Chemical recycling of carbon fibre reinforced composites in nearcritical and supercritical water

The potential for recycling of carbon fibre reinforced epoxy composites in water at supercritical or nearcritical conditions was studied. Experiments were devised in order to identify the significant process parameters that affect fibre reinforced composite recovery potential including temperature, time, oxidant and catalyst concentration. Experiments were performed in a batch-type reactor (10 mL) without stirring, with temperatures ranging from 523 to 673 K, pressures from 4.0 to 27.0 MPa and reaction times from 1 to 30 min. The efficiency of resin removal reached ca. 79.3 wt.% under supercritical water conditions with further improvement through the use of potassium hydroxide as alkali catalyst (up to 95.3 wt.%). The tensile strength of the reclaimed fibres was between 90% and 98% than that of the virgin fibres. A second-order kinetic equation was implemented to model the reactive extraction process.