Chemical Modification of Polymer Structure

The carbonization step is carried out in an inert atmosphere (high-purity N2) above 1000°C to yield carbon fibers containing 93-95% carbon [Eq. (61)] and a tensile modulus ( ) of 140-200 GPa. This grade is mostly used in sporting goods and in composites. 

To achieve fibers in which the carbon crystals are further stretched and aligned, graphitization takes place around 2000-3000°C. These graphite fibers have a carbon content greater than 99% and a tensile modulus of 400-1000 GPa. For comparison, the tensile modulus of carbon nanotubes is 1000 GPa, and of diamond 1200 GPa. 

---