbon projectiles to be part of the MWCNT structure and partially mend the damage produced during irradiation. We have analyzed the number, energy, and spatial distribution of the recoils generated during irradiation and the change of the MWCNT structure as a function of the incident energy (100 and 500 eV), fluence (up to 4.5 ·1015ions /cm2), and number of shells (up to 5-shells) of the MWCNT. These results determine the effectiveness of MWCNT as a mask, being useful to understand whether the atoms emerging from the MWCNT produce damage in the substrate or not. We find that for carbon projectiles the efficiency of MWCNT as masks does not depend much on the fluence, but on the number of nanotube shells and projectile incident energy. On the other hand, for a given nanotube and fluence, we observe a threshold incident energy below which the nanotube acts as a perfect mask.

  11. Supramolecular modification of multi-walled carbon nanotubes with β-cyclodextrin for better dispersibility

    He, Yi, E-mail: 15828515724@163.com, E-mail: heyi@swpu.edu.cn; Xu, Zhonghao [Southwest Petroleum University, State Key Lab of Oil and Gas Reservoir Geology and Exploitation (China); Yang, Qiangbin; Wu, Feng; Liang, Lv [Southwest Petroleum University, School of Chemistry and Chemical Engineering (China)

    2015-01-15

    A novel hybrid material based on multi-walled carbon nanotubes was synthesized using organic synthesis, and the structures of multi-walled carbon nanotube derivatives were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, {sup 1}H NMR spectroscopy, transmission electron microscopy, and scanning electron microscope. The analytical results indicated that β-cyclodextrin (β-CD) was anchored to the surface of Multi-walled carbon nanotubes (MWCNTs, OD: 10–20 nm, length: 10–30 μm) and dispersion experiments exhibited that the introduction of β-CD onto the MWCNTs would dramatically enhance the dispersion of MWCNTs in both ethanol and water media; the suspensions were found to be very stable for 2 months, and the results of this technique confirmed the experimental results. This novel technique would provide a new, simple, and facile route to prepare the modified nanomaterials based on silane-coupling agent and β-CD, and the obtained modified nanomaterials have great potential practical significance and theoretical value to develop the novel organic–inorganic hybrid material, which was very useful for water treatment and biological medicine.

  12. Ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotube mixtures

    Kozulin, Alexander A., E-mail: kozulyn@ftf.tsu.ru; Vorozhtsov, Sergey A., E-mail: vorn1985@gmail.com; Kulkov, Sergey S.; Kulkov, Sergey N. [National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Teipel, U. [Georg Simon Ohm University of Applied Sciences, Nuremberg (Germany)

    2015-10-27

    Comprehensive investigations of aluminum nanopowders, multi-walled carbon nanotubes, and aluminum mixtures with multi-walled carbon nanotubes subjected to ultrasonic deagglomeration in a liquid medium were performed, using microstructural, X-ray diffraction, thermogravimetric, and calorimetric analyses, and specific surface area measurements. The regime of ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotubes in a liquid medium is described, during which the division of large agglomerates and creation of homogeneous distribution of mixtures components in the volume takes place. It was determined that ultrasonic treatment influences the morphology and crystalline structure of investigated mixtures, contributes to the appearance of X-ray amorphous phase, decreases the specific surface area of the aluminum nanopowder from 13 to 12 m{sup 2}/g, and increases the pore volume and average size from 0.04 to 0.06 cm{sup 3}/g and from 12 to 19 nm, respectively. The size of coherently-diffracting domain was determined by the X-ray diffraction analysis is close to that estimated from the specific surface area and corresponds to average crystallites size in the materials under study.

  13. Ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotube mixtures

    Kozulin, Alexander A.; Vorozhtsov, Sergey A.; Kulkov, Sergey S.; Teipel, U.; Kulkov, Sergey N.

    2015-10-01

    Comprehensive investigations of aluminum nanopowders, multi-walled carbon nanotubes, and aluminum mixtures with multi-walled carbon nanotubes subjected to ultrasonic deagglomeration in a liquid medium were performed, using microstructural, X-ray diffraction, thermogravimetric, and calorimetric analyses, and specific surface area measurements. The regime of ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotubes in a liquid medium is described, during which the division of large agglomerates and creation of homogeneous distribution of mixtures components in the volume takes place. It was determined that ultrasonic treatment influences the morphology and crystalline structure of investigated mixtures, contributes to the appearance of X-ray amorphous phase, decreases the specific surface area of the aluminum nanopowder from 13 to 12 m2/g, and increases the pore volume and average size from 0.04 to 0.06 cm3/g and from 12 to 19 nm, respectively. The size of coherently-diffracting domain was determined by the X-ray diffraction analysis is close to that estimated from the specific surface area and corresponds to average crystallites size in the materials under study.

  14. Ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotube mixtures

    Comprehensive investigations of aluminum nanopowders, multi-walled carbon nanotubes, and aluminum mixtures with multi-walled carbon nanotubes subjected to ultrasonic deagglomeration in a liquid medium were performed, using microstructural, X-ray diffraction, thermogravimetric, and calorimetric analyses, and specific surface area measurements. The regime of ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotubes in a liquid medium is described, during which the division of large agglomerates and creation of homogeneous distribution of mixtures components in the volume takes place. It was determined that ultrasonic treatment influences the morphology and crystalline structure of investigated mixtures, contributes to the appearance of X-ray amorphous phase, decreases the specific surface area of the aluminum nanopowder from 13 to 12 m2/g, and increases the pore volume and average size from 0.04 to 0.06 cm3/g and from 12 to 19 nm, respectively. The size of coherently-diffracting domain was determined by the X-ray diffraction analysis is close to that estimated from the specific surface area and corresponds to average crystallites size in the materials under study

  15. The surface modifications of multi-walled carbon nanotubes for multi-walled carbon nanotube/poly(ether ether ketone) composites

    Cao, Zongshuang; Qiu, Li; Yang, Yongzhen; Chen, Yongkang; Liu, Xuguang

    2015-10-01

    The effects of surface modifications of multi-walled carbon nanotubes (MWCNTs) on the morphology, dynamic mechanical and tribological properties of multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites have been investigated. MWCNTs were treated with mixed acids to obtain acid-functionalized MWCNTs. Then the acid-functionalized MWCNTs were modified with ethanolamine (named e-MWCNTs). The MWCNT/PEEK composites were prepared by a solution-blending method. A more homogeneous distribution of e-MWCNTs within the composites was found with scanning electron microscopy. Dynamic mechanical analysis demonstrated a clear increase in the storage modulus of e-MWCNT/PEEK composites because of the improved interfacial adhesion strength between e-MWCNTs and PEEK. Furthermore, the presence of e-MWCNTs caused an enhancement in the glass transition temperature of the composites. Wear tests have shown that the friction coefficient of e-MWCNT/PEEK composites decreased significantly during the test after the running-in period. This suggests that there is an obvious improvement in tribological properties of e-MWCNT/PEEK composites. Overall, the e-MWCNT/PEEK composites have exhibited improved properties and are promising for their applications in industry.

  16. Reinforcement of Multiwalled Carbon Nanotube in Nitrile Rubber: In Comparison with Carbon Black, Conductive Carbon Black, and Precipitated Silica

    Atip Boonbumrung

    2016-01-01

    Full Text Available The properties of nitrile rubber (NBR reinforced by multiwalled carbon nanotube (MWCNT, conductive carbon black (CCB, carbon black (CB, and precipitated silica (PSi were investigated via viscoelastic behavior, bound rubber content, electrical properties, cross-link density, and mechanical properties. The filler content was varied from 0 to 15 phr. MWCNT shows the greatest magnitude of reinforcement considered in terms of tensile strength, modulus, hardness, and abrasion resistance followed by CCB, CB, and PSi. The MWCNT filled system also exhibits extremely high levels of filler network and trapped rubber even at relatively low loading (5 phr leading to high electrical properties and poor dynamic mechanical properties. Although CCB possesses the highest specific surface area, it gives lower level of filler network than MWCNT and also gives the highest elongation at break among all fillers. Both CB and PSi show comparable degree of reinforcement which is considerably lower than CCB and MWCNT.

  17. Preparation of Hydroxypropyl-β-cyclodextrin Cross-linked Multi-walled Carbon Nanotubes and Their Application in Enantioseparation of Clenbuterol

    Yu Jingang; Huang Dushu; Huang Kelong; Hong Yong

    2011-01-01

    A method of cross-linking multi-walled carbon nanotubes by a nucleophilic substitution of brominated multi-walled carbon nanotubes using hydroxypropyl-β-cyclodextrin anions was studied. The modified multi-walled carbon nanotube samples were characterized using thermogravimetric analysis, energy-dispersive X-ray spectros-copy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. The hydroxypropyi-β-cyclodextrin modified multi-walled carbon nanotubes were used as a chiral stationary phase additive for thin-layer chromatography to separate clenbuterol enantiomers, and the chiral separation factor was increased.

  18. Cyclodextrin polyurethanes polymerized with multi-walled carbon nanotubes: Synthesis and characterization

    Insoluble cyclodextrin polymers co-polymerized with multi-walled carbon nanotubes were synthesized by polymerizing β-cyclodextrin with acid-functionalized multi-walled carbon nanotubes and diisocyanate linkers; hexamethylene- and toluene-2,4-diisocyanate. The polymers are useful in removing some organic pollutants from water, and we now report the full characterization of these polymers using infrared spectroscopy (IR), Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and thermal techniques such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The polymers could be synthesized as either powders or amorphous solids. Results of the IR analysis showed the presence of functional groups such as C=O, C=C, C-H and C-O, indicating that polymerization indeed took place. Characterization of the polymers by scanning electron microscopy and BET analysis showed that these polymers had a spongy appearance indicating a hierarchical pore structure. Incorporation of small amounts (<5%) of multi-walled nanotubes (MWNTs) improved the thermal stability of the polymers. This observation was further confirmed by differential scanning calorimetry (DSC) measurements

  19. Effects of strain rates and temperatures on the mechanical properties of multi-walled carbon nanotubes

    This paper reports the results of an investigation of the dynamic mechanical properties of multi-walled armchair and zigzag nanotubes under different strain rates and environmental temperatures. Based on a molecular structural mechanics model, the covalent bonds are treated as a two dimensional beam element and van der Waals forces between two adjacent tubes are firstly simulated by a nonlinear spring. The corresponding force constants of bond stretching, bond angle bending and torsional resistance in different environmental temperatures can be, respectively, obtained by computing the variation of chemical bond lengths. The result obtained reveals that the dynamic Young's modulus of the effective nanotube material increases as the strain rate increases, and decreases as the environmental temperature increases; the effect of layer numbers of multi-walled carbon nanotubes (MWCNTs) on the dynamic Young's modulus of the effective nanotube material is dependent on strain rates and environmental temperatures

  20. In Situ Tests of Multiwalled Carbon Nanotubes with Strength Close to Theoretical Predictions

    Using MEMS technology and transmission electron microscopy we show experimentally multiwalled carbon nanotubes with a mean fracture strength of larger than 100 GPa, which exceeds the earlier observations by a factor of approximately 3. These results are in excellent agreement with quantum-mechanical estimations. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging is used to directly determine the number of fractured shells and the chirality of the outer shell. Electron irradiation at 200 keV for 10, 100 and 1800s lead to improvements of the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. This procedure is a cost effective way of customizing the properties of multiwall nanotubes for many applications of interest ranging from nanocomposites to nanodevices

