Bio-based epoxy vitrimer for recyclable and carbon fiber reinforced materials: Synthesis and structure-property relationship

Recycling or degradation of epoxy resins is difficult because of their covalent cross-linking structures, which causes resource crisis, environmental pollution, and resource waste. To address this challenge, we reported a recyclable and degradable epoxy vitrimer with dynamic ester bonds prepared from tung oil and diglycidyl ether of bisphenol-A via epoxy-acid-anhydride crosslinking system. Owing to the compact rigid six-member ring and the anhydride structure, the epoxy vitrimer shows high thermal stability, and excellent dynamic mechanical, and mechanical properties with tensile strength of 59.21 ± 1.02 MPa and glass transition temperature of 76.73 °C. The vitrimer network can achieve topological rearrangement via dynamic transesterification reactions with the addition of a Zn catalyst. Thus, the contrivable vitrimer exhibits excellent self-healing, shape memory, and physical recycling at elevated temperatures. Moreover, the epoxy vitrimer matrix has high joining strength with carbon fibers and can be used to prepare carbon-fiber-reinforced materials (CFRMs). The carbon fibers can be completely recycled from CFRMs through an ethanol-NaOH mixture solvent. This work can assist in preparation of degradable high-strength CFRMs using a recyclable tung-oil-based vitrimer matrix and provides a strategy for efficient recycling of carbon fibers from CFRMs.