PNNL

Abstract

In recent years researchers have introduced different malleable and/or degradable thermosetting polymers to address the recyclability of traditional thermoset materials, in the literature. Nonetheless, the mechanical properties and glass transition temperature (Tg) of these polymers are often compromised to meet the industrial needs. In this work, a recyclable CFRP with high mechanical performance and high glass transition temperature (Tg > 200 °C) was developed. Triethanolamine is used as the co-curing agent in the epoxy/anhydride curing system to catalyze the curing of the high-performance epoxy resin and to promote the dynamic transesterification reaction with its inherent hydroxyl groups and tertiary amines. The hydrothermal recycling is achieved at relatively low temperature (200 °C) and pressure (~ 230 psi) without the addition of catalyst. This mild recycling process decomposes the recyclable polymer matrix into oligomer and imparts little damages to valuable carbon fiber. Recycled carbon fiber is reused as the reinforcement to prepare new CFRP, and the upcycling of decomposed polymer resin is realized by replacing part of the epoxies in the fresh epoxy resin to also introduce hydrothermal recyclability to the new CFRP.