Search Results

You are looking at 71 - 80 of 177 items for :

  • "carbon nanotubes" x
  • Refine by Access: All Content x
Clear All
Journal of Thermal Analysis and Calorimetry
Authors:
Sangram Samal
,
Elizabeth Fernandes
,
Federica Chiellini
, and
Emo Chiellini

Abstract  

In the present study polymeric membranes consisting of poly(vinyl alcohol) (PVA) and multi-walled carbon nanotubes (MWCNTs) were prepared by casting method and their morphological, thermal and de-swelling behaviour were characterized. The effect of MWCNTs in the hybrid membranes was more significant when its concentration was high. The thermo degradation (T d) and crystallization (T c) temperatures of PVA increased of 10 and 9 °C, respectively in presence of 50 × 10−2 w v−1% of MWCNTs (PVNT3). Besides, the amount of non-free water increases with increasing of MWCNTs probably due to a capillary effect.

Restricted access

Abstract  

Polyaniline/multi-walled carbon nanotube (PANI/MWNT) composites were prepared by in situ polymerization. Transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to characterize the PANI/MWNT composites. Thermal stability and glass transition temperature (T g) were measured by thermogravimetry (TG) and temperature modulated differential scanning calorimetry (TMDSC), respectively. The TG and derivative thermogravimetry (DTG) curves indicated that with augment of MWNTs content, the thermal stability of PANI/MWNT composites increased continuously. While, T g increased and then decreased with the MWNTs content increasing from 0 to 20 mass%.

Restricted access

Summary In this work the kinetics of the high-temperature oxidation of the powder amorphous carbon and bulk single-wall carbon nanotubes is studied. The thermal degradation of the sample is measured by differential scanning calorimetry using the continuous heating regime up to 1273 K. Also, the oxidation resistance of the samples is evaluated by the mass loss in a thermogravimetric analyzer. Both flowing and static oxygen and dry-air atmospheres are used. The specific role of the external diffusivity of the reagent gas is analyzed. The kinetics of the chemical reaction is specified using the Kissinger, Coats and Redfern methods.

Restricted access

] Karlsson H. L. , Cronholm P. , Gustafsson J. , Moller L. ( 2008 ) Copper oxide nanoparticles are highly toxic: a comparison between metal oxide nanoparticles and carbon nanotubes . Chemical research in toxicology 21 ( 9

Open access

Abstract  

The study was undertaken to evaluate the feasibility of oxidized multiwalled carbon nanotube (oxidized MWCNT) for the removal of radiocobalt (60Co) from aqueous solutions. The oxygen functional groups of oxidized MWCNT were characterized by FT-IR and XPS. Batch experiments were performed to study the sorption of cobalt as a function of contact time, solid contents, pH, ionic strength, foreign ions, and temperature. Two kinetic models viz. pseudo-first-order and pseudo-second-order were used to determine kinetic sorption parameters, and the kinetic sorption could be described more favorably by the pseudo-second-order model. The thermodynamic parameters (∆G°, ∆S°, ∆H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on oxidized MWCNT was an endothermic and spontaneous processes. The results suggest that oxidized MWCNT can be used efficiently in the treatment of industrial effluents containing radioactive and heavy metal ions.

Restricted access

Abstract  

Multi-walled carbon nanotubes (MWCNTs) have remarkable properties. However, their thermal stability characteristics, which may represent potential hazards during the production or utilization stage, concern unsafe or unknown properties researches. Our aim was to analyze the thermokinetic parameters of different heating rates by differential scanning calorimetry (DSC) and thermogravimetric analyzer (TG), and then to compare thermal decomposition energy parameters under various conditions by well-known kinetic equations. MWCNTs were acidified via nitric acid (HNO3) in various concentrations from 3 to 15 N and were characterized by means of Fourier transform infrared (FTIR) spectrometry. For original and modified MWCNTs, we further identified the thermal degradation characteristics of the functional group by TG-FTIR. Finally, we established an effective and prompt procedure for receiving information on thermal decomposition characteristics and reaction hazard of MWCNTs that could be applied as an inherently safer design during normal or upset operation.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors:
Aleksandr Novikov
,
Dmitry Malikov
,
Sergey Vinokurov
,
Irina Kazinskaya
,
Tatyana Goryachenkova
, and
Boris Myasoedov

Abstract  

Neptunium(V) sorption from simulated and natural ground waters, containing ammonium carbonates, acetates, oxalates and citrates, on multi-walled carbon nanotubes (MWCNT) «Taunit»® was studied. It has been discovered that ammonium acetate and carbonate are not adsorbed on MWCNT «Taunit», but humic acid, oxalates and citrates are adsorbed quite efficiently. Neptunium is extracted from the ammonium carbonate solution by MWCNT «Taunit» with low sorption degrees. While conducting the sorption process from the ammonium carbonate solution with addition of organic substances, it has been revealed that the neptunium extraction degree is not dependent on addition of humic acid and acetate. At the same time, the extraction degree is substantially increased at addition of ammonium oxalate and citrate. It enables modifying MWCNT «Taunit» by means of related organic ligands and using them for the purpose of extraction and concentration of neptunium from contaminated natural waters.

Restricted access

Abstract  

Nanotechnology has been intensively investigated by bibliometric methods due to its technological importance and expected impacts on economic activity. However, there is less focus on nanobiotechnology, which is an emerging research domain in nanotechnology. In this paper, we study the current status of the former, with our primary focus being to reveal the structure and research domains in nanobiotechnology. We also examine country and institutional performance in nanobiotechnology. It emerged that nanostructures, drug delivery and biomedical applications, bio-imaging, and carbon nanotubes and biosensors are the major research domains, while the USA is the leading country, and China has also made substantial contribution. Most institutions having a major impact in the area of nanobiotechnology are located in the USA.

Restricted access

://www.nanopharma.cz/en/products-and-technology/technology [2] Kučerová L. ( 2017 ), Detection of Deformation and Voltage by Polymer Nanocomposite with Integrated Carbon Nanotube Layer . Bachelor Thesis , Tomas

Open access

Abstract  

The effects of multi-walled carbon nanotubes (MWNTs) on the phase change enthalpy (ΔH) and the thermal conductivity (κ) of a solid-liquid phase change materials (PCM), palmitic acid (PA), have been investigated. The results showed that both the ΔH and the κ of the composite were lower than that of PA when the loading of MWNTs was small. As the concentration of MWNTs in the composites increased, the ΔH of the composites was slightly improved and then decreased linearly. However, the κ of the composites was monotonously increased from the minimum value. When the loading of MWNTs increased to 5% and no surfactant was added, the κ of the composite was enhanced to be 26% higher than that of PA. The κ of the composite could be enhanced by CTAB instead of SDBS when the loading of MWNTs was small, as SDBS showed no obvious effect on the κ of the composites. Furthermore, the effects of surface modification of MWNTs on the ΔH and the κ of the composites have also been investigated.

Restricted access