Dissolution Kinetics in Plasma-Enhanced Nitric Acid Solvolysis of CFRCs

The dissolution kinetics in conventional nitric acid and plasma-enhanced nitric acid solvolysis of composites were investigated. Unidirectional carbon fiber epoxy laminates originating from the scar of wind turbine blades were used for the study. The carbon fiber retrieval rate was experimentally determined as a function of dissolution time and composite mass. A kinetic model, which included disintegration of the polymer matrix and the mass transport of polymer fragments to the liquid phase, was implemented to investigate the main parameters that affect the dissolution rate. The plasma enhancement and the increase of the composite mass favor the carbon fiber retrieval rate, while process time slows down the matrix dissolution rate. The composite surface in contact with the liquid, solid-to-liquid volume ratio, solubility of the polymer matrix, and disintegration and mass transport rate coefficients have a significant effect on the dissolution rate, and the rate-limiting factors were revealed and analyzed.