  1. Unraveling the growth of vertically aligned multi-walled carbon nanotubes by chemical vapor deposition

    The interaction between the main operational variables during the growth of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) by catalytic chemical vapor deposition is studied. In this contribution, we report the influence of the carbon source (i.e. acetylene, ethylene and propylene), the reaction/activation temperature, the rate of heating, the reaction time, the metal loading, and the metallic nanoparticle size and distribution on the growth and alignment of carbon nanotubes. Fe/Al thin films deposited onto silicon samples by electron-beam evaporation are used as catalyst. A phenomenological growth mechanism is proposed to explain the interaction between these multiple factors. Three different outcomes of the synthesis process are found: i) formation of forests of non-aligned, randomly oriented multi-walled carbon nanotubes, ii) growth of vertically aligned tubes with a thin and homogeneous carbonaceous layer on the top, and iii) formation of vertically aligned carbon nanotubes. This carbonaceous layer (ii) has not been reported before. The main requirements to promote vertically aligned carbon nanotube growth are determined. (paper)

  2. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA–MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species. (papers)

  3. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

    2014-04-01

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

  4. Multiwalled Carbon Nanotube Synthesis Using Arc Discharge with Hydrocarbon as Feedstock

    Chaudhary, K. T.; Z. H. Rizvi; Bhatti, K. A.; Ali, J; P. P. Yupapin

    2013-01-01

    Synthesis of multiwalled carbon nanotube (MWCNT) by arc discharge process is investigated with methane (CH4) as background and feedstock gas. The arc discharge is carried out between two graphite electrodes for ambient pressures 100, 300, and 500 torr and arc currents 50, 70, and 90 A. Plasma kinetics such as the density and temperature for arc discharge carbon plasma is determined to find out the contribution of physical parameters as arc current and ambient pressure on the plasma dynamics a...

  5. The enhanced alcohol sensing response of multiwalled carbon nanotube networks induced by alkyl diamine treatment

    Benlikaya, R.; Slobodian, P.; Říha, Pavel; Olejník, R.

    2014-01-01

    Roč. 201, October (2014), s. 122-130. ISSN 0925-4005 R&D Projects: GA MŠk(CZ) CZ.1.07/2.3.00/20.0104 Grant ostatní: UTB Zlín(CZ) IGA/FT/2013/018; GA MŠk(CZ) ED2.1.00/03.0111 Institutional research plan: CEZ:AV0Z20600510 Institutional support: RVO:67985874 Keywords : carbon nanotubes * multiwalled carbon nanotube networks * vapor sensing * linear alcohols * alkyl diamine treatment Subject RIV: BK - Fluid Dynamics Impact factor: 4.097, year: 2014

  6. Methane preconcentration in a microtrap using multiwalled carbon nanotubes as sorbents.

    Saridara, Chutarat; Ragunath, Smruti; Pu, Yong; Mitra, Somenath

    2010-09-10

    The GC monitoring of green house gases is a challenging task because the concentration of organic species such as methane are relatively low (ppm to ppb) and their analysis requires some level of preconcentration. Since methane is highly volatile, it is not easily retained on conventional sorbents. In this paper we present multiwalled carbon nanotubes (MWNTs) as an effective sorbent for a microtrap designed for methane preconcentration. Its performance was compared to other commercially available carbon based sorbents, and it was found to be the most effective sorbent in terms of breakthrough volume and enthalpy of adsorption. PMID:20850589

  7. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  8. Parameterizing A Surface Water Model for Multiwalled Carbon Nanotubes

    The unique electronic, mechanical, and structural properties of carbon nanotubes (CNTs) has lead to increasing production of these versatile materials; currently, the use of carbon-based nanomaterials in consumer products is second only to that of nano-scale silver. Although ther...

  9. Effects of nitrogen-doped multi-walled carbon nanotubes compared to pristine multi-walled carbon nanotubes on human small airway epithelial cells

    Nitrogen-doped multi-walled carbon nanotubes (ND-MWCNTs) are modified multi-walled carbon nanotubes (MWCNTs) with enhanced electrical properties that are used in a variety of applications, including fuel cells and sensors; however, the mode of toxic action of ND-MWCNT has yet to be fully elucidated. In the present study, we compared the interaction of ND-MWCNT or pristine MWCNT-7 with human small airway epithelial cells (SAEC) and evaluated their subsequent bioactive effects. Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction suggested the presence of N-containing defects in the lattice of the nanotube. The ND-MWCNTs were determined to be 93.3% carbon, 3.8% oxygen, and 2.9% nitrogen. A dose–response cell proliferation assay showed that low doses of ND-MWCNT (1.2 μg/ml) or MWCNT-7 (0.12 μg/ml) increased cellular proliferation, while the highest dose of 120 μg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6 h and were internalized by 24 h. ROS were elevated at 6 and 24 h in ND-MWCNT exposed cells, but only at 6 h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2 μg/ml of ND-MWCNT or MWCNT-7 in a time and material-dependent manner, possibly suggesting potential damage or alterations to cell cycle machinery. Our results indicate that ND-MWCNT induce effects in SAEC over a time and dose-related manner which differ from MWCNT-7. Therefore, the physicochemical characteristics of the materials appear to alter their biological effects

  10. Cement Pastes and Mortars Containing Nitrogen-Doped and Oxygen-Functionalized Multiwalled Carbon Nanotubes

    Mauricio Martínez-Alanis

    2016-01-01

    Full Text Available Cement pastes and mortars based on ordinary Portland cement containing nitrogen-doped multiwalled carbon nanotubes (MWCNT-Nx or oxygen-functionalized multiwalled carbon nanotubes (MWCNT-Ox are investigated. To incorporate MWCNTs into the cementitious matrix, the as-produced carpets are dispersed over periods of 1 and 2 hours in distilled water at pH levels of 1 and 7. The cement pastes are prepared by adding 0.1 wt% of MWCNTs to cement powder, followed by characterization with SEM and X-ray diffraction (XRD at an early age (first hours of hydration. The mortars are mechanically characterized during the hydration process for a period of 28 days. SEM characterization of cement pastes revealed that the carbon nanotubes are well incorporated in the cementitious matrix, with the hydrated cement grains interconnected by long carbon nanotubes. XRD characterizations demonstrated that, during the hydration of cement pastes, different peaks emerged that were associated with ettringite, hydrated calcium silicate, and calcium hydroxide, among other structures. Results of the compressive strength measurements for mortars simultaneously mixed with MWCNT-Nx and MWCNT-Ox reached an increment of approximately 30% in compressive strength. In addition, density functional theory calculations were performed in nitrogen-doped and oxygen-functionalized carbon nanotubes interacting with a cement grain.

  11. On Young’s modulus of multi-walled carbon nanotubes

    K T Kashyap; R G Patil

    2008-04-01

    Carbon nanotubes (CNTs) were discovered by Iijima in 1991 as the fourth form of carbon. Carbon nanotubes are the ultimate carbon fibres because of their high Young’s modulus of ≈ 1 TPa which is very useful for load transfer in nanocomposites. In the present work, CNT/Al nanocomposites were fabricated by the powder metallurgy technique and after extrusion of the nanocomposites bright field transmission electron microscopic (TEM) studies were carried out. From the TEM images so obtained, a novel method of ascertaining the Young’s modulus of multi-walled carbon nanotubes is worked out in the present paper which turns out to be 0.9 TPa which is consistent with the experimental results.

  12. Fabrication And Properties Of Silver Based Multiwall Carbon Nanotube Composite Prepared By Spark Plasma Sintering Method

    Lis M.

    2015-06-01

    Full Text Available The paper presents results of investigations of the obtained nanocomposite materials based on silver with addition of multiwall carbon nanotubes. The powder of carbon nanotubes content from 0.1 to 3 wt. % was produced by application of powder metallurgy methods, through mixing and high-energetic milling, and also chemical methods. Modification of carbon nanotubes included electroless deposition of silver particles on the carbon nanotube active surfaces and chemical reduction with strong reducing agent – sodium borohydride (NaBH4. The obtained powder mixtures were consolidated by SPS – Spark Plasma Sintering method. The formed composites were subjected to tests of relative density, electrical conductivity and electro-erosion properties. Detailed examinations of the structure with application of X-ray microanalysis, with consideration of carbon nanotubes distribution, were also carried out. The effect of manufacturing methods on properties of the obtained composites was observed.

  13. Carbon dioxide captured by multi-walled carbon nanotube and activated charcoal: A comparative study

    Khalili Soodabeh

    2013-01-01

    Full Text Available this study, the equilibrium adsorption of CO2 on activated charcoal (AC and multi-walled carbon nanotube (MWCNT were investigated. Experiments were performed at temperature range of 298-318 K and pressures up to 40 bars. The obtained results indicated that the equilibrium uptakes of CO2 by both adsorbents increased with increasing pressure and decreasing temperature. In spite of lower specific surface area, the maximum amount of CO2 uptake achieved by MWCNT at 298K and 40 bars were twice of CO2 capture by AC (15 mmol.g-1 compared to 7.93 mmol.g-1. The higher CO2 captured by MWCNT can be attributed to its higher pore volume and specific structure of MWCN T such as hollowness and light mass which had greater influence than specific surface area. The experimental data were analyzed by means of Freundlich and Langmuir adsorption isotherm models. Following a simple acidic treatment procedure increased marginally CO2 capture by MWCNT over entire range of pressure, while for AC this effect appeared at higher pressures. Small values of isosteric heat of adsorption were evaluated based on Clausius-Clapeyron equation showed the physical nature of adsorption mechanism. The high amount of CO2 capture by MWCNT renders it as a promising carrier for practical applications such as gas separation.

  14. Sodium insertion/extraction from single-walled and multi-walled carbon nanotubes: The differences and similarities

    Goonetilleke, Damian; Pramudita, James C.; Choucair, Mohammad; Rawal, Aditya; Sharma, Neeraj

    2016-05-01

    A comparative study on the sodium-ion insertion and extraction of commercially-available multi-wall and single-wall carbon nanotubes is reported. Single-wall carbon nanotubes exhibit charge/discharge capacities of 126 mA h g-1 and multi-wall carbon nanotubes produce a lower capacity of 28 mA h g-1 after 50 cycles at 25 mA g-1. To understand these differences, a combination of X-ray diffraction and solid state nuclear magnetic resonance measurements were performed at various states of sodium insertion and extraction.23Na nuclear magnetic resonance studies, a technique previously rarely used for characterising electrodes from sodium-ion batteries, shows differences in the sodium chemical environment near multi-wall compared to single-wall carbon nanotubes with distinct sodium sites found to be active during sodium insertion and extraction for the carbon nanotubes. Both types of carbon nanotubes show a similar amount of reversible sodium available for insertion/extraction reactions, but multi-wall carbon nanotubes feature half the initial insertion capacity relative to single-wall carbon nanotubes. The electrochemical performance of the carbon nanotube electrodes are discussed in relation to the observed mechanism of sodium insertion.

