Recyclable flame-retardant epoxy thermosets and composites: chemical concepts and future prespectives

The presence of cross-linked networks, flame retardants, or other functional molecules makes the recycling of nonhalogenated flame retardant (NHFR) epoxy thermosets (ETs) very challenging. The use of fire-safe epoxy-based materials in a variety of applications has increased in the past few decades, together with the demand for their recycling. To address this issue, next-generation thermosets with inherent fire resistance and recyclability are being designed. Recyclable epoxy materials containing covalent adaptable networks are paving the way to energy-efficient and more sustainable recycling technologies, where recyclability is considered during material design and fabrication. Recent developments in the reuse and recycling of NHFR ETs are presented here. In addition to fire-safe applications, recovery strategies and challenges for the polymeric matrix and valuable fibers from fiber-reinforced polymer composites are described.