Enhanced and Eco-Friendly Recycling of Carbon-Fiber-Reinforced Plastics Using Water at Ambient Pressure

Abstract

In general, the cross-linked epoxy resin is a thermosetting resin, which cannot be dissolved in an organic solvent. Therefore, materials containing epoxy resins, especially carbon-fiber-reinforced plastics (CFRPs), are difficult to recycle. In our study, we succeeded in dissolving the epoxy resin within 2 h at atmospheric pressure and a reaction temperature of 100 degrees C, which are optimal conditions for the depolymerization; this was achieved by using an aqueous NaOCl solution, which made it possible to recycle these CFRPs. Further, the depolymerization mechanism was determined, which involved the hydroxyl radicals generated from the aqueous NaOCl solution. We identified that an initial pH of 12.05 and a reaction temperature of 100 degrees C are optimal conditions for the depolymerization of CFRP. Moreover, the reclaimed carbon fibers (CFs) showed physical properties almost similar to those of virgin CFs. In addition, high value-added products were fabricated by using the CFs and resin decomposition products recovered after the decomposition of CFRPs. Thus, the recyclability of CFRPs was maximized to realize minimizing the generation of waste.