Versus the nanotube’s neatly organized, tightly bonded configuration, carbon fiber is what quantum chemists call turbo­stratic, meaning flat layers, each one a single carbon atom thick, stacked somewhat haphazardly on top of one another. The carbon nanotube’s superior atomic-bonded crystal structure is what makes it the strongest, stiffest material known to man and nearly 20 times stronger per pound than carbon fiber. Carbon Fiber: In comparison to a nanotube, carbon fiber’s turbostratic structure is messier and weaker.