Carbon Nanotubes
Carbon nanomaterials, such as carbon nanotubes, nanofibres and graphene, are becoming increasingly important in many applications due to their fascinating properties. Carbon nanotubes can behave like metals or semiconductors, can conduct electricity better than copper, can transmit heat better than diamond, and rank among the strongest materials known.
- Diameter: SWCNT, 0.6-1.8 nm; MWCNT and CNF, 5-100 nm.
- Electrical: Metalic/semiconducting.
- Density: 1.33-1.40 g/cm3 (Al: 2.7 g/cm3).
- Tensile Strength: 45GPa (High strength steel alloys:~2GPa).
- Current Carrying Capacity: 109 A/cm2 (copper: 106 A/cm2).
- Heat Transmission: 6000W/mK (Diamond: 3320 W/mK).
- Required field for field emission: 1-3V/mm (Mo tips: 20-100 V/mm).
(Source: P.G. Collins and P. Avouris, Scientific American, Dec 2000, 38-45)
Due to the high aspect ratio, the quasi-one-dimensional structure, and the graphite-like arrangement of the carbon atoms in the shells, nanotubes exhibit a very broad range of unique chemical, mechanical and electronic properties. The properties of nanotubes can change depending on their different structures and quality. Large increases in strength, toughness, and superior electrical and thermal properties, are potential benefits of using nanotubes as the filler material in polymer-based composites when compared with traditional carbon, glass or metal fibres.
The remarkable electrical and mechanical properties of carbon nanotubes make them excellent candidates for a range of electrical, mechanical and electro-mechanical applications. Carbon fibres have already been used to strengthen a wide range of materials, and the special properties of carbon nanotubes mean that they could be the ultimate-strength fibre. Since they are composed entirely of carbon, nanotubes also have a low specific weight.