  15. Optimization of adsorption phenanthrene on the multi-walled carbon nanotubes

    R. Abedinloo

    2015-11-01

    Full Text Available Introduction: Polycyclic Aromatic Hydrocarbons (PAHs belong to one of the groups of persistent organic pollutants (POPs which are the result of incomplete combustion of organic materials, volcanic eruptions and forest and agricultural fields’ fires in the environment. However, human factors are main source of these pollutions. Nowadays, these compounds are among the main concerns related to the pollutants which, can easily enter into the land and water systems. Absorption of aromatic hydrocarbons and poly-aromatic molecules on the surfaces of carbon nano-tubes (CNTs have increased in recent years. In this study, absorption of phenanthrene (as a representative of aromatic hydrocarbons groups on multi-walled carbon nano-tubes was investigated in organic environment. Material and Method: All experiments were performed in a laboratory environment with a temperature of 24±2.Different variables including the type of solvent, solvent volume, pH of the environment, the absorption time of optimal phenanthrene concentration, and the highest removal efficiency under optimized parameters were obtained. Samples were analyzed using HPLC. Result: Findings showed that methanol with the volume of 10 ml, and the absorption time of 1.5 hours and 1.3 ppm concentration had the maximum absorption efficiency. Environmental pH had no effect on the absorption efficiency. Conclusion: Multi-walled carbon nano-tubes have high absorption capacity for the absorption of phenanthrene. Moreover, in an organic environment, the level of phenanthrene absorption on multi-walled carbon nano-adsorbent was more than 90% and according to the material used was 92%. Day-to-day and within-day reproducibility confirmed the mentioned results.

  16. Synthesis of multiwalled carbon nanotubes from bamboo charcoal and the roles of minerals on their growth

    Multiwalled carbon nanotubes (MWCNTs) were synthesized from bamboo charcoals by chemical vapor deposition in the presence of ethanol vapor. Fresh bamboo culms were first heat treated at 1000–1500 °C to form charcoals. The elemental composition and structure of mineral phases in the bamboo charcoal treated at different temperatures were analyzed. The results showed that Mg2SiO4 and particularly calcium silicate were responsible for the nucleation and growth of MWCNTs at 1200–1400 °C. Transmission electron microscope and energy dispersive X-ray spectrometer observations indicated that the tips of nanotubes synthesized at 1200–1400 °C consist mainly of calcium silicate. Such silicate tips acted as effective catalysts for nanotubes. The growth of MWCNTs followed the vapor–liquid–solid model including an initial decomposition of ethanol vapor into carbon, dissolution of carbon inside molten silicate and final nucleation of nanotubes. -- Graphical abstract: Calcium silicate spheres formed on the surface of the bamboo charcoal after thermal treatments. Multiwalled carbon nanotubes were synthesized by ethanol chemical vapor deposition. The growth of CNTs follows the vapor–liquid–solid mechanism. Uploading of CNTs could increase the specific surface area and the N2 adsorption capacity. Highlights: ► The evolution of minerals in bamboo charcoal under heat treatment is found. ► The roles of minerals in bamboo charcoal in the growth of CNTs are proposed. ► The upload of CNTs increases the specific surface area and the adsorption capacity.

  17. Preparation of Multi-Walled Carbon Nanotube/Amino-Terminated Ionic Liquid Arrays and Their Electrocatalysis towards Oxygen Reduction

    Li Niu; Ari Ivaska; Carita Kvarnström; Rose-Marie Latonen; Zhijuan Wang

    2010-01-01

    Arrays of aligned multi-walled carbon nanotube-ionic liquid (MIL) were assembled on silicon wafers (Si-MIL). Formation of Si-MIL was confirmed by ATR-FTIR, AFM and Raman techniques. The electrochemical measurements indicated that Si-MIL showed good electrocatalysis towards oxygen reduction compared with MIL drop-cast on a glassy carbon electrode.

  18. Ferromagnetic behaviour of anthropogenic multi-walled carbon nanotubes trapped in spider web indoor.

    Sonkar, Sumit Kumar; Tripathi, Kumud Malika; Sarkar, Sabyasachi

    2014-03-01

    Black carbon (BC) (as partly burnt black particulate matter) present indoor are deposited on interior surfaces of the indoors (easily visualize over the blades of electric fan/exhausts and over domestic spider webs) are known to be a potential indoor pollution problem. We detect with the help of indoor spider webs the floating BC contains a significant amount of defective multiwalled carbon nanotubes (MWCNTs) possessing room temperature ferromagnetism. Microscopic studies shows a lot of internal and surfacial defects in these indoor-MWCNTs. Electron paramagnetic resonance (EPR) showed the presence of very stable carbon centred radicals in these indoor-MWCNTs. Room temperature ferromagnetism most importantly originated by the presence of a large amount of unpaired spin frustrated carbon centred radicals (trapped in defects, junctions and fractures) which are inadvertently formed during the pyrolysis of carbonaceous materials through routine domestic activities. PMID:24745259

  19. Adsorption and adhesion of blood proteins and fibroblasts on multi-wall carbon nanotubes

    2009-01-01

    This article concerns the investigation of blood protein adsorption on carbon paper and multi-wall carbon nanotubes (MWCNTs). Mouse fibroblast cell adhesion and growth on MWCNTs was also studied. The results showed that fibrinogen adsorption on carbon paper was much lower than that on MWCNTs, which means that platelets readily aggregate on the surface of MWCNTs. Mouse fibroblast cells implanted on MWCNTs tended to grow more prolifically than those implanted on carbon paper. The cell concentration observed on MWCNTs increased from 1.2×105/mL for a single day culture to 2×105/mL for a 7-day culture. No toxicity reaction was observed during the culturing period. These results indicated that MWCNTs possessed excellent tissue compatibility.

  20. Distinct electrical effects of multi-walled carbon nanotubes in two composites

    Wang, Leizhi; Wang, Hua; Datta, Timir; Yin, Ming; Tian, Xingyou

    2014-11-01

    The temperature dependent conductivity of multi-walled carbon nanotube film (MWNT) is reported and the different electrical properties of nanotubes in two composites are compared. Due to the disordered structures, our carbon nanotube film displays variable range hopping behavior. While the geometric distributions of carbon nanotubes in the conducting polyaniline (PANI) and insulating polyamide (PA66) are similar, charge carriers transport distinctly. The conductive PANI, following one-dimensional variable range hopping, dominates the electrical properties of MWNT/PANI composites. The effect of MWNTs becomes prominent only at low temperature range. However, the contact junctions composed by adjacent carbon nanotubes, instead of nanotubes themselves or the polymer matrix, determine the electrical properties of MWNT/PA66 composites, showing the fluctuation induced tunneling characteristic.

  1. Comparison of structure and yield of multiwall carbon nanotubes produced by the CVD technique and a water assisted method

    Multiwall carbon nanotubes (MWNTs) were synthesized using chemical vapor deposition (CVD) technique and a water assisted method. Both methods produced MWNTs, which were characterized by SEM, TEM and Raman studies. It was observed that as far as quality is concerned, MWNTs produced by water assisted method are superior as the method does not employ any metal catalyst. However, as far as yield is concerned, CVD is a better method. Multiwall carbon nanotubes produced by water assisted method suffer from the drawback of low yield but have an advantage of production of multiwall carbon nanotubes without using any metal catalyst, at ambient pressure, in an environment friendly manner and using a simple and cost-effective apparatus.

  2. Effect of molecular weight on the properties of polyethylene glycol doped by multiwalled carbon nanotubes

    The differential scanning calorimetry and electrical conductivity methods are used to study the influence of doping multiwalled carbon nanotubes (NTs) on the properties of polyethylene glycol (PEG) of different molecular weights, Mw (PEG-400, PEG-1000, PEG-10000). Dependences of the degree of crystallinity of polymers and the temperature behavior of conductivity on the concentration of NTs are researched. The obtained data indicate a strong influence of the molecular weight of PEG on the spatial distribution of NTs and the electrical conductivity of researched systems.

  3. Highly Enhanced Vapor Sensing of Multiwalled Carbon Nanotube Network Sensors by n-Butylamine Functionalization

    P. Slobodian

    2014-01-01

    Full Text Available The sensing of volatile organic compounds by multiwall carbon nanotube networks of randomly entangled pristine nanotubes or the nanotubes functionalized by n-butylamine, which were deposited on polyurethane supporting electrospinned nonwoven membrane, has been investigated. The results show that the sensing of volatile organic compounds by functionalized nanotubes considerably increases with respect to pristine nanotubes. The increase is highly dependent on used vapor polarity. For the case of highly polar methanol, the functionalized MWCNT network exhibits even more than eightfold higher sensitivity in comparison to the network prepared from pristine nanotubes.

  4. Removal of virus and toxin using heatable multi-walled carbon nanotube web filters

    Hoon-Sik Jang; Sang Koo Jeon; Kwon-Sang Ryu; Seung Hoon Nahm

    2016-01-01

    Many studies have used a carbon nanotube (CNT) filter for pathogen removal and/or inactivation by means of electrochemical or electrochlorination. The large surface area, fine pore size and high electrical and thermal conductivity of CNTs make them suitable and distinct to use for the filtering and removal of pathogens. Here, we grew spin-capable multi-walled CNTs (MWCNTs) and manufactured a web filter using the spun MWCNTs. Botulinum toxin type E light chain (BoT/E-LC) and vaccinia virus (VV...

  5. High luminance organic light-emitting diodes with efficient multi-walled carbon nanotube hole injectors

    Shi, S; Silva, SRP

    2012-01-01

    We report high luminance organic light-emitting diodes by use of acid functionalized multi-walled carbon nanotube (o-MWCNTs) as efficient hole injector electrodes with a simple and solution processable device structure. At only 10 V, the luminance can reach nearly 50,000 cd/m2 with an external quantum efficiency over 2% and a current efficiency greater than 21 cd/A. The investigation of hole-only devices shows that the mechanism for hole injection is changed from injection limited to bulk lim...

  6. Thermal Conductivity of Epoxy Resin Reinforced with Magnesium Oxide Coated Multiwalled Carbon Nanotubes

    Fei-Peng Du; Hao Tang; De-Yong Huang

    2013-01-01

    Magnesium oxide coated multiwalled carbon nanotubes (MgO@MWNT) were fabricated and dispersed into epoxy matrix. The microstructures of MgO@MWNT and epoxy/MgO@MWNT nanocomposites were characterized by TEM and SEM. Electrical resistivity and thermal conductivity of epoxy nanocomposites were investigated with high resistance meter and thermal conductivity meter, respectively. MgO@MWNT has core-shell structure with MgO as shell and nanotube as core, and the thickness of MgO shell is ca. 15 nm. Mg...

  7. Reinforcement of hydrogenated carboxylated nitrile-butadiene rubber by multi-walled carbon nanotubes

    Hydrogenated carboxylated acrylonitrile-butadiene rubber (HXNBR) and multi-walled carbon nanotubes (MWCNT) composites were prepared. The dispersion of MWCNT in HXNBR matrix was evaluated by field emission scanning electron microscopy. HXNBR/MWCNT composite had shorter scorch time and optimum curing time compared with that of unfilled HXNBR. The tensile strength and modulus of HXNBR/MWCNT composites increased with increasing MWCNT content. Mooney-Rivlin equation was used to describe the stress-strain behavior of unfilled HXNBR and the strain amplification factor was taken into account for HXNBR/MWCNT composites. The Mullins effect and dynamic mechanical properties of HXNBR/MWCNT composite were also investigated.

