An efficient and economical degradation strategy for epoxy thermosets based on a low-cost transesterification catalyst

Abstract

Epoxy thermoset materials are widely used in the field of electrical engineering, including gas-insulated enclosed switches and drytype transformers. It is a challenge to degrade and recycle traditional epoxy thermosets, which can lead to serious resource wastage and solid waste pollution. Previously reported strategies have often required harsh chemical conditions or complex chemical syntheses, which cannot effectively recycle and degrade the large amount of existing anhydride-cured epoxy thermoset waste used in electrical engineering. Herein, we propose an efficient and economical degradation strategy for epoxy thermosets based on a commercial transesterification catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene, DBU). DBU is much cheaper than the widely reported transesterification catalyst in the field of degrading and recycling epoxy thermosets (1,5,7-triazabicyclo[4.4.0]dec-5-ene, TBD). We demonstrated that an anhydride-cured epoxy thermoset could be completely depolymerized in DBU-ethylene glycol solution below 140 °C in 2 h (or 120 °C in 3 h). Our study offers an effective method to recycle anhydride-cured epoxy thermoset wastes.