Recycling of carbon fiber reinforced plastic containing amine-cured epoxy resin using supercritical and subcritical fluids

Chemical recycling of carbon fiber reinforced plastic (CFRP) containing an amine-cured epoxy as the matrix resin was investigated with a process using supercritical alcohols or ketones as solvents. Amine-cured epoxy resin was decomposed by a supercritical solvent (methanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, acetone, or methyl ethyl ketone) at 320 °C in the reaction time range 6–120 min. The decomposition rate depended on the solvent, and super- and subcritical acetone were ultimately selected as optimal for rapidly degrading the matrix resin. The decomposition rate of the epoxy resin using supercritical acetone was expressed by a surface reaction and shrinking core model. The recovered carbon fibers from the CFRP retained the shape of the plain fabric sheets and their tensile strength reduction was negligible.