  8. Coherent field emission from a multi-walled carbon nanotube with two open-ended branches

    Interference fringes are obtained in a field-emission microscopy (FEM) study of a multi-walled carbon nanotube (MWCNT) with two open-ended branches. The FEM pattern, which is composed of three parallel streaks, can be interpreted by using classical Young's double-slit interference with the ends of the two MWCNT branches treated as two secondary sources of the electron wave. The origin of the coherency of the electron beams from the two branches is discussed on the basis of the quantitative analysis of the FEM pattern. The result suggests a new approach to obtaining a coherent electron source. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  9. Direct evaluation of ballistic phonon transport in a multi-walled carbon nanotube

    Phonon confinement and in situ thermal conductance measurements in an individual multi-walled carbon nanotube (MWNT) are reported. Focused ion beam (FIB) irradiation was used to successively shorten a 4.8 μm long MWNT, eventually yielding a 0.3 μm long MWNT. After the first FIB irradiation, a 41% reduction in conductance was achieved, compared with that of the pristine MWNT. This was because the contributions from phonons with long free paths were excluded by scattering at FIB-induced defects. Phonon transport in linked multiple-length nanotubes was also investigated

  10. Fabrication of multi-walled carbon nanotubes-aluminum matrix composite by powder metallurgy technique

    Bunakov, N. A.; Kozlov, D. V.; Golovanov, V. N.; Klimov, E. S.; Grebchuk, E. E.; Efimov, M. S.; Kostishko, B. B.

    We report on fabrication of an aluminum matrix composite containing multi-walled carbon nanotubes (MWCNTs) produced by MOCVD method and functionalized via acid treatment by a H2SO4/HNO3 mixture. Specimens were prepared by spark plasma sintering (SPS) of the aluminum powder with different amounts of functionalized MWCNTs (FMWCNTs) in the range of 0.1-1 wt.%. We studied the effect of FMWCNTs amount on microstructure and mechanical properties of composites. It is shown that functionalization allows homogeneous dispersing of the MWCNTs in Al powder. The maximal increase in micro-hardness and tensile strength is registered at 0.1 wt.%.

  11. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed

  12. Synthesis and magnetic properties of multiwalled carbon nanotubes decorated with magnetite nanoparticles

    Pistone, A., E-mail: pistone@unime.it [Department of Electronic Engineering, Chemistry and Industrial Engineering, University of Messina, Messina I-98166 (Italy); Iannazzo, D.; Fazio, M. [Department of Electronic Engineering, Chemistry and Industrial Engineering, University of Messina, Messina I-98166 (Italy); Celegato, F.; Barrera, G.; Tiberto, P. [INRIM Electromagnetism Division, Torino (Italy); Giordano, A.; Azzerboni, B.; Galvagno, S. [Department of Electronic Engineering, Chemistry and Industrial Engineering, University of Messina, Messina I-98166 (Italy)

    2014-02-15

    Magnetite particles with nanoscale sizes were deposited along multiwalled carbon nanotubes (MWCNT) through a simple, effective and reproducible chemical route. The structure, morphology and magnetic properties of the hybrid materials were characterized by XRD, SEM, TEM, EDX, VSM. The characterization results show that the surface of nanotubes was loaded with iron oxides nanoclusters and each nanocluster is composed by several nanocrystals with a mean diameter of 10 nm. The experimental magnetic hysteretic behavior has been also studied by means of the Preisach model and a good agreement between experimental data and numerical computations was found.

  13. Multiwalled carbon nanotubes for dielectric sensing of biological systems: An effective treatment of polarization

    Picaud, F.; Girardet, C.

    We determine the efficiency of semi-conducting multiwalled carbon nanotubes in resonator configuration acting as sensors of biological systems. The resonance frequency shifts due to the dielectric changes of the resonator upon adsorption of highly idealized micelles schematized by a set of concentric shells of polarizable centers surrounded by a water shell to mimic the solvent are calculated on the basis of an effective polarizability distribution in the tube and the sensed system. Cylindrical and spherical geometries including different sizes are considered for the micelles to show that size and geometry selectivity could be reached with such an approach.

  14. Novel fabrication of silica nanotubes using multi-walled carbon nanotubes as template

    Zhi-Hua Yin; Xiang Liu; Zhong-Xing Su

    2010-08-01

    Silica nanotubes were synthesized using multi-walled carbon nanotubes (MWCNTs) as template. The as-obtained samples were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscope (FE–SEM) and photoluminescent (PL) spectroscopy. The results indicate that the thickness of the outer walls is about 10 nm and the inner diameter is completely dependent on the size of MWCNTs. The as-fabricated silica nanotubes emit a strong violet light under excitation of 250 nm.

  15. Time-resolved laser-induced incandescence from multiwalled carbon nanotubes in air

    Mitrani, J. M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA; Shneider, M. N. [Department of Mechanical Engineering, Princeton University, Princeton, New Jersey 08544, USA

    2015-01-26

    We observed temporal laser-induced incandescence (LII) signals from multiwalled carbon nanotubes(MWCNTs) suspended in ambient air. Unlike previous LII experiments with soot particles, which showed that primary particles with larger diameters cool at slower timescales relative to smaller particles, we observed that thicker MWCNTs with larger outer diameters (ODs) cool at faster timescales relative to thinner MWCNTs with smaller ODs. We suggested a simple explanation of this effect, based on the solution of one-dimensional nonstationary heat conduction equation for the initial non-uniform heating of MWCNTs with ODs greater than the skin depth.

  16. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    Yang Jun; Yao Zhiwen [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Tang Changyu [Department of Polymer Science and Materials, Sichuan University (China); Darvell, B.W. [Dental Materials Science, Faculty of Dentistry, University of Hong Kong (Hong Kong); Zhang Hualin; Pan Lingzhan; Liu Jingsong [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Chen Zhiqing, E-mail: yangj0710@gmail.com [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China)

    2009-07-30

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  17. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal, E-mail: zainabh@petronas.com.my [Centre of Innovative Nanostructures and Nanodevices, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  18. Laser Stimulation the Electroconductivity of Composite Layers with Multiwalled Carbon Nanotubes

    Galperin V.A.

    2013-09-01

    Full Text Available Electroconductivity laser stimulation (irradiation of composite layers based on carboxymethyl cellulose (CMC and multiwalled carbon nanotubes (MWCNT has been researched. The layers were deposited on the following substrates: flexible such as polyimide, polyester, aluminum foil paper, cotton fabric and shop paper (~80 g/m2]; hard substrates such as Si/SiΟ2 and cover glass. The conductivity of layers with thickness 0.5 - 10 µm was improved more on 500 % /(W/cm2 after laser stimulation (wavelength 970 nm, emission specific power Ps~0.05 - 1 W/cm2, concentration C~0.05 wt.% MWCNT.

  19. Effects of phonon dimensionality in the specific heat of multiwall carbon nanotubes at low temperatures

    Jorge, Guillermo A; Bekeris, V; Acha, C [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN-UBA, Pab. 1, Ciudad Universitaria (1428), Buenos Aires (Argentina); Escobar, M M; Goyanes, S [Laboratorio de Polimeros y Materiales Compuestos, Departamento de Fisica, FCEyN-UBA, Pab. 1, Ciudad Universitaria (1428), Buenos Aires (Argentina); Zilli, D; Cukierman, A L [PINMATE, Departamento de Industrias, FCEyN-UBA, Pab. Industrias, Ciudad Universitaria (1428), Buenos Aires (Argentina); Candal, R J, E-mail: gjorge@df.uba.a [Instituto de Fisicoquimica de Materiales, Ambiente y EnergIa, CONICET-UBA, Ciudad Universitaria (1428) Buenos Aires (Argentina)

    2009-05-01

    We have measured the specific heat at constant pressure, C{sub p}, of three different samples of multiwall carbon nanotubes (MWNT). For all samples, C{sub p} departs from a graphitic behavior at T < 120 K. C{sub p} measurements show a temperature threshold from a linear regime for intermediate temperature to a higher-order power law for low temperatures. Moreover, it was found that this crossover only depends on the internal structure of the individual MWNT and not on the spatial order of the MWNT within a bundle.

  20. Multiband microwave absorption films based on defective multiwalled carbon nanotubes added carbonyl iron/acrylic resin

    Li, Yong; Chen, Changxin; Pan, Xiaoyan; Ni, Yuwei; Zhang, Song; Huang, Jie; Chen, Da; Zhang, Yafei

    2009-05-01

    Defective multiwalled carbon nanotubes (MWCNTs) were introduced to the carbonyl iron (CI) based composites to improve its microwave absorption by a simple ultrasonic mixing process. The electromagnetic parameters were measured in the 2-18 GHz range. Microwave absorption of CI based composites with 2 mm in thickness was evidently enhanced by adding as little as 1.0 wt% defective MWCNTs with two well separated absorption peaks exceeding -20 dB, as compared with that of pure CI based and defective MWCNTs composites. The enhancement mechanism is thought due to the interaction and better electromagnetic match between defective MWCNTs and ferromagnetic CI particles.

  1. Facile route to multi-walled carbon nanotubes under ambient conditions

    Ha, Hyunchul; Jeong, Soo-Hwan [Kyungpook National University, Daegu (Korea, Republic of)

    2016-02-15

    A facile and practical route is demonstrated to prepare multi-walled carbon nanotubes (MWCNTs) by a sonochemical method. By applying ultrasonic irradiation to the mixture of ferrocene and xylene with small amount of water, crystalline MWCNTs were selectively synthesized under ambient conditions, allowing MWCNTs with diameter of 25-40 nm to be obtained. A control experiment revealed that a small amount of water was essential for producing MWCNTs. The analysis of Raman spectra of MWCNTs showed that the intensity of the D-band relative to the G-band was 0.98, indicating relatively good crystallinity of these MWCNTs. This result was consistent with that of TEM observation.

  2. Synthesis of multi-walled carbon nanotubes and their application in resin based nanocomposites

    Multi-walled carbon nanotubes (MWCNTs) were synthesized by catalytic decomposition of hydrocarbon gas using chemical vapor deposition method. Synthesis was done at different growth temperatures and catalyst ratios. These MWCNTs were dispersed in epoxy resin (E-51) and their effect on mechanical strength of epoxy nanocomposites was studied. Increase in the mechanical strength of epoxy was observed with the addition of CNTs. The surface characterization was done by using optical microscope and scanning electron microscope (SEM). Mechanical properties were determined by the general tensile strength testing method.

  3. Electrochemical oxidation of some basic alcohols on multiwalled carbon nanotube–platinum composites

    Minsoo Koo; Jong-Seong Bae; Hyun-Chul Kim; Dae-Geun Nam; Chang Hyun Ko; Jeong Hyun Yeum; Weontae Oh

    2012-08-01

    Some composites of multiwalled carbon nanotubes, which were chemically treated in acidic and/or hydrogen peroxide solution, and platinum nanoparticles were prepared by the simple reduction in glycerol solution. Carboxylated and/or hydroxyl MWNTs were structurally analysed using X-ray photoelectron spectroscopy. In addition, the MWNT–Pt composites were characterized by XRD and TEM in detail. The electrochemical oxidation of some basic alcohols, which was catalyzed by the MWNT–Pt composites, was analysed by cyclic voltammetry. Their catalytic activities were studied with cyclic voltammograms of alcohols.

  4. Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

    Penwisa Pisitsak; Rathanawan Magaraphan; Sadhan C. Jana

    2012-01-01

    A thermotropic liquid crystalline polymer (LCP) was blended with polycarbonate (PC) and multiwalled carbon nanotube (CNT) with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950) and Vectra V400P (V400P). The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by m...

