Environment-friendly recycling of CFRP composites via gentle solvent system at atmospheric pressure

Abstract

The recovery of high-value carbon fibers from carbon fiber-reinforced polymer (CFRP) composites is essential for ensuring a sustainable future. In this work, a simple and eco-friendly approach was presented for the chemical recycling of anhydride-cured epoxy-based CFRP composites with a mixed solution of monoethanolamine (MEA) and potassium hydroxide (KOH). In this solvent catalyst system, the resin matrix was decomposed by cleaving the ester bonds. Thus, a high CFRP composite decomposition ratio of 99% was achieved at ∼160 °C within 60 min under ambient pressure. The recovered carbon fibers (CFs) had a clean surface and retained more than 95% of their original stiffness and strength. Moreover, one of the highlights of this process was that the excess MEA solvent and degraded epoxy resin (DER) were recovered from the degraded organic products (DOP) by simple distillation. The DER was reused in combination with the original epoxy resin system to prepare new resin material with good mechanical properties, forming a closed-loop chemical recycling route. The advantages of this method include facile reaction conditions, near-complete recovery of CFs and solvent, and the absence of harmful solid waste, demonstrating that this recycling process has a high degree of environmental friendliness.