Efficient recycling of carbon fibers from amine-cured CFRP composites under facile condition

Abstract

With an excellent combination of high strength, lightweight, and thermal stability, carbon fiber-reinforced polymer (CFRP) composites are ideal for applications in various demanding fields. The global consumption of CFRP composites continues to increase, and it is estimated that approximately 3000 tonnes of CFRP waste are generated annually. Mostly, the CFRP composites can be classified into two categories: thermoset composites and thermoplastic composites. However, the recycling of industrial thermoset composites is a daunting challenge due to their highly cross-linked thermosetting polymer matrix. In this study, an innovative strategy was developed for recycling amine-cured CFRP composites with a binary alkali catalytic system of monoethanolamine containing 10 wt% potassium hydroxide under facile conditions. The degradation ratio of CFRP composites reached 98.82% after processing at 160 °C in 90 min. The surface of recovered carbon fibers (CFs), as observed by SEM and AFM, appeared smooth, and there was a slight increase in the surface wettability as tested by dynamic contact angle measurements. Furthermore, the use of XPS demonstrated some surface oxidation, while single fiber filament testing suggests a small decrease in the tensile strength of 6.5%.