Hyperbranched polyester catalyzed self-healing bio-based vitrimer for closed-loop recyclable carbon fiber-reinforced polymers

Closed-loop recycling in the matrix resin and carbon fibers (CFs) of carbon fiber-reinforced polymers (CFRPs) is a major challenge. To solve this problem, herein, a closed-loop recyclable vitrimer matrix containing hydroxy-terminated hyperbranched polyesters (HBPs), rosin-derived fumaropimaric acid (FPA), and glycerol triglycidyl ether (GTE) is prepared. The FPA/GTE/HBP vitrimers exhibited excellent mechanical properties owing to the highly reactive hydroxy-terminated HBP and rigid FPA. The abundant hydroxyl groups of HBP catalyzed the dynamic transesterification reaction of the vitrimer network, resulting in self-healing and reprocessing properties. In addition, FPA/GTE/HBP−CF composites exhibited high mechanical strength and interlayer shear strength owing to the presence of HBP. FPA/GTE/HBP15−CF was degraded by ethylene glycol during the catalytic operation of the hydroxy-terminated HBP, and the degraded matrix could be closed-loop recycled. Scanning electron microscopy, Raman analysis, and tensile testing showed that the degradation reaction did not degrade the properties of the recycled CFs. This study presents an environmentally-friendly strategy for preparing closed-loop recyclable CFRPs.