  5. Dynamic characteristics of multi-walled carbon nanotubes under a transverse magnetic field

    S Li; H J Xie; X Wang

    2011-02-01

    This paper reports the results of an investigation into the effect of transverse magnetic fields on dynamic characteristics of multi-walled carbon nanotubes (MWNTs). Couple dynamic equations of MWNTs subjected to a transverse magnetic field are derived and solved by considering the Lorentz magnetic forces induced by a transverse magnetic field exerted on MWCNTs. Results show that the transverse magnetic field exerted on MWNTs makes the lowest frequency of the MWNTs nonlinearly decrease and the highest frequency, changeless. When the strength of applied transverse magnetic fields is larger than a given value the two walls of MWNTs appear in the radial and axial coaxial vibration phenomena.

  6. Viscoelastic behavior of multiwalled carbon nanotubes into phenolic resin

    Botelho, Edson Cocchieri; Costa, Michelle Leali; Braga, Carlos Isidoro, E-mail: ebotelho@feg.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Dept. de Materiais e Tecnologia; Burkhart, Thomas [Institut fuer Verbundwerkstoffe GmbH, Kaiserslautern, (Germany); Lauke, Bernd [Leibniz-Institut fuer Polymerforschung, Dresden (Germany)

    2013-11-01

    Nanostructured polymer composites have opened up new perspectives for multi-functional materials. In particular, carbon nanotubes (CNTs) have the potential applications in order to improve mechanical and electrical performance in composites with aerospace application. This study focuses on the viscoelastic evaluation of phenolic resin reinforced carbon nanotubes, processed by using two techniques: aqueous-surfactant solution and three roll calender (TRC) process. According to our results a relative small amount of CNTs in a phenolic resin matrix is capable of enhancing the viscoelastic properties significantly and to modify the thermal stability. Also has been observed that when is used TRC process, the incorporation and distribution of CNT into phenolic resin is more effective when compared with aqueous solution dispersion process. (author)

  7. Viscoelastic behavior of multiwalled carbon nanotubes into phenolic resin

    Nanostructured polymer composites have opened up new perspectives for multi-functional materials. In particular, carbon nanotubes (CNTs) have the potential applications in order to improve mechanical and electrical performance in composites with aerospace application. This study focuses on the viscoelastic evaluation of phenolic resin reinforced carbon nanotubes, processed by using two techniques: aqueous-surfactant solution and three roll calender (TRC) process. According to our results a relative small amount of CNTs in a phenolic resin matrix is capable of enhancing the viscoelastic properties significantly and to modify the thermal stability. Also has been observed that when is used TRC process, the incorporation and distribution of CNT into phenolic resin is more effective when compared with aqueous solution dispersion process. (author)

  8. Grafting of Multiwalled Carbon Nanotubes with Chicken Feather Keratin

    Yoxkin Estévez-Martínez

    2013-01-01

    Full Text Available Keratin, obtained from chicken feathers, was grafted on the surface of commercially available carbon nanotubes. The original procedure developed allows a covalent interaction between some specific chemical groups characteristic of the keratin, with some functional groups introduced on purpose on the surface of the nanotubes, as revealed by infrared and Raman spectroscopies, which also allowed to determine structural changes introduced during the process, such as crystallinity, which lead to changes in other properties, as well.

  9. Serotonin sensor based on a glassy carbon electrode modified with multiwalled carbon nanotubes, chitosan and poly(p-aminobenzenesulfonate)

    A glassy carbon electrode was modified with a nanocomposite prepared from poly(p-aminobenzene sulfonic acid), multi-walled carbon nanotubes and chitosan to obtain a differential pulse voltammetric sensor for serotonin that is remarkably stable and displays enhanced current response. Its peak current (at 0.38 V vs. Ag/AgCl) varied linearly with the concentration of serotonin in the 0.1–100 μM range, and the detection limit is 80 nM (at an S/N of 3). The sensor was successfully applied to the determination of serotonin in (spiked) human blood serum. (author)

  10. In vitro studies of multiwalled carbon nanotube/ultrahigh molecular weight polyethylene nanocomposites with osteoblast-like MG63 cells.

    Reis, J.; S. Kanagaraj; Fonseca, A.; Mathew, M. T.; F. Capela-Silva; J. Potes; Pereira, A.; Oliveira, M. S. A.; Simões, J A

    2010-01-01

    Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwalled carbon nanotubes in biomaterials contacting with bone. However, carbon nanotubes are also controversial in regards to effects exerted on living organisms. Carbon nanotubes can be used to improve the tribological properties of polymer/composite materials. Ultrahigh molecular weight polyethylene (UHMWPE) is a polym...

  11. In vitro studies of multiwalled carbon nanotube/ultrahigh molecular weight polyethylene nanocomposites with osteoblast-like MG63 cells

    Reis, Joana; Kanagaraj, Subramani; Capela Silva, Fernando; Pereira, Alfredo; Potes, José; Mathew, MT; Simões, José

    2010-01-01

    Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwalled carbon nanotubes in biomaterials contacting with bone. However, carbon nanotubes are also controversial in regards to effects exerted on living organisms. Carbon nanotubes can be used to improve the tribological properties of polymer/composite materials. Ultrahigh molecular weight polyethylene (UHMWPE) is a polym...

  12. Mechanical properties of multi-walled carbon nanotube/epoxy polysulfide nanocomposite

    Highlights: ► Preparation of epoxy polysulfide nanocomposite. ► Multi-walled carbon nanotubes have been modified and dispersed in epoxy polysulfide matrix. ► Mechanical properties of MWNT/epoxy polysulfide have been studied. - Abstract: In this research, multi-walled carbon nanotubes (MWCNTs) were modified by acid functionalization (H2SO4:HNO3 = 1:3 by volume) and then mechanical properties of reinforced epoxy polysulfide resin by the both pure and treated MWNTs have been evaluated. For achieving this goal, different weight percentages of pure and treated MWCNT (0.1–0.3 wt%) were dispersed in the epoxy polysulfide resin separately and then mixed with curing agent. Experimental results have shown significant difference between acid treated and untreated MWCNTs in mechanical properties of epoxy polysulfide nanocomposites. In nanocomposite with 0.1–0.3% acid treated MWCNTs we observed increase of Young’s modulus from 458 to 723 MPa, tensile strength from 5.29 to 8.83 MPa and fracture strain from 0.16% to 0.25%. For understanding the structure and morphology of nanocomposite, the dispersion states were studied using scanning electron microscopy (SEM) and field emission electron microscopy (FESEM). The results showed better dispersion of modified carbon nanotube than unmodified in polymeric matrix

  13. Interlaminar Fracture Toughness of CFRP Laminates Incorporating Multi-Walled Carbon Nanotubes

    Elisa Borowski

    2015-06-01

    Full Text Available Carbon fiber reinforced polymer (CFRP laminates exhibit limited fracture toughness due to characteristic interlaminar fiber-matrix cracking and delamination. In this article, we demonstrate that the fracture toughness of CFRP laminates can be improved by the addition of multi-walled carbon nanotubes (MWCNTs. Experimental investigations and numerical modeling were performed to determine the effects of using MWCNTs in CFRP laminates. The CFRP specimens were produced using an epoxy nanocomposite matrix reinforced with carboxyl functionalized multi-walled carbon nanotubes (COOH–MWCNTs. Four MWCNTs contents of 0.0%, 0.5%, 1.0%, and 1.5% per weight of the epoxy resin/hardener mixture were examined. Double cantilever beam (DCB tests were performed to determine the mode I interlaminar fracture toughness of the unidirectional CFRP composites. This composite material property was quantified using the critical energy release rate, GIC. The experimental results show a 25%, 20%, and 17% increase in the maximum interlaminar fracture toughness of the CFRP composites with the addition of 0.5, 1.0, and 1.5 wt% MWCNTs, respectively. Microstructural investigations using Fourier transform infrared (FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS verify that chemical reactions took place between the COOH–MWCNTs and the epoxy resin, supporting the improvements experimentally observed in the interlaminar fracture toughness of the CFRP specimens containing MWCNTs. Finite element (FE simulations show good agreement with the experimental results and confirm the significant effect of MWCNTs on the interlaminar fracture toughness of CFRP.

  14. Interactions of 14C-labeled multi-walled carbon nanotubes with soil minerals in water

    Carbon nanotubes are often modified to be stable in the aqueous phase by adding extensive hydrophilic surface functional groups. The stability of such CNTs in water with soil or sediment is one critical factor controlling their environmental fate. We conducted a series of experiments to quantitatively assess the association between water dispersed multi-walled carbon nanotubes (MWCNTs) and three soil minerals (kaolinite, smectite, or shale) in aqueous solution under different sodium concentrations. 14C-labeling was used in these experiments to unambiguously quantify MWCNTs. The results showed that increasing ionic strength strongly promoted the removal of MWCNTs from aqueous phase. The removal tendency is inversely correlated with the soil minerals’ surface potential and directly correlated with their hydrophobicity. This removal can be interpreted by the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theory especially for kaolinite and smectite. Shale, which contains large and insoluble organic materials, sorbed MWCNTs the most strongly. - Graphical abstract: The stability of multi-walled carbon nanotubes in an aqueous system containing kaolinite, smectite or shale as model soil minerals is investigated using the 14C-labeling technique. Highlights: ► The interactions between MWCNTs and kaolinite, smectite, or shale were probed. ► Surface potential and hydrophobicity of the particles governs their interactions. ► EDLVO can be used to interpret the interactions. ► Insoluble organic materials in shale strongly sorb MWCNTs.

  15. Decorating multi-walled carbon nanotubes with nickel nanoparticles for selective hydrogenation of citral

    The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). Due to the strong interaction between Ni2+ and -COOH, PAA-g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated with Ni nanoparticles (Ni-MWNTs) for α, β-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC). - Abstract: Nickel nanoparticles decorated multi-walled carbon nanotubes (Ni-MWNTs) nanocomposites were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). These nanocomposites possessed excellent catalytic activity and selectivity for hydrogenation of citral.

  16. Production of palladium nanoparticles supported on multiwalled carbon nanotubes by gamma irradiation

    Palladium nanoparticles were produced and supported on multiwalled carbon nanotubes (MWCNT) by gamma irradiation. A solution with a specific ratio of 2:1 of water-isopropanol was prepared and mixed with palladium chloride and the surfactant sodium dodecyl sulfate (SDS). The gamma radiolysis of water ultimately produces Pd metallic particles that serve as nucleation seeds. Isopropanol is used as an ion scavenger to balance the reaction, and the coalescence of the metal nanoparticles was controlled by the addition of SDS as a stabilizer. The size and distribution of nanoparticles on the carbon nanotubes (CNT) were studied at different surfactant concentrations and radiation doses. SEM, STEM and XPS were used for morphological, chemical and structural characterization of the nanostructure. Nanoparticles obtained for doses between 10 and 40 kGy, ranged in size 5-30 nm. The smaller nanoparticles were obtained at the higher doses and vice versa. Histograms of particle size distributions at different doses are presented. - Highlights: → Palladium nanoparticles deposited on multiwalled carbon nanotubes by gamma irradiation. → Dependence of size and distribution of the nanoparticles on dose and surfactant evaluated. → Interaction of Pd and CNTs explained by the formation of Pd-O on the surface of the CNTs. → Distribution of palladium particles with an average size of 5 nm obtained at 40 kGy and 0.07 M SDS.

