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Carbon nanotubes (CNTs) are a form of elemental carbon produced by one of a number of catalytic processes. They resemble graphite in that they consist of a network of carbon atoms arranged in six member rings. Their structure is similar to rolled sheets of graphite. Multi-walled carbon nanotubes (MWCNTs) are produced in quantities of tens to hundreds of tons per year by a number of manufacturers and are available at much lower cost than single walls. As their name implies, MWCNTs exhibit a tube within a tube within a tube structure.
In principle, both single and multi-walled CNTs can be used in plastic compounds to impart electrical conductivity or anti-static properties. Multi-walled tubes are used as a lower cost alternative to their single-walled counterparts, but because conduction occurs along only the outermost wall, substantially higher loadings (weight %) are required, as compared to single-walled tubes. This can have adverse effects on the properties of the base polymer.
To help bridge this gap, specialty multi-walled tubes (SMW-100) are available in research quantities through Aldrich Materials Science in collaboration with SouthWest Nanotechnologies. SMW-100 tubes have fewer walls (3 to 6) compared to conventional multi-walls (10 to 20+). Since conduction occurs on only the outermost wall, SMW-100 tubes have more conducting surfaces per unit weight than conventional multi-walled tubes, which have significantly more internal, non-conducting tubes.
SMW-100 CNTs are of high purity and exhibit fewer wall defects than conventional MWCNTs. They also have a higher and a more precisely controlled aspect ratio than conventional MWCNTs. These properties promote more consistent and reproducible electrical results in conductive composites.
The properties of CoMoCAT® Multi-Walled Carbon Nanotubes available from Aldrich Materials science are summarized in the Table 1.
Table 1. High Purity Multi-Walled Carbon Nanotubes Properties
|Aldrich Product Number
|SWeNT Prodcut Number
||CoMoCAT® Catalytic Chemical Vapor Deposition (CVD)|
|Number of Walls
|Dimensions (OD x L)
||6-9 nm x 5 ìm|
About Sigma Aldrich
Sigma-Aldrich® is a leading high-technology company. Through our Materials Chemistry Centers of Excellence in research and manufacturing we develop advanced, enabling materials for your micro/nanoelectronics, alternative energy, display/optoelectronics, nanotechnology and related materials science and engineering applications. Specialties include ALD precursors, ultra-high purity inorganic halides, fuel cell materials, electronic grade dyes, specialty monomers and cGMP grade polymers.
Source: Sigma-Aldrich and SouthWest Nanotechnologies
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