Facile in situ preparation of high-performance epoxy vitrimer from renewable resources and its application in nondestructive recyclable carbon fiber composite

Abstract

Epoxy resins have been widely used in several materials including carbon fiber composites; however, they are arduous to recycle. In this study, for the first time, a Schiff base epoxy thermoset combining excellent recyclability and high performance was facilely prepared from a synthesized formyl group-containing vanillin-based monoepoxide and a diamine via in situ formation of the Schiff base structure and epoxy network. The chemical structure of the monoepoxide and its cross-linked network were characterized in detail. In addition, the thermal and mechanical properties, recyclability of the thermoset and its application in carbon fiber composite were systematically investigated. The results showed that the thermoset possessed a similar glass transition temperature of 172 degrees C, a tensile strength of 81 MPa and a modulus of 2112 MPa, and higher thermal stability with the degradation temperature for 5% weight loss of 323 degrees C and elongation at break of 15% in comparison with a bisphenol A epoxy resin. Moreover, it exhibited superior reprocessing recyclability due to the vitrimer or CAN nature of its Schiff base network. Furthermore, it could also be completely degraded under mild acidic conditions, leading to the quick and nondestructive recycling of its carbon fiber composite.