  17. Enhanced wear properties of hybrid PTFE/cotton fabric composites filled with functionalized multi-walled carbon nanotubes

    Multi-walled carbon nanotubes (MWCNTs) are important nano-fillers in polymer composites. In this paper, enhanced wear properties of nanocomposites were achieved through introducing functionalized multi-walled carbon nanotubes into hybrid PTFE/cotton fabric composite. Results of characterizations, including Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM), revealed that MWCNTs were successfully functionalized and the modification led to an improvement in the dispersion of MWCNTs. The reasons for the enhanced tribological properties of hybrid PTFE/cotton fabric composite were also discussed based on the results of characterizations.

  18. Tunneling phenomena in aligned multi-walled carbon nanotube sheets: conductivity and Raman correlations

    We performed simultaneous Raman spectroscopy and electrical conductivity measurements on self-standing aligned multi-walled carbon nanotubes sheets at varying inter-tube distances. A sapphire anvil cell is used here to modulate the inter-tube distance and promote the subsequent electronic tunneling phenomena. We observe a singular correlation between the intensity of the so called defect bands of carbon materials and their conductivity. This indicates that the conditions of the resonant processes that originate these bands are modified by the tunneling phenomena. Such an issue has never been reported before and has potential technological applications. Additionally, the provided AFM images evidence the debundling of the carbon nanotubes that had been described to occur after small compression. (paper)

  19. The effects of contacts and ambipolar electrical transport in nitrogen doped multiwall carbon nanotubes

    Zhang, W J; Zhang, J Y; Li, P J; Shen, X; Zhang, Q F; Wu, J L [Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China)], E-mail: jlwu@pku.edu.cn

    2008-02-27

    The electrical transport properties of pristine single wall carbon nanotubes (SWCNTs) and lower nitrogen content doped multiwall carbon nanotubes (MWCNTs) (lower than in the experiments of Xiao et al (2005 J. Am. Chem. Soc. 127 8614)) in contact with Au and Pt were studied. Compared with pristine SWCNTs, the Fermi level of the lower nitrogen content doped MWCNTs also moved to the valence band edge with the contact metal's work function increasing. In contrast to Derycke et al' s results (2002 Appl. Phys. Lett. 80 2773), the lower nitrogen content doped MWCNTs exhibited ambipolar behavior, and increasing the doping level led to a reduction of the Schottky barrier height of electrons. Consistent with theoretical calculations, the results support the opinion that the degree of Fermi level pinning is minor for doped carbon nanotubes.

  20. Decorating multiwalled carbon nanotubes with zinc oxide nano-crystallines through hydrothermal growth process

    LI ChenSha; QIAO YingJie; LI YuMing

    2012-01-01

    Multiwalled-carbon nanotubes coated with nano-crystalline zinc oxide (ZnO) was prepared by in situ growth of nano zinc oxide on the surfaces of carbon nanotubes through hydrothermal method.X-ray diffraction,transmission electron microscopy and scanning electron microscopy analysis techniques were used to characterize the samples.It was observed that a layer of nano-crystalline ZnO with the wurtzite hexagonal crystal structure was uniformly coated on the nanotube surfaces with good adhesion,which resulted in the formation of a novel ZnO-nanotube nano composite.In this work,the carbon nanotubes decorated by metal oxide nanoparticles were synthesized by a simple chemical-solution route which is suitable for the large-scale production with low cost.

  1. A novel silica-coated multiwall carbon nanotube with CdTe quantum dots nanocomposite

    Fei, Qiang; Xiao, Dehai; Zhang, Zhiquan; Huan, Yanfu; Feng, Guodong

    2009-10-01

    A novel silica-coated multiwall carbon nanotube (MWNTs) with CdTe quantum dots nanocomposite was synthesized in this paper. Here, we show the in situ growth of crystalline CdTe quantum dots on the surfaces of oxidized MWNTs. The approach proposed herein differs from previous attempts to synthesize nanotube assemblies in that we mix the oxidized MWNTs into CdCl 2 solution of CdTe nanocrystals synthesized in aqueous solution. Reinforced the QD-MWNTs heterostructures with silica coating, this method is not invasive and does not introduce defects to the structure of carbon nanotubes (CNTs), and it ensures high stability in a range of organic solvents. Furthermore, a narrow SiO 2 layer on the MWNT-CdTe heterostructures can eliminate the biological toxicity of quantum dots and carbon nanotubes. This is not only a breakthrough in the synthesis of one-dimensional nanostructures, but also taking new elements into bio-nanotechnology.

  2. Dielectric constants of multiwall carbon nanotubes from direct current to microwave frequencies.

    Wang, Y C; Lue, J T; Pauw, K F

    2009-03-01

    A cylindrical rod constructed from a uniform mixture of multiwall carbon nanotubes and alumina powders dissolved in paraffin was inserted in the center of a radio frequency cavity. The real and imaginary dielectric constants of carbon tubes at various frequencies were measured, respectively, from the resonant frequencies and the quality factors, by a resistance-inductance-cacitance (RLC) meter and a microwave network analyzer. The dielectric rod benefits the protection of the sample from adsorbing moisture and preventing the rod from filling with air, thus making accurate measurments. A tunable probe specifically designed for the field pattern of a TM010 mode is delineated to improve the microwave coupling of the dielectric microwave resonator. This refined design is expected to facilitate the measurement yielding a significant manner. The real and imaginary parts of the dielectric constant of carbon nanotubes increase and decrease, respectively as frequencies increase satisfactorily in complying with the description from the free electron Drude model. PMID:19435033

  3. Fabrication of micro pillars using multiwall carbon nanotubes/polymer nanocomposites

    This research presents a new approach to fabricate polymer/carbon nanotubes (CNT) nanocomposites. Multiwall carbon nanotubes with 6–9 nm diameter and 1.5 µm length are used. Polydimethysolixane (PDMS), acetone and polyethylene oxide (PEO) are used as polymer matrix, solvent and dispersant, respectively. The research work is divided into two stages: dispersion of CNT and preparation of PDMS/CNT nanocomposite. A new method is used to disperse the carbon nanotubes into acetone with the help of PEO dispersant. The optimum dispersant to the CNT weight ratio and sonication time for obtaining well-dispersed CNT are obtained and found to be 1.0 and 4.5 h, respectively. Micro pillars made of nanocomposites containing different CNT in the PDMS matrix are produced. The surface roughness and the fracture of nanocomposite are also investigated. (paper)

  4. Influence of Zn ion implantation on structures and field emission properties of multi-walled carbon nanotube arrays

    2010-01-01

    The structures and field emission properties of multi-walled carbon nanotube arrays implanted with Zn+ by MEVVA ion implanter have been investigated.The results revealed that Zn+implantation induced structural damage and that the top of carbon nanotubes with multi-layered graphite structure were transformed into carbon nanowires with amorphous structure.Meanwhile,C:Zn solid solution was synthesized after Zn+ implantation.The turn-on field and threshold field were 0.80 and 1.31 V/μm,respectively for original multi-walled carbon nanotube arrays and were reduced to 0.66 and 1.04 V/μm due to the synthesis of C and Zn composite,in which the work function was reduced after low doses of Zn+implantation.It is indicated that low doses of Zn+implantation can improve field emission performance of multi-walled carbon nanotube arrays.Otherwise,high doses of Zn+implantation can reduce field emission properties of multi-walled carbon nanotube arrays,because radiation damage reduces the electric field enhancement factor.

  5. VRH investigation of polyaniline–multiwalled carbon nanotube nanocomposite network

    Amin Imani; Gholamali Farzi

    2015-08-01

    Polyaniline and polyaniline/multi-walled carbon nanotube (PAni/MWCNT) nanocomposites were synthesized by in-situ chemical oxidative polymerization of aniline. Ammonium peroxydisulphate and p-toluenesulphonic acid were used as an initiator and surfactant dopant, respectively. The molar ratio of monomer unit to initiator and dopant was 1:1:1 and the percentage of MWCNT in PAni varied from 1 to 10 wt%. The structure of the resulting nanocomposite was characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The effects of MWCNT concentration on the electrical properties of the resulting nanocomposites were studied at temperatures between 90 and 300 K. Conductivity increases with the combination of MWCNT in the PAni environment. The strong coupling between the MWCNT and the PAni chains enhances the average localization length and hence conductivity increases for the nanocomposites.

  6. Characterization of Genotoxic Response to 15 Multiwalled Carbon Nanotubes with Variable Physicochemical Properties Including Surface Functionalizations in the FE1-Muta(TM) Mouse Lung Epithelial Cell Line

    Jackson, Petra; Kling, Kirsten; Jensen, Keld Alstrup;

    2015-01-01

    Carbon nanotubes vary greatly in physicochemical properties. We compared cytotoxic and genotoxic response to 15 multiwalled carbon nanotubes (MWCNT) with varying physicochemical properties to identify drivers of toxic responses. The studied MWCNT included OECD Working Party on Manufactured Nanoma...

  7. Direct laser interference patterning of multi-walled carbon nanotube-based transparent conductive coatings

    Topographical structures were created on the surface of multi-walled carbon nanotube-based coatings deposited on borosilicate glass using the direct laser interference patterning (DLIP) technique. Films made by multi-walled carbon nanotubes (MWNTs) dispersed in antimony-doped tin oxide (ATO) matrix and networks of MWNTs with both low and high adherence to the substrates were irradiated with one single laser pulse. Due to the high absorption coefficient of ATO, the film was completely removed at the interference maxima positions leading to periodic arrays of high quality on macroscopic areas. Additionally, increase of the laser fluence has produced wider ablated regions. Irradiation of high adherent networks of MWNTs produced a periodic porous structure, what has been attributed to the presence of adherence promoters in the film. On the other hand, MWNT networks with low adhesion to the substrate were strongly removed at the interference maxima positions. In this case, however, the fabricated periodic structures presented several defects that result from the poor adherence of the film to the substrate

  8. Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes

    Huang, Zhenlong; Gao, Min; Yan, Zhuocheng; Pan, Taisong; Liao, Feiyi; Lin, Yuan

    2016-05-01

    Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors.Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08791k

  9. Electrochemical performance of Si-multiwall carbon nanotube nanocomposite anode synthesized by thermal plasma

    Na, Ye-Seul; Yoo, Hyeonseok; Kim, Tae-Hee; Choi, Jinsub; Lee, Wan In; Choi, Sooseok, E-mail: sooseok@jejunu.ac.kr; Park, Dong-Wha, E-mail: dwpark@inha.ac.kr

    2015-07-31

    Lithium-ion (Li-ion) batteries are widely used in electric devices and vehicles. Silicon is a promising material for the anode of Li-ion battery due to high theoretical specific capacity. However, it shows large volume changes during charge–discharge cycles leading to the pulverization of electrode. In order to improve such disadvantage, a multiwall carbon nanotube (MWCNT) has been used with silicon as composite material. In this work, Si-MWCNT nanocomposite was prepared in thermal plasma by attaching silicon nanoparticles to MWCNT column. Electrochemical tests for raw materials and synthesized nanocomposites were carried out. The discharge capacities of silicon, MWCNT, synthesized nanocomposites collected from a reaction tube, and a chamber were 4000, 310, 200, and 1447 mAh/g, respectively. - Highlights: • Si-Multiwall carbon nanotube nanocomposite was synthesized by thermal plasma. • The effect on the collection position of product after experiment was examined. • Cycle performance of electrodes was measured. • Product collected from chamber showed good electrochemical performance.

