Rapid stress relaxation and degradable aromatic disulfide vitrimer for recyclable carbon fiber reinforced composite

Abstract Carbon fiber thermoset composites pose significant challenges due to their inability to be reprocessed and the difficulties in recycling carbon fibers. Vitrimer materials with reversible dynamic covalent bonding offer a promising solution for the degradation of thermosetting resins and the recycling of carbon fibers. However, their practical application is limited by inability to quickly release stresses from deformation and long degradation times. To address these limitations, this study presents a novel vitrimer material based on free amine-catalyzed aromatic dynamic disulfide exchange. The dynamic disulfide exchange network, catalyzed by free amines, exhibits rapid stress relaxation, with a relaxation time of only 14 s at 180°C. This exceptional dynamic exchange capability grants the vitrimer material outstanding self-healing properties, shape memory functionality, and recycling performance. Moreover, the higher concentration of disulfide bonds and the generation of small molecules increase the susceptibility of the crosslinked network to thiol degradation, resulting in resin degradation within 5 h. Additionally, this research successfully applies the vitrimer material as a matrix to prepare carbon fiber composites with exceptional mechanical properties. Furthermore, by degrading the resin matrix, effective recycling of carbon fibers is achieved, contributing to sustainable practices in the automotive and aerospace industries.