High strength low density fiber

Abstract

A welded nanotube fiber and a method of forming such a fiber is disclosed. The method comprises applying a voltage or current signal to a nanotube bundle, either in an evacuated chamber or in a chamber in which additional process gasses are introduced. The fiber comprises a plurality of substantively parallel nanotubes, in which a plurality of the subtantially parallel nanotubes has been covalently bonded to other nanotubes in the fiber by welding.

1 . A welded nanotube fiber, comprising a plurality of substantively parallel nanotubes, in which a plurality of the substantially parallel nanotubes has been covalently bonded to other nanotubes in the fiber by welding. 
     
     
         2 . The fiber of  claim 1 , wherein the fiber has a strength-to-density ratio of greater than 10 GPa/(g/cm 3 ). 
     
     
         3 . The fiber of  claim 1 , in which the fibers are twisted. 
     
     
         4 . The fiber of  claim 1 , in which the fibers comprise a macroscopic carbon fiber bundle, wherein substantively all the nanotubes are in intimate contact with at least one other nanotube. 
     
     
         5 . The fiber of  claim 1 , in which the fiber is at least 5 μm in cross-section everywhere along it length. 
     
     
         6 . The fiber of  claim 1 , in which the nanotubes are harvested from at least one nanotube forest. 
     
     
         7 . A method of forming a welded nanotube fiber, comprising applying a voltage or current signal to a macroscopic nanotube bundle, the bundle comprising a plurality of nanotubes in substantively parallel alignment, wherein substantively all the nanotubes are in intimate contact with at least one other nanotube in the bundle.