Multiwalled carbon nanotubes properties

Another interesting type of novel carbons applicable for supercapacitors, consists of a carbon/carbon composite using nanotubes as a perfect backbone for carbonized polyacrylonitrile. Multiwalled carbon nanotubes (MWNTs), due to their entanglement form an interconnected network of open mesopores, which makes them optimal for assuring good mechanical properties of the electrodes while allowing an easy diffusion of ions. 

Goh HW, Goh SH, Xu GQ, Lee KY, Yang GY, Lee YW, Zhang WD (2003). Optical limiting properties of double-C60-end-capped poly(ethylene oxide), double-C -end-capped polyethylene oxide)/poly(ethylene oxide) blend, and double-C -end-capped poly(ethylene oxide)/multiwalled carbon nanotube composite. J. Phys. Chem. B 107 6056-6062. 

Z. Wu, W. Feng, Y. Feng, Q. Liu, X. Xu, T. Senkino, A. Fuji, M. Ozaki, Preparation and characterization of chitosan-grafted multiwalled carbon nanotubes and their electrochemical properties, Carbon, vol. 45, pp. 1212-1218, 2007. 

J.Y. Kwon, H.D. Kim, Preparation and properties of acid-treated multiwalled carbon nanotubes/waterborne polyurethane nanocomposites, Journal of Applied Polymer Science, vol. 96, pp. 595-604, 2005. 

George and Bhowmick [147] have also studied the influence of the polarity of EVA (40, 50, 60, and 70% vinyl acetate content) and the nature of the nanofiller [expanded graphite (EG), multiwall carbon nanotubes (MWCNTs), and CNFs] on the mechanical properties of EVA/carbon nanofiller nanocomposites. They pointed out that the enhancement in mechanical properties with the addition of various... 

Some potentially relevant work concerns the attachment of magnesium hydroxide nanoparticles onto multiwall carbon nanotubes (MWCNTs).92 These were prepared from water-in-oil emulsions specifically for conversion into MgO to functionalize and preserve the mechanical and the electrical properties of the CNTs, although not for fire-retardant purposes. However, although more speculative, this work may be of interest as it has been reported that combinations of M WCNT and micron-sized particles of ATH in EVA function as very efficient fire retardants through enhanced char formation and coherency.93... 

Double-walled carbon nanotubes (DWNTs), first observed in 1996, constitute a unique family of carbon nanotubes (CNTs). -2 DWNTs occupy a position between the single-walled carbon nanotubes (SWNTs) and the multiwalled carbon nanotubes (MWNTs), as they consist of two concentric cylinders of rolled graphene. DWNTs possess useful electrical and mechanical properties with potential applications. Thus, DWNTs and SWNTs have similar threshold voltages in field electron emission, but the DWNTs exhibit longer lifetimes.3 Unlike SWNTs, which get modified structurally and electronically upon functionalization, chemical functionalization of DWNTs surfaces would lead to novel carbon nanotube materials where the inner tubes are intact. The stability of DWNTs is controlled by the spacing of the inner and outer layers but not by the chirality of the tubes 4 therefore, one obtains a mixture of DWNTs with varying diameters and chirality indices of the inner and outer tubes. DWNTs have been prepared by several techniques, such as arc discharge5 and chemical vapor depo-... 

Kwon et al. compared WPU/MWNT with WPU/nitric acid treated multiwalled carbon nanotube (A-CNT) composites (20). The tensile strength and modulus of the WPU/A-CNT composites were higher than those of the WPU/MWNT composites with the same CNT content. The better mechanical properties of WPU / A-CNT composites can perhaps be attributed to higher content of polar groups of A-CNTs thus inducing higher interfacial interactions between A-CNTs and WPU chains. 

This chapter is an overview of the synthesis and properties of PVA/ nanotube composites. Various films and fibers have been processed from carbon nanotube and PVA dispersions. Compared to other polymers, PVA exhibit particularly strong interaction with single-walled as well as multiwalled carbon nanotubes. This leads to unique properties which are not observed in other nanotube polymer nanocomposites. In particular, this literature review confirms... 

The last few years have seen the extensive use of nanoparticles because of the small size of the filler and the corresponding increase in the surface area, allowing to achieve the required mechanical properties at low filler loadings. Nanometer-scale particles including spherical particles such as silica or titanium dioxide generated in-situ by the sol-gel process (4-8), layered silicates (9-12), carbon (13) or clay fibers(14,15), single-wall or multiwall carbon nanotubes (16,17) have been shown to significantly enhance the physical and mechanical properties of rubber matrices. 

Toupin M., Brousse T., Belanger D. Influence of microtexture on the charge storage properties of chemically synthesized manganese dioxide, Chem Mater 2002 14 3946-52. Wu N.L. Nanocrystalline oxide supercapacitors. Mater Chem Phys 2002 75 6-11. Frackowiak E., Metenier K., Bertagna V., Beguin F. Supercapacitor electrodes from multiwalled carbon nanotubes. Appl Phys Lett 2000 77 2421-3. 

Chan KHK et al (2010) Morphologies and electrical properties of electrospun poly (R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate/multiwalled carbon nanotubes fibers. J Appl Polym Sci 116(2) 1030-1035... 

Zhang H, Wang ZG, Zhang ZN et al (2007) Regenerated-ceUulose/multiwalled-carbon-nanotube composite fibers with enhanced mechanical properties prepared with the ionic liquid l-allyl-3-methylimidazolium chloride. Adv Mater 19 698-704... 

After having made the acquaintance of fuUerenes and of single- and multiwalled carbon nanotubes, the question arises on the existence of multiwalled fullerenes. Such carbon cages concentrically arranged one inside another are also called carbon onions. In comparison to other new carbon materials, they have by far been studied less. Chiefly this is because only small amounts of those are available. Still they represent an interesting structural variant of carbon. This chapter deals with their structure, different methods of preparation, and first results regarding their properties. 

Little is known so far about the chemical properties, yet first results suggest a reactivity similar to that of multiwalled carbon nanotubes. Furthermore, a transformation of nano-onions into other forms of carbon can be achieved by heating (equihbration as faceted nanoparticles) or electron bombardment. In large carbon onions, a formation of small diamond clusters due to internal self-compression has been observed. These grow up to be nanoscale diamond particles under complete consumption of the onion structure. 

Carbon nanotubes, generally in the form of multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs), may exhibit specific adsorption and electronic properties in comparison with activated carbon, due primarily to their peculiar morphology, the role of defects, the probability of opening or closing of the tubes, and so on [5], which are believed to induce cooperative or synergetic interactions between metal or metal oxide... 

Gupta, S. and J. Farmer, Multiwalled carbon nanotubes and dispersed nanodiamond novel hybrids Microscopic structure evolution, physical properties, and radiation resilience. J. Appl. Phys. 2011,109(1), 014314-014314-15. 

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