A research team from Tsinghua University in Beijing has developed a fibre they say is so strong it could even be used to build an elevator to space.
They say just 1 cubic centimetre of the fibre – made from carbon nanotube – would not break under the weight of 160 elephants, or more than 800 tonnes. And that tiny piece of cable would weigh just 1.6 grams.
“This is a breakthrough,” said Wang Changqing, a scientist at a key space elevator research centre at Northwestern Polytechnical University in Xian who was not involved in the Tsinghua study.
The Chinese team has developed a new “ultralong” fibre from carbon nanotube that they say is stronger than anything seen before, patenting the technology and publishing part of their research in the journal Nature Nanotechnology earlier this year.
“It is evident that the tensile strength of carbon nanotube bundles is at least 9 to 45 times that of other materials,” the team said in the paper.
They said the material would be “in great demand in many high-end fields such as sports equipment, ballistic armour, aeronautics, astronautics and even space elevators”.
Those cables would need to have tensile strength – to withstand stretching – of no less than 7 gigapascals, according to Nasa. In fact, the US space agency launched a global competition in 2005 to develop such a material, with a US$2 million prize attached. No one claimed the prize.
Now, the Tsinghua team, led by Wei Fei, a professor with the Department of Chemical Engineering, says their latest carbon nanotube fibre has tensile strength of 80 gigapascals.
Carbon nanotubes are cylindrical molecules made up of carbon atoms that are linked in hexagonal shapes with diameters as small as 1 nanometre. They have the highest known tensile strength of any material – theoretically up to 300 gigapascals.
But for practical purposes, these carbon nanotubes must be bonded together in cable form, a process which is difficult and can affect the overall strength of the final product.
According to Wang, the space lift researcher, the transport system would need more than 30,000km of cable, and it would also need other structures such as a rail and a shield to protect against space debris and other environmental hazards.
Japan launched two satellites last month in an experiment to study elevator movement in space – the first time this has been done – involving a mini-lift travelling along a cable from one satellite to another. It has yet to report the results of the experiment. China has also conducted space tethering tests but the details were classified.
Song Liwei, who studies mechanical batteries at the Harbin Institute of Technology in Heilongjiang, said if the carbon nanotube fibre could be mass-produced and if it significantly increased the energy density of mechanical batteries, it “would kill fossil fuel engines”.