Carbon Nanotubes

19 February 2007

Since the carbon nanotubes nearly fifteen years ago, two types of nanotubes has been discovered and are being used for various applications. The two types of carbon nanotubes known as single wall carbon nanotube (SWNT) and multiple wall carbon nanotube (MWNT) not only has been discovered but they have been successfully prepared and used in commercial applications. These carbon nanotubes are similar to cylinders, however a single wall carbon nanotube has only one cylinder while a multi wall tube has many rested cylinders.

Most single wall nanotubes (SWNT) have a diameter of approximately 1 nm and it is very expensive to produce. The single wall nanotube will play an important role in future carbon nanotechnology. The structure of single wall nanotube can be conceptualized by wrapping a single layer of graphene to form a cylinder. The advantages of single wall nanotubes over multi wall nanotubes are that these nanotubes display excellent electrical properties and therefore are ideal for many electronics applications. In multi wall nanotubes (MWNT), multiple layers of graphite are rolled to form a tube and the advantages of MWNT are improves chemical resistance.

Some of the important properties of carbon nanotubes include excellent tensile strength and excellent elastic modulus. Due to a unique electronic structure of single atomic graphite layer, the electrical current density in metallic nanotubes may have several hundred times greater than the metals such as copper or silver. The main uses of these single wall or multiple wall carbon nanotubes will be in various nanotechnology engineering in the days ahead. These nanotubes are already being used in composite fibers, steel and various other electrical and electronic applications.

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