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Carbon Fiber 101 - How Is It Made?

A common method of making carbon filaments is the oxidation and thermal pyrolysis of polyacrylonitrile (PAN), a polymer based on acrylonitrile used in the creation of synthetic materials. Like all polymers, polyacrylonitrile molecules are long chains, which are aligned in the process of drawing continuous filaments. When heated in the correct conditions, the non-carbon constituents evaporate away, the chains bond side-to-side (ladder polymers) and form narrow graphene sheets which eventually merge to form a single, jelly roll-shaped or round filament. The result is usually 93–95% carbon. Lower-quality Fiber can be manufactured using pitch or rayon as the precursor instead of PAN.



The carbon fiber can become further enhanced by heat treatment processes. Carbon heated in the range of 1500-2000 °C (carbonization) exhibits the highest tensile strength (820,000 psi or 5,650 MPa or 5,650 N/mm²), while carbon Fiber heated from 2500 to 3000 °C (graphitizing) exhibits a higher modulus of elasticity (77,000,000 psi or 531 GPa or 531 kN/mm²).