Modeling of 1,6‐Hexanediol Diacrylate Photopolymerization with Spatial Gradients and Film Shrinkage

A dynamic model is proposed to account for shrinkage and swelling during the photopolymerization of 1,6‐hexanediol diacrylate (HDDA) with the bifunctional initiator bis‐acylphosphine oxide (BAPO) in the presence of oxygen. The model is composed of 14 partial differential equations (PDEs) that are used to track changes in film thickness along with time‐ and spatially‐varying concentrations of monomer, initiator, oxygen, pendant vinyl groups, and seven types of radicals. Shrinkage has a noticeable influence on the model predictions. For a variety of simulated photopolymerization experiments, there is ≈9% discrepancy between predicted overall vinyl‐group conversions obtained from the current model with shrinkage and a previous model without. Prediction discrepancies become larger for simulated experiments involving thin films (8 µm) or low light intensities (1200 W m −2 ). In the future, it will be important to re‐estimate the kinetic parameters used in the shrinkage model to obtain accurate model predictions for use in process improvement studies.