Carbon Nanotubes (CNT's) are the ultimate material and the only material strong enough to build the space elevator. There are many pages on carbon nanotubes that discuss all aspects of them. Here we will just address how their characteristics affect the space elevator.
First some basics:
- CNT's are tubes of graphene sheets. Their strength comes from the fact that they have no raw edges where a tear might start.
- Dimensions: 1nm (single walled) to 25nm (multiwalled) diameter, lengths or 4 cm have been grown.
- Theoretical tensile strength: 300GPa (reference???)
- Extremely flexible (Baughman reference}
- Melting temperature in vacuum: 2000C (reference???)
- Elongation at break: 10% (reference???)
- Extremely resistant to chemicals
The primary issue has been to mass produce them with high quality and in a form that can be used to make high-strength materials.
Initial work with composites was promising but limits of the amount of CNT's that can be included in a matrix places a limit on the ultimate strength (Andrews, Kentucky).
More recent work at Cambridge and several other locations with gas phase production and direct spinning has progressed further and continues to move forward. Material now produced by these methods is stronger than any other material ever produced in macroscopic form.