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 °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 °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.

Liquefaction of Lignin Using Chemical Decomposition and Its Application to Polyurethane Foam

“…The mold was placed in an oven for 1 h at 80 °C. 14 This preparation process for synthesizing PUFs is shown in Scheme S1 .…”

“…The reaction mixture was then poured into a 50 × 50 × 20 mm 3 mold lined with aluminum foil and the lid of the mold was quickly closed. The mold was placed in an oven for 1 h at 80 °C . This preparation process for synthesizing PUFs is shown in Scheme S1.…”

“…The mold was placed in an oven for 1 h at 80 °C. 14 This preparation process for synthesizing PUFs is shown in Scheme S1. In contrast, the characteristic peaks derived from the CO and C−O vibration of carboxylic acid were remarkably increased in l-LN.…”

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

“…Acids, bases, alcohols, and other solvents have been explored with varied success. [15][16][17] Water has been used as a solvent at high-temperature, high-pressure (HTHP) conditions. CFRP recycling has been explored in both subcritical (<374 °C) and supercritical water (SCW) environments, which both can be effective at decomposing organic compounds [18][19] and recalcitrant chemicals.…”

“…[29][30][31] Fibers also tend to retain their original shape and tensile strength through chemical recycling. 15,[32][33] Chemical recycling promises the opportunity to recover and re-use the polymer decomposition products, which are captured in the liquid phase. [34][35][36] An improved understanding of promising CFRP chemical recycling conditions, chemistries, and reaction mechanisms is needed to advance the technology toward wider commercial adoption.…”