Schematic structures of various fibers.With decreasing disorder and defect density, the fiber strengthincreases (left to right). (Left) Typical commodity textile fiber contains amorphous and crystalline regions aswell as voids and foreign particles; tensile strength, ~0.5 GPa. (Middle) High-performance polymer fiberscontain chain ends, entanglements, voids, and defects; tensile strength, ~5 GPa. The structure of currentlyproduced carbon nanotube fibers resembles this structure. In addition, carbon nanotube fibers often containforeign particles in the form of catalysts. (Right) On the basis of predicted strain to failure, ideal car-bon nanotube fibers without defects or entanglements will have a specific tensile strength of 70 N/tex; for asingle-wall carbon nanotube fiber a diameter of 2 nm, this would translate to a tensile strength of 70 GPa.