HexTow™ fibers from Hexcel are produced in a continuous operation in which the polyacrylonitrile precursor undergoes a series of precisely controlled processes. Exposure to extremely high temperatures chemically changes the precursor, yielding high strength-to-weight and high stiffness-to-weight properties through oxidation, carbonization and graphitization. The successive surface treatment and sizing stages improve bonding and handleability. The resulting carbon fiber is stronger than steel, lighter than aluminum and as stiff as titanium. It can be supplied in two basic forms: Continuous Fiber and Chopped Fiber.