Design and synthesis of an amide-containing crosslinked network based on Diels-Alder chemistry for fully recyclable aramid fabric reinforced composites

Fiber reinforced thermoset composites (FRPCs) have received tremendous attention because of their merits of light weight, high modulus and high strength. However, the efficient recycling of the waste during the manufacturing and service life of FRPCs is still great challenge. This paper reports a newly designed dynamic crosslinked network based on Diels-Alder chemistry as matrix for fully recyclable aramid fabric reinforced composites. The DA network shows good thermomechanical properties owing to the incorporated aromatic amide bonds, and the overall performance can be readily tailored by adjusting the ratio of amide-containing component and flexible aliphatic component. The good reversibility of the DA network and highly efficient recovery of mechanical properties of recycled sample are confirmed. With optimized composition, the DA network exhibits good interfacial strength with aramid fiber that is comparable to that of widely used epoxy resin due to the interfacial hydrogen bonds among amide bonds between fiber and matrix. Moreover, the closed-loop recycling of both matrix and reinforced fabric without any other additive is also demonstrated. This paper presents the first report on recyclable aramid fiber reinforced composites and is expected to provide hints for future development of fully recyclable and high-performance FRPCs.