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

## TL;DR

This study explores a new method to recycle thermoset polymers using a continuous extrusion process that could replace energy-intensive ball milling.

## Contribution

The study introduces solid-state shear extrusion as a scalable, energy-efficient alternative to ball milling for thermoset recycling.

## Key findings

- SSSE vitrimers maintain over 80% of their mechanical properties after multiple reprocessing cycles.
- The activation energy and mechanical properties of SSSE vitrimers are comparable to those produced via ball milling.
- Metal-carboxylate ligands formed during SSSE enable robust, recyclable vitrimer networks.

## Abstract

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.

Vitrimerization converts permanent thermoset networks into dynamic covalent ones (vitrimers) that can be reshaped and recycled. Solid‐state shear vitrimerization via extrusion (SSSE) offers a continuous, ambient‐temperature alternative to high‐energy batch ball milling: metal‐carboxylates ligands formed during SSSE serve as junctions for the transesterification exchange reaction during subsequent compression molding, building a robust, recyclable vitrimer network.