Recovery of epoxy thermosets and their composites

As the currently predominant thermoset plastic, epoxy thermoset is widely used in composite materials, electronic packaging materials, coatings and adhesives. The rapid rise in epoxy thermoset composite materials used for wind turbine blades is largely driven by increasing consumer demands for new energy sources such as wind power in the world. The recovery of the thermosetting polymers is among the most pressing contemporary challenges with the massive decommissioning of the materials. The review summarizes the recent advances on the recovery of epoxy thermosets from two different strategies including source-based recovery strategy (SRS, rational design of recyclable thermosets) and end-based recovery strategy (ERS, recovery approaches of existing thermosets). The recovery methods based on ERS are thoroughly discussed towards physcycling and chemcycling. We highlight important but easily neglected issues during the chemcycling, including mass transfer and heat transfer, solvent effects, full use of both reinforced materials and epoxy thermosets, as well as upcycling. It was pointed out that application-oriented chemcycling should be developed based on selective degradation and effective reconstruction. Finally, this review presents the forthcoming challenges and the prospects for future development.