A carbon nanotube is a tube-shaped material, made of carbon, having a diameter measuring on the nanometer scale.

A nanometer is one-billionth of a meter, or about 10,000 times smaller than a human hair. CNT are unique because the bonding between the atoms is very strong and the tubes can have extreme aspect ratios.

A carbon nanotube can be as thin as a few nanometers yet can be as long as hundreds of microns. To put this into perspective, if your hair had the same aspect ratio, a single strand would be over 40 meters long.

Some of the properties of CNTs are as follows –

a. CNTs have High Electrical Conductivity

b. CNTs have Very High Tensile Strength

c. CNTs are Highly Flexible- can be bent considerably without damage

d. CNTs are Very Elastic ~18% elongation to failure

e. CNTs have High Thermal Conductivity

f. CNTs have a Low Thermal Expansion Coefficient

g. CNTs are Good Electron Field Emitters

There are many different types of carbon nanotubes, but they are normally categorized as either single-walled (SWNT) or multi-walled nanotubes (MWNT).

A single-walled carbon nanotube is just like a regular straw. It has only one layer, or wall.

Multi-walled carbon nanotubes are a collection of nested tubes of continuously increasing diameters.

They can range from one outer and one inner tube (a double-walled nanotube) to as many as 100 tubes (walls) or more.