Viscoelastic Modeling of Stress Relaxation in Model High‐Performance Covalent Adaptable Networks

Establishing structure–property relationships for the reprocessability of high‐performance covalent adaptable networks (CANs) is crucial for facilitating their sustainable use at scale in demanding industries like aerospace and energy. The reprocessing kinetics for a model system of high‐performance CANs (i.e., highly cross‐linked dynamic aromatic disulfide‐containing epoxies) were studied here using a combination of mean‐field theory and stress relaxation experiments at relevant reprocessing temperatures above each material's glass transition temperature ( T g ). The mean‐field theory was found to accurately predict residual stresses in compositions with a percolated permanent structure (i.e., to predict the consequences of insufficient dynamic bonds or undesirable topological placement on effective reprocessing). Through the stress relaxation analysis, it was found that increasing dynamic bond concentration in the epoxies studied here generally resulted in more rapid stress relaxation at elevated temperature and increased relative coupling between stress relaxation and segmental network dynamics.