Oxidation kinetics of polyacrylonitrile-based carbon fibers in air and the effect on their tensile properties

Polyacrylonitrile-based carbon fibers are oxidized by air at temperatures from 400 to 700 °C. The mass loss, morphology, graphitic structure and residual properties are investigated. The activation energy is about 111 kJ/mol and is independent of carbonization temperature. With increasing oxidation temperature, the crystallite height decreases gradually, while the d002 spacing increases presumably due to combination of oxygen with carbon. The tensile strength decreases significantly, while the tensile modulus remains nearly unchanged. The increase in carbon fiber density after oxidation suggests that glass-like carbon in the fiber is easier to burn off than the more graphitic carbon.

► The oxidation activation energy of carbon fiber is about 111 kJ/mol.
► Groves along fiber axis remain even the mass loss due to oxidation was about 11%.
► Lc(0 0 2) decreases, d002 increases with increasing of oxidation temperature.
► Increasing of density after oxidation was observed.