Recycling of Carbon Fiber Reinforced Polymers in a Subcritical Acetic Acid Solution

A novel single-stage solvolysis process is demonstrated for recycling carbon fibers from an epoxy-based composite material using 50 wt% acetic acid solution under subcritical conditions. The process yields 100% recovery efficiency for fibers in less than 30 min at 300 °C. Qualitative SEM / EDS analysis of the fibers reveals that the recovered fibers are entirely free of resin, while the carbon fiber surfaces were not damaged. SEM images and gravimetric measurements of the composites treated at lower temperatures and short residence times show an initial increase in mass of the CFRP samples, suggesting a two-step process, consisting of initial composite swelling due to uptake of solvent, followed by depolymerization and chemical decomposition of the polymer. FTIR and GC-MS analyses confirm resin decomposition and production of aromatic and aliphatic compounds, which could potentially be recovered for re-use.