Japanese researchers succeeded in making a high-density carbon nanotube (CNT) wire that has an electric conductivity of 2,800S/cm and does not contain any polymer.
The CNT wire was developed by Furukawa Electric Co Ltd and Japan's National Institute of Advanced Industrial Science and Technology (AIST). Currently, the electric conductivity of the wire is lower than those of common copper wires. But the researchers plan to continue the development in the aim of realizing a conductivity equivalent to them.
The CNT wire was made by (1) mixing a CNT-dispersed liquid with a congealed liquid (solvent), (2) discharging it from a nozzle and (3) solidifying it into fibers. This method is called "wet spinning."
In the past, CNT wires based on the wet spinning method used a solvent including a polymer, which is an insulator, and had an electric conductivity of about 100S/cm. The conductivity of 2,800S/cm is the world's highest for a CTN wire based on the wet spinning method, Furukawa said.
In the joint study with AIST, Furukawa researched on the production conditions of the CNT-dispersed liquid and the type of the solvent and found that a CNT wire can be spun by using an organic solvent containing no polymer under some conditions. This time, the company made a CNT wire that is about 80cm long by applying the conditions.
Furukawa aims to commercialize the wire as an electric wire for automotive wiring harness, whose weight is strongly required to be reduced, by making use of the high strength and light weight of the CNT wire. The company announced the latest results at 2012 MRS Fall Meeting & Exhibit, which took place from Nov 25 to 30, 2012, in Boston, the US.