  10. Latex stage blending of multiwalled carbon nanotube in carboxylated acrylonitrile butadiene rubber: Mechanical and electrical properties

    Highlights: ► MWCNT can act as a reinforcing filler in XNBR at very low concentration. ► SEM and XRD analysis confirm uniform distribution of nanotube in the matrix. ► Mechanical properties showed considerable improvement. ► Thermal stability of the composite is marginally improved. -- Abstract: Multiwalled carbon nanotube (MWCNT) was dispersed in sodium dodecyl benzene sulphonate (SDBS) by sonication. The dispersed MWCNT (0.05–0.3 gm) was incorporated in carboxylated acrylonitrile butadiene rubber (XNBR) latex. Mechanical, electrical and thermal properties of these composites were studied. Mechanical properties of the composites increased up to an optimum concentration and then decreased. Dielectric properties of the composites were studied in the S band (frequency range 2–4 GHz) by Cavity Perturbation method. Direct current (DC) electrical conductivity shows a percolation behaviour and conductivity increased by about 10 orders of magnitude. Thermal studies were conducted using Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA). As expected with the very small concentration of multiwalled carbon nanotube, glass transition temperature (Tg) and thermal stability of the composite showed a marginal increase. Composites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscope (SEM) analysis.

  11. Iridium-decorated multiwall carbon nanotubes and its catalytic activity with Shell 405 in hydrazine decomposition

    Prasad, V.; Vasanthkumar, M. S., E-mail: vasanth.physics@gmail.com [Indian Institute of Science, Department of Physics (India)

    2015-10-15

    Iridium-functionalized multiwalled carbon nanotubes (Ir-MWNT) are the future catalyst support material for hydrazine fuel decomposition. The present work demonstrates decoration of iridium particle on iron-encapsulated multiwalled carbon nanotubes (MWNT) by wet impregnation method in the absence of any stabilizer. Electron microscopy studies reveal the coated iridium particle size in the range of 5–10 nm. Elemental analysis by energy dispersive X-ray diffraction confirms 21 wt% of Ir coated over MWNT. X-ray photoelectron spectroscopy (XPS) shows 4f{sub 5/2} and 4f{sub 7/2} lines of iridium and confirms the metallic nature. The catalytic activity of Ir-MWNT/Shell 405 combination is performed in 1 N hydrazine micro-thrusters. The thruster performance shows increase in chamber pressure and decrease in chamber temperature when compared to Shell 405 alone. This enhanced performance is due to high thermal conducting nature of MWNTs and the presence of Ir active sites over MWNTs.

  12. Synthesis of gas barrier starch by dispersion of functionalized multiwalled carbon nanotubes.

    Swain, Sarat K; Pradhan, Ajaya K; Sahu, Hari S

    2013-04-15

    Nanocomposite films were prepared successfully by simple solution casting method from plasticized starch/functionalized multiwalled carbon nanotubes (PS/f-MWCNTs). The interaction of starch with functionalized multiwalled carbon nanotube (f-MWCNT) was evidenced by ultraviolet-visible (UV-vis) spectroscopy and Fourier transforms infrared (FTIR) spectroscopy. The morphological and thermal properties of the composite films were investigated using scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The electrical conductivity of the composites was increased significantly by sixteen times, from 0.1×10(-9) to 1.6×10(-9) S/cm. This reveals better dispersion of f-MWCNT with low concentration of f-MWCNT. The oxygen permeability of the composites was reduced by half as compared to virgin PS. This indicates better dispersion of f-MWCNT in PS matrix due to formation of strong hydrogen bonding with PS matrix. PMID:23544588

  13. Gas sensing properties of multiwall carbon nanotubes decorated with Rh nanoparticles

    Leghrib, Radouane; Demoisson, Frédéric; Claessens, Nicolas; Reniers, François; Llobet, Eduard

    2016-01-01

    In the present work, multiwalled carbon nanotubes were decorated with rhodium nanoparticles using a colloidal solution in the post-discharge of an RF atmospheric plasma of argon (Ar) or argon/oxygen (Ar:O$_2$). The properties of these hybrid materials towards the room temperature detection of NO$_2$, C$_2$H$_4$, CO, C$_6$H$_6$ and moisture were investigated and discussed in view of compositional and morphological studies. It was found that the presence of oxygen in the plasma treatment is essential to significantly enhance the gas response of Rh-decorated multiwalled carbon nanotubes and to avoid response saturation even at low gas/vapor concentrations. These desirable effects are attributed to the presence of oxygen during the CNT plasma treatment since oxygenated vacancies act both as active adsorption sites for gases and as anchoring sites for Rh nanoparticles (the presence of Rh nanoclusters is nearly doubled in Ar-O$_2$ treated samples as compared to Ar treated samples). The oxygen treatment also makes e...

  14. Comparative study of electrochemical capacitance of multi-walled carbon nanotubes before and after chopping

    In the work, short multi-walled carbon nanotubes (S-CNTs) were synthesized by chopping conventional μm-long multi-walled carbon nanotubes (L-CNTs) under ultrasonication in H2SO4/HNO3 mixed acids. A comparative electrochemical investigation performed in 6 M KOH solution demonstrated that a specific capacitance (SC) of ca. 14.6 μF cm-2 was delivered by the S-CNTs with the specific surface area (SSA) of 207 m2 g-1, much larger than that of ca. 10.1 μF cm-2 for the L-CNTs with the SSA of 223 m2 g-1, the reason for which was that S-CNTs with two open ends, due to good ion penetrability, provided more entrances for electrolyte ions to access the inner surface easily through their shorter inner pathway so as to enhance their SSA utilization and geometric SC. The surface structure disruption of S-CNTs, owing to ultrasonication and oxidation during chopping process, deteriorated their electronic conductivity and resulted in an inferior power property in contrast to L-CNTs.

  15. Iridium-decorated multiwall carbon nanotubes and its catalytic activity with Shell 405 in hydrazine decomposition

    Iridium-functionalized multiwalled carbon nanotubes (Ir-MWNT) are the future catalyst support material for hydrazine fuel decomposition. The present work demonstrates decoration of iridium particle on iron-encapsulated multiwalled carbon nanotubes (MWNT) by wet impregnation method in the absence of any stabilizer. Electron microscopy studies reveal the coated iridium particle size in the range of 5–10 nm. Elemental analysis by energy dispersive X-ray diffraction confirms 21 wt% of Ir coated over MWNT. X-ray photoelectron spectroscopy (XPS) shows 4f5/2 and 4f7/2 lines of iridium and confirms the metallic nature. The catalytic activity of Ir-MWNT/Shell 405 combination is performed in 1 N hydrazine micro-thrusters. The thruster performance shows increase in chamber pressure and decrease in chamber temperature when compared to Shell 405 alone. This enhanced performance is due to high thermal conducting nature of MWNTs and the presence of Ir active sites over MWNTs

  16. Multiwalled carbon nanotube films as small-sized temperature sensors

    Di Bartolomeo, A.; Sarno, M.; Giubileo, F.; Altavilla, C.; Iemmo, L.; Piano, S.; Bobba, F.; Longobardi, M.; Scarfato, A.; Sannino, D.; Cucolo, A. M.; Ciambelli, P.

    2009-03-01

    We present the fabrication of thick and dense carbon nanotube networks in the form of freestanding films (CNTFs) and the study of their electric resistance as a function of the temperature, from 4 to 420 K. A nonmetallic behavior with a monotonic R(T ) and a temperature coefficient of resistance around -7×10-4 K-1 is generally observed. A behavioral accordance of the CNTF conductance with the temperature measured by a solid-state thermistor (ZnNO, Si, or Pt) is demonstrated, suggesting the possibility of using CNTFs as temperature small-sized (freely scalable) sensors, besides being confirmed by a wide range of sensitivity, fast response, and good stability and durability. Concerning electric behavior, we also underline that a transition from nonmetal to metal slightly below 273 K has been rarely observed. A model involving regions of highly anisotropic metallic conduction separated by tunneling barrier regions can explain the nonmetallic to metallic crossover based on the competing mechanisms of the metallic resistance rise and the barrier resistance lowering.

  17. Adsorption of Reactive Red M-2BE dye from water solutions by multi-walled carbon nanotubes and activated carbon

    Machado, Fernando M.; Bergmann, Carlos P. [Department of Material, Federal University of Rio Grande do Sul, Av. Osvaldo Aranha 99, Laboratory 705C, ZIP 90035-190, Porto Alegre, RS (Brazil); Fernandes, Thais H.M. [Institute of Chemistry, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, Postal Box 15003, ZIP 91501-970, Porto Alegre, RS (Brazil); Lima, Eder C., E-mail: profederlima@gmail.com [Institute of Chemistry, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, Postal Box 15003, ZIP 91501-970, Porto Alegre, RS (Brazil); Royer, Betina; Calvete, Tatiana [Institute of Chemistry, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, Postal Box 15003, ZIP 91501-970, Porto Alegre, RS (Brazil); Fagan, Solange B. [Department of Nanoscience, UNIFRA, R. dos Andradas 1614, ZIP 97010-032, Santa Maria, RS (Brazil)

    2011-09-15

    Highlights: {yields} Multi-wall carbon nanotube (MWCNT) and powdered activated carbon (PAC) adsorbents. {yields} Reactive Red M-2BE textile dye adsorbate. {yields} Kinetics was followed by Avrami fractional-order. {yields} The maximum adsorption capacities were 335.7 and 260.7 mg g{sup -1} for MWCNT and PAC. {yields} Synthetic effluents treatment. - Abstract: Multi-walled carbon nanotubes and powdered activated carbon were used as adsorbents for the successful removal of Reactive Red M-2BE textile dye from aqueous solutions. The adsorbents were characterised by infrared spectroscopy, N{sub 2} adsorption/desorption isotherms and scanning electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium at 298 K was fixed at 1 h for both adsorbents. The activation energy of the adsorption process was evaluated from 298 to 323 K for both adsorbents. The Avrami fractional-order kinetic model provided the best fit to the experimental data compared with pseudo-first-order or pseudo-second-order kinetic adsorption models. For Reactive Red M-2BE dye, the equilibrium data were best fitted to the Liu isotherm model. Simulated dyehouse effluents were used to check the applicability of the proposed adsorbents for effluent treatment.

