Measurement and prediction of polymerization residual stress evolution under UV intensity from 10 to 30 mW/cm²

Abstract

Although the correlation between monomer conversion and residual stress in photopolymerization has been widely studied, a fully predictive numerical model grounded in a complete theoretical framework remains lacking. Residual stress accumulated during curing can significantly compromise the mechanical and dimensional stability of UV curable resin. In this study, a coupled chemo-mechanical model was developed to predict residual stress evolution in UV-curable systems, incorporating key subprocesses such as polymerization kinetic, volume shrinkage, gelation, and residual stress development. Kinetic parameters were optimized using a genetic algorithm (GA) based on experimental data, and validated through real-time FT-IR and photo-rheometer. Without empirical fitting, the model accurately predicts stress evolution under specific irradiation conditions where the system approaches quasi-equilibrium. However, it fails to capture stress behavior in early non-equilibrium or post-vitrification elastic-dominated stages. Incorporating empirical equation improves global prediction accuracy, especially in the mid-to-late curing stages, but increase deviation at low intensity and short irradiation times. These results highlight the trade-off between general applicability and local accuracy in stress modeling.