Upcycling of Polyethylene Terephthalate Waste into Closed-Loop Recyclable Carbon Fiber-Reinforced Polymer Composites with High Performance

The proper management of polyethylene terephthalate (PET) waste and the development of recyclable carbon fiber-reinforced polymer composites (CFRPCs) are two of the most concerning topics in the field of sustainable polymer chemistry. In this study, we propose an effective strategy that simultaneously addresses these challenges through the upcycling of PET waste into closed-loop recyclable CFRPCs with a high mechanical performance. Specifically, aminolysis products of wasted PET were used as the main building blocks to construct the closed-loop recyclable polymer matrix with judiciously designed dialdehyde moieties and phosphate-based cross-linkers. The matrix exhibited a high tensile stress of about 120 MPa, which is far superior to PET and most close-loop recyclable thermosets reported in the literature. When composited with carbon fibers (CFs), the resulting CFRPCs demonstrated both high tensile strength over 500 MPa and flexural stress over 630 MPa, reaching the practical standard. The matrix can be degraded into its monomers, and CFs can be recycled nondestructively in a solvent-assisted method, which can be reused to fabricate new CFRPCs without significant performance degradation. This research offers a promising paradigm for simultaneously resolving the issues of PET degradation and CFRPC recycling.