  18. Chemical attachment of functionalized multiwalled carbon nanotubes on glassy carbon electrode for electrocatalytic application

    Highlights: • FMWCNTs were covalently attached on GC surface with the aid of alkyldiamine. • The attached FMWCNTs were stable for a wide potential window due to the robust C−N bond. • The composite electrode was prepared by electropolymerizing thiadiazole on FMWCNTs. • The detection limit of 0.27 μM (S/N = 3) of GMP was achieved using composite modified electrode. - Abstract: The covalent attachment of acid functionalized multiwalled carbon nanotubes (FMWCNTs) on glassy carbon (GC) electrode using 1,8-octanediamine (OD) as a linker via carbodiimide chemistry was described. The attachment of FMWCNTs on GC electrode were confirmed by attenuated total reflectance Fourier transform infra-red (ATR-FT-IR) spectroscopy, Raman, scanning electron microscopy (SEM) and electrochemical impedance studies. Raman spectrum of FMWCNTs modified surface shows the characteristic G and D bands at 1563 cm−1 and 1340 cm−1, respectively. This confirmed the successful attachment of FMWCNTs on the OD modified GC surface. Further, the attachment of FMWCNTs on OD modified surface via amide linkage was confirmed from the observed characteristic peak at 1681 cm−1 in the ATR-FT-IR spectrum. The SEM images showed that the covalently attached FMWCNTs retained their morphology similar to powder and the average diameter of them was found to be 58 nm. Unlike modification of FMWCNTs on gold substrates with the aid of conventional thiol linkers (Au−S bond), modification of them by the present method was stable for a wide positive potential window due to the robust C−N bond. To demonstrate the electrochemical stability of the MWCNTs modified electrode at more positive potential, guanosine 5′-monophosphate (GMP) was selected as a representative probe because its oxidation occurs at more than 1 V. It was found that the FMWCNTs modified electrode not only showed a stable signal for GMP but also enhanced its oxidation current when compared to bare GC electrode. Further, the present

  19. Voltammetric Determination of Ferulic Acid Using Polypyrrole-Multiwalled Carbon Nanotubes Modified Electrode with Sample Application

    Refat Abdel-Hamid

    2015-10-01

    Full Text Available A polypyrrole-multiwalled carbon nanotubes modified glassy carbon electrode-based sensor was devised for determination of ferulic acid (FA. The fabricated sensor was prepared electrochemically using cyclic voltammetry (CV and characterized using CV and scanning electron microscope (SEM. The electrode shows an excellent electrochemical catalytic activity towards FA oxidation. Under optimal conditions, the anodic peak current correlates linearly to the FA concentration throughout the range of 3.32 × 10−6 to 2.59 × 10−5 M with a detection limit of 1.17 × 10−6 M (S/N = 3. The prepared sensor is highly selective towards ferulic acid without the interference of ascorbic acid. The sensor applicability was tested for total content determination of FA in a commercial popcorn sample and showed a robust functionality.

  20. Unzipped Nanotube Sheet Films Converted from Spun Multi-Walled Carbon Nanotubes by O2 Plasma.

    Jangr, Hoon-Sik; Jeon, Sang Koo; Shim, Dae Seob; Lee, Nam Hee; Nahm, Seung Hoon

    2015-11-01

    Large-scale graphene or carbon nanotube (CNT) films are good candidates for transparent flexible electrodes, and the strong interest in graphene and CNT films has motivated the scalable production of a good-conductivity and an optically transmitting film. Unzipping techniques for converting CNTs to graphene are especially worthy of notice. Here, we performed nanotube unzipping of the spun multi-walled carbon nanotubes (MWCNTs) to produce networked graphene nanoribbon (GNR) sheet films using an 02 plasma etching method, after which we produced the spun MWCNT film by continually pulling MWCNTs down from the vertical well aligned MWCNTs on the substrate. The electrical resistance was slightly decreased and the optical transmittance was significantly increased when the spun MWCNT films were etched for 20 min by O2 plasma of 100 mA. Plasma etching for the optimized time, which does not change the thickness of the spun MWCNT films, improved the electrical resistance and the optical transmittance. PMID:26726645

  1. Surface modification of multi-wall carbon nanotube with ultraviolet-curable hyperbranched polymer

    Surface modification is a general and efficient approach to improve the compatibility of carbon nanotube (CNT) with various matrixes. Here we report the modification of multi-wall carbon nanotube (MWCNT) with hyperbranched polymer which contains UV reactive functional groups. The modification promotes the incorporation of CNT into UV-curable resin, and when cured under UV irradiation to form a homogeneous film, the CNT will be chemically bonded with the matrix by crosslinking photopolymerization. For the unique mechanical properties of CNT, the mechanical properties of the cured MWCNT/UV-curable resin film were greatly improved compared with pure resin film as indicated by the increasing of Young's modulus, tensile strength, and toughness

  2. On-chip purification via liquid immersion of arc-discharge synthesized multiwalled carbon nanotubes

    Hokkanen, Matti J.; Lautala, Saara; Shao, Dongkai; Turpeinen, Tuomas; Koivistoinen, Juha; Ahlskog, Markus

    2016-07-01

    Arc-discharge synthesized multiwalled carbon nanotubes (AD-MWNT) have been proven to be of high quality, but their use is very limited due to difficulties in obtaining them in a clean and undamaged form. Here, we present a simple method that purifies raw AD-MWNT material in laboratory scale without damage, and that in principle can be scaled up. The method consists of depositing raw AD-MWNT material on a flat substrate and immersing the substrate slowly in water, whereby the surface tension force of the liquid-substrate contact line selectively sweeps away the larger amorphous carbon debris and leaves relatively clean MWNTs on the substrate. We demonstrate the utility of the method by preparing clean individual MWNTs for measurement of their Raman spectra. The spectra exhibit the characteristics of high-quality tubes free from contaminants. We also show how one concomitantly with the purification process can obtain large numbers of clean suspended MWNTs.

  3. Third sound measurements of superfluid 4He films on multiwall carbon nanotubes below 1 K

    Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the 4th and 5th atomic layers. Sharp changes in the Q factor of the third sound are found at partial layer fillings. Temperature sweeps at a number of fill points show strong broadening effects on the Kosterlitz-Thouless (KT) transition, and rapidly increasing dissipation, in qualitative agreement with the predictions of Machta and Guyer. At the 4th layer completion there is a sudden reduction of the transition temperature TKT, and then a recovery back to linear variation with temperature, although the slope is considerably smaller than the KT prediction

  4. Preparation of 14C-Labeled Multi-walled Carbon Nano-tubes for Biodistribution Investigations

    A new method allowing the 14C-labeling of carboxylic acid functions of carbon nano-tubes is described. The key step of the labeling process is a de-carbonylation reaction that has been developed and optimized with the help of a screening method. The optimized process has been successfully applied to multi-walled carbon nano-tubes (MWNTs), and the corresponding 14C-labeled nano-tubes were used to investigate their in vivo behavior. Preliminary results obtained after i.v. contamination of rats revealed liver as the main target organ. Radiolabeling of NTs with a long-life radioactive nucleus like 14C, coupled to a highly sensitive autoradiographic method, that provides a unique detection threshold, will make it possible to determine for a long time period whether or not NTs remain in any organs after animal exposure. (authors)

  5. Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method

    Tsai, Wan-Lin; Wang, Kuang-Yu; Chang, Yao-Jen; Li, Yu-Ren; Yang, Po-Yu; Chen, Kuan-Neng; Cheng, Huang-Chung

    2014-08-01

    For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.

  6. Chemical splitting of multiwalled carbon nanotubes to enhance electrochemical capacitance for supercapacitors

    Li, Xinlu; Li, Tongtao; Zhang, Xinlin; Zhong, Qineng; Li, Hongyi; Huang, Jiamu

    2014-06-01

    Multiwalled carbon nanotubes (MWCNTs) were chemically split and self-assembled to a flexible porous paper made of graphene oxide nanoribbons (GONRs). The morphology and microstructure of the pristine MWCNTs and GONRs were analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. And the specific surface area and porosity structure were measured by N2 adsorption-desorption. The longitudinally split MWCNTs show an enhancement in specific capacitance from 21 F g-1 to 156 F g-1 compared with the pristine counterpart at 0.1 A g-1 in a 6 M KOH aqueous electrolytes. The electrochemical experiments prove that the chemical splitting of MWCNTs will make inner carbon layers opened and exposed to electrochemical double layers, which can effectively improve the electrochemical capacitance for supercapacitors.

  7. Ultra-high crystallinity millimeter long multiwall carbon nanotubes fabricated by mechanothermal method

    Manafi, S. A.; Rahimipour, M. R.; Soltanmoradi, A.

    2012-09-01

    In this work, multi-walled carbon nanotubes (MWCNTs) with ultra-high crystalline structure have been prepared by mechanothermal (MT) method. The novel super nanostructure is introduced for the first time as an extraordinary fullerene-carbon based material which, due to its special electronic and mechanical properties, can be used to construct unique building blocks for nanoengineering. Initially, high ultra-active graphite powder has been obtained by mechanical activation under Ar atmosphere. Finally, the mechanically activated product is heat-treated at 1350 °C for 3-4 h under an Ar gas flow. However, the crystallite size and crystallinity degree of the MWCNTs increased with the increase in annealing temperature.

  8. Oxygen Barrier of Multiwalled Carbon Nanotube/Polymethyl Methacrylate Nanocomposites Prepared by in situ Method

    Ajaya K. Pradhan; Sarat K. Swain

    2012-01-01

    Multiwalled carbon nanotubes (MWCNTs)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared by ultrasonic assisted emulsifier free emulsion polymerization technique with variable concentration of functionalized carbon nanotubes. MWCNTs were functionalized with H 2 SO 4 and HNO 3 with continuing sonication and polished by H 2 O 2 . The appearance of Fourier transform infrared absorption bands in the PMMA/MWCNT nanocomposites showed that the functionalized MWCNT interacted chemically with PMMA macromolecules. The surface morphology of functionalized MWCNT and PMMA/MWCNT nanocomposites were studied by scanning electron microscopy. The dispersion of MWCNT in PMMA matrix was evidenced by high resolution transmission electron microscopy. The oxygen permeability of PMMA/MWCNT nanocomposites gradually decreased with increasing MWCNT concentrations.

  9. Surface modification of multi-wall carbon nanotube with ultraviolet-curable hyperbranched polymer

    Zhou Wei; Xu Jianwen [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi Wenfang [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)], E-mail: wfshi@ustc.edu

    2008-04-30

    Surface modification is a general and efficient approach to improve the compatibility of carbon nanotube (CNT) with various matrixes. Here we report the modification of multi-wall carbon nanotube (MWCNT) with hyperbranched polymer which contains UV reactive functional groups. The modification promotes the incorporation of CNT into UV-curable resin, and when cured under UV irradiation to form a homogeneous film, the CNT will be chemically bonded with the matrix by crosslinking photopolymerization. For the unique mechanical properties of CNT, the mechanical properties of the cured MWCNT/UV-curable resin film were greatly improved compared with pure resin film as indicated by the increasing of Young's modulus, tensile strength, and toughness.

  10. Multi-Walled Carbon Nanotube Functionalization by Radical Addition Using Hydroxymethylene Groups.

    Rodríguez-Jiménez, Rubén; Alonso-Núñez, Gabriel; Paraguay-Delgado, Francisco; Espinoza-Gómez, Heriberto; Vélez-López, Ernesto; Rogel-Hernández, Eduardo

    2016-01-01

    Synthetic methodology and characterization of multi-walled carbon nanotubes (MWCNTs) function- alized with hydroxymethylene groups are reported. The MWCNTs were synthesized by the spray pyrolysis technique using toluene as carbon source and ferrocene as catalyst. Hydroxymethylation of MWCNTs was carried out by methanol using benzoyl peroxide (BPO) at different quantities (300 to 900 mg); the optimum BPO quantity was 300 mg. The resulting materials were characterized by FT-IR, Raman Spectroscopy, Thermal Gravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). The presence of the hydroxymethylene group on the MWCNTs surface was demonstrated by FT-IR, Raman Spectroscopy, TGA, EDS, TEM and Mass Spectrometry. The func- tionalized MWCNTs were not damaged by this methodology. PMID:27398563