Reconstruction of new high-performance epoxy thermoset based on the full utilization of the degradation products of waste epoxy thermoset

Chemcycling of waste plastics seeks high-efficiency degradation and high utilization of degradation products. However, it is difficult to achieve such a goal for epoxy thermosets due to their dense network structure and lack of active groups in degradation products. In most cases, only a small fraction of the degradation products can be used to reconstruct new epoxy thermosets after waste epoxy thermosets are degraded which accounts for a very low proportion in the new epoxy thermoset. Herein, we report a chemical upcycling of waste anhydride-cured epoxy thermosets to new epoxy thermosets based on the degradation-modification-reconstruction strategy. The epoxy thermoset is degraded using a simple and efficient alkali/alcohol system with the yields of about 90 % of two degradation products. The two degradation products are further modified into new epoxy monomer and curing agent respectively. All the modified products are directly used to prepare new epoxy thermosets with high performance without additional epoxy monomer or curing agent added. This work realizes the full utilization of the degradation products of waste epoxy thermoset, and the degradation products account for more than 80 % of the new epoxy thermoset. Carbon footprint and economic calculations show that the strategy is environmentalfriendly and cost efficient.

Automated summary

Chemcycling of waste plastics aims to achieve efficient degradation and utilization of degradation products. This study presents a chemical upcycling strategy for waste anhydride-cured epoxy thermosets, where the thermosets are degraded using an alkali/alcohol system to obtain two degradation products with a yield of about 90%. These products are then modified into new epoxy monomer and curing agent, directly used for preparing high-performance epoxy thermosets. The degradation products account for more than 80% of the new epoxy thermoset.