Liudmyla Karachevtseva; Mykola Kartel; Wang Bo; Yurii Sementsov; Viacheslav Trachevskyi; Oleg Lytvynenko; Volodymyr Onyshchenko
Abstract
Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. The possibilities to enhance the properties of nanostructured surfaces were demonstrated on “polymer-multiwall carbon nanotube” composites. Influence of sp < sup > 3 hybridization ...
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Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. The possibilities to enhance the properties of nanostructured surfaces were demonstrated on “polymer-multiwall carbon nanotube” composites. Influence of sp < sup > 3 hybridization bonds on polymer crystallization and strengthening was investigated in composite films of polyethyleneimine, polypropylene and polyamide with multiwall carbon nanotubes. It was established that the effective way to enhance the strength properties of “polymer-multiwall carbon nanotube” composites is the composite crystallization and sp < sup > 3 C-C tetrahedrons organization between nanotubes supported by resonance γω(C?)? and γω(CH2) vibrations in the intrinsic electric field 6×10 3 V/cm between nanotube and polymer matrix. Tensile strength for polyamide-6 composites at 0.25% CNT increases 1.7 times and tensile deformation – 2.3 times.
Liudmyla A. Karachevtseva; Mykola T. Kartel; Oleg O. Lytvynenko; Volodymyr F. Onyshchenko; Kostyantyn A. Parshyn; Olena J. Stronska
Abstract
We synthesized light-emitting coatings of CdS nanocrystals in polyethyleneimine and polyethyleneimine with multiwall carbon nanotubes on macroporous silicon. The photoluminescence of CdS nanocrystals in polyethyleneimine on oxidized macroporous Si is more intense in comparison with substrates c-Si, macroporous ...
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We synthesized light-emitting coatings of CdS nanocrystals in polyethyleneimine and polyethyleneimine with multiwall carbon nanotubes on macroporous silicon. The photoluminescence of CdS nanocrystals in polyethyleneimine on oxidized macroporous Si is more intense in comparison with substrates c-Si, macroporous Si, and macroporous Si with a microporous layer, and is maximal for structures with maximal intensity of the local electric field at the Si-SiO2 interface. This indicates a significant decrease of non-radiative recombination in the CdS-polyethyleneimine layer due to electron flow from the silicon matrix to the nanocrystal layer. The photoluminescence of polyethyleneimine with carbon multiwall nanotubes on macroporous Si with a microporous layer is about six times more intense in comparison with substrates c-Si, macroporous Si and oxidized macroporous Si. This indicates a non-radiative proton recombination decrease due to hydrogen atoms on the boundary between Si matrix with microporous layer and “polymer-nanoparticles” coating.
B. V. Mohan Kumar; R. Thomas; A. Mathew; G. Mohan Rao; D. Mangalaraj; N. Ponpandian; C. Viswanathan
Abstract
Multiwall carbon nanotubes (MWCNT) are synthesised by cost effective method of pyrolysing xylene (as hydrocarbon, precursor) in the presence of ferrocene (as catalyst) at 750 o C. The so obtained MWCNTs has a length ranging from 90 µm to 300 µm and diameter ranging from 20 nm to 200 nm depending ...
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Multiwall carbon nanotubes (MWCNT) are synthesised by cost effective method of pyrolysing xylene (as hydrocarbon, precursor) in the presence of ferrocene (as catalyst) at 750 o C. The so obtained MWCNTs has a length ranging from 90 µm to 300 µm and diameter ranging from 20 nm to 200 nm depending on the amount of ferrocene added to the xylene for the synthesis. The diameter of the MWCNT’s increased with the increase in ferrocene content in the precursor solution. Bigger agglomerates of iron particle lead to the growth of larger diameter MWCNTs. These MWCNTs with higher concentration of iron nanoparticles in it are useful for catalytic applications. X-ray diffraction (XRD) of the as-synthesised MWCNTs showed a graphitic-like peak (002). Field emission scanning electron microscope (FESEM) is utilized for its morphological analysis, Raman analysis showed the presence of D band (about 1350 cm -1 ) and G band (about 1580 cm -1 ) indicating high crystalline graphitic layers. Fourier transform infrared (FTIR) studies in the transmission mode were carried out in the range 400 - 4000 cm -1 (peaks at 1386, 1639, 2363, 3434, 3747 cm -1 etc.) for bond stretching analysis. All the characterization processes were carried out before and after purification process. The MWCNT’s diameter and their distribution are studied with the help of ImageJ software using the FESEM micrographs.
H. Kathyayini;N. Nagaraju
Abstract
Al(OH)3 from different sources has been used as supports for a mixture of Fe/Co salts and employed in the synthesis of Multiwall Carbon nanotubes by Catalytic Chemical Vapour Deposition method. These supported-catalysts have been characterized by Scanning Electron Microscopy, Powdered X-ray diffraction, ...
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Al(OH)3 from different sources has been used as supports for a mixture of Fe/Co salts and employed in the synthesis of Multiwall Carbon nanotubes by Catalytic Chemical Vapour Deposition method. These supported-catalysts have been characterized by Scanning Electron Microscopy, Powdered X-ray diffraction, and Thermo gravimetric studies. Surface area was determined by N2 adsorption technique. Carbon nanotubes synthesis reactions have been conducted at 700 o C using acetylene as the hydrocarbon source in N2 atmosphere. The quality and quantity of Multiwall carbon nanotubes depend not only on the carbon source, the textural & structural properties of the support and also their interactions with the active components available on the surface.
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