Multi-walled carbon nano-tube

Carbon nanotubes (CNTs) are seamless cylindrical graphitic nanofibers made of sp carbon atoms. A carbon nanotube may consist of a single graphitic sheet [single-walled carbon nanotubes (SWCNTs) [8] as shown in Figure 14.2(c)] or multiple concentric graphitic sheets [multi walled carbon nano tubes (MWCNTs)... 

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Figure 14.2 Some representative sp carbon materials (a) graphite (b) Ceo (c) single-walled carbon nano tubes (d) multi walled carbon nanotube (e) carbon nanofibers grown by plasma-enhanced chemical vapor deposition.

Carbon nano tubes were first discovered by Iijima in 1991 during the course of their work on fullerenes. Nanotubes belong to a promising group of nanomaterials. Although other nano tubes based on boron nitride and molybdenum have also been reported, currently CNTs are by far the most important group, and may be characterized in two classes single-walled (SW) CNTs and multi-walled (MW) CNTs. 

Stress strain curves for silica nano fibre, CNF and systems formulated with more refined single and multi walled nano tubes are shown in Figure 12. The further simplification of the stress strain response over the PDMS formulated with fumed silica is apparent. There is no Mullins effect, in any of the tubular carbon modified systems, they all have a non complex modulas and a highly linear stress strain response. 

Carbon nanotubes can be imagined as a sheet of graphite that has been rolled into a tube. The properties of nanotubes depend on atomic arrangement, the diameter and length of the tubes, and the morphology, or nano structure. Nanotubes exist as either single-walled (SWCNT) or multi-walled (MWCNT) structures. The MWCNTs are composed of concentric SWCNTs [202]. 

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