Random-Scission Kinetics of Cured Epoxy Resin in Alkaline Sub-CW Based on a Coarse-Grained Network Structure

Recycling carbon fiber reinforced polymers is challenging due to the resistance of their epoxy matrices to chemical degradation. This study investigates the degradation kinetics of diethylenetriamine-cured bisphenol A epoxy resin in KOH-containing alkaline subcritical water at 240–260 °C. Batch experiments show near-complete degradation within 60 min at 260 °C, producing phenolic compounds and acetone, with bisphenol A as a transient intermediate. Molecular dynamics simulations reveal that K+ and OH– ions remain confined to the aqueous phase, supporting a shrinking-core regime controlled at the resin-water interface. A hybrid kinetic model, integrating Monte Carlo random scission on a coarse-grained network and a shrinking-core description, accurately predicts the time and temperature dependence of product distributions. The model yields activation energies of 160.6 kJ mol–1 for glyceryl-phenoxy ether cleavage and 184.8 kJ mol–1 for bisphenol A decomposition. The resin removal end point also corresponds to an apparent optimum in recoverable product value under the present analysis framework.