Recycling Thermoset Systems by Vitrimerization Using Solid-State Shear Extrusion- A Feasibility Study

Thermoset polymers with permanently cross-linked networks have outstanding mechanical properties but cannot be reprocessed or recycled. Vitrimerization is a simple and practical method to convert permanent crosslinked thermosets into vitrimers with covalent adaptable networks, which can be recycled. Vitrimerization is a mechanochemical strategy to convert thermosets into vitrimers by using a ball milling system. In this study, we propose solid-state shear extrusion (SSSE) as a continuous, room-temperature route to replace ball milling (BM) for epoxy vitrimerization. The vitrimerized thermosets obtained using the SSSE process exhibit comparable activation energy and mechanical properties with the vitrimers obtained using the BM method. In addition, the SSSE vitrimers can be reprocessed multiple times, maintaining above 80 percent in mechanical properties. This first feasibility study of employing SSSE for vitrimerization may establish it as a scalable, energy-efficient alternative to batch BM for industrial, closed-loop recycling of thermosets with the least environmental impact.