Accounting for spatial variations during photopolymerization of 1,6‐hexane‐diol diacrylate in the presence of oxygen

Abstract

AbstractA dynamic model is proposed for photopolymerization of 1,6‐hexane‐diol diacrylate (HDDA) with bifunctional initiator bis‐acylphosphine oxide (BAPO) in the presence of oxygen. This partial‐differential‐equation model predicts time and spatially varying vinyl‐group conversion as well as concentrations of monomer, initiator, oxygen, and seven types of radicals. Experiments to obtain diffusivities of oxygen, BAPO and HDDA are reported. Oxygen‐related parameters are estimated using real‐time Fourier‐transform infrared (FTIR) conversion data. FTIR experiments were conducted using a range of film thicknesses (), BAPO levels () and light intensities (). The model predicts qualitative trends. Conversion predictions for runs with high intensities () and high BAPO () are accurate with a root‐mean‐squared error (RMSE) of 0.04. Larger RMSE (0.13) for runs with lower intensities and BAPO indicates that improved parameter estimates are required. Parameter estimates will be updated in future using a model that accounts for shrinkage during polymerization.