Recycling of Epoxy Thermoset and Composites via Good Solvent Assisted and Small Molecules Participated Exchange Reactions

Abstract

Thermosetting polymers and composites are a class of high-performance materials with significant industrial applications. However, recycling of thermosets and their filling matters are significantly challenging. Here, we propose a method to recycle epoxy thermosetting polymer and composites efficiently by a synergistic effect of a solvent mixture using a highly efficient organic catalyst at an ordinary pressure and mild temperatures. The anhydride-epoxy network depolymerization enabled by selective ester bond cleavage process is substantially enhanced by a good solvent assisted and alcohol participated transesterification reaction. The epoxy thermoset can be dissolved in 28 min with 50% mass loss, and 70 min with 95% mass loss at 170 °C under ambient pressure. We demonstrate that this method can be used to reclaim carbon fibers from industrial reinforced epoxy composite products and embedded metal parts from commercial electronic products with undiminished properties at a mild temperature (∼170 °C) under an ordinary pressure in a short time (1.5 h). Moreover, the decomposed epoxy oligomer can be reused as a reactive ingredient for the preparation of new epoxy materials with high strength and modulus. This work provides a new insight into the thermosets dissolution and recycling.