How Does Carbon Fibre Get Its Strength?

Carbon fibre is made by heating a precursor polymer — usually polyacrylonitrile (PAN) — through several stages. First, the fibres are stabilised by heating to 200–300°C in air, which cross-links the polymer chains. Then carbonisation at 1,000–3,000°C in an inert atmosphere drives off non-carbon atoms, leaving chains of carbon atoms in a graphite-like crystal structure aligned along the fibre axis. Each filament is just 5–10 micrometres in diameter — thinner than a human hair — yet incredibly stiff and strong in tension. When embedded in an epoxy resin matrix, carbon fibre composites are five times stronger than steel per unit weight and twice as stiff, making them ideal for aerospace, motorsport, and high-performance sporting goods.