Cardanol-based epoxy vitrimer/carbon fiber composites with integrated mechanical, self-healing, reprocessable, and welding properties and degradability

Abstract

Thermosetting plastics cannot be reprocessed and recycled due to their permanent and strong covalent cross-linking bonds, and their use could result in serious environmental pollution and resource wastage. An effective strategy to solve the pollution of waste thermosetting plastics is the development of vitrimer materials with integrated mechanical, self-healing, reprocessable, and welding properties and degradability. Herein, two kinds of epoxy vitrimers were prepared using 100% biobased epoxy monomers by introducing dynamic ester bonds through highly efficient esterification and epoxy reactions. The relationship between dynamic ester bonds and the properties of these epoxy vitrimers were systematically explored. Thermal and mechanical properties, chemical degradability, hydrophobicity, dynamic stress relaxation, self-repair ability, shape memory behavior, and weldability were evaluated. The cardanol-based vitrimers had a high glass transition temperature (76.8 °C) and gel content (98.5%) and underwent dynamic transesterification to exhibit programmable self-healing ability, shape memory behavior, and recyclability. The vitrimers were then employed to fabricate carbon fiber composites with high mechanical strength, rapid chemical degradation, and shape memory properties. The products and mechanism of the chemical degradation of the composite were verified by FT-IR (Fourier transform infrared) and gas chromatography–mass spectrometry. This work provides guidance for large-scale industrial preparation and practical application of high-performance biobased vitrimer materials and their carbon fiber composites.