Photocuring of di-acrylate

Photocuring of multi-functional acrylate films for applications in large scale prints and 3D objects is a radical polymerization process under seriously changing conditions of liquid monomer to solid polymer network. Although a model is available describing this process and experimental data have been obtained for photocuring of hexanediol diacrylate (HDDA), measurements with widely varying light intensity to estimate the kinetic parameters in the model were still lacking. We have carried out such measurements with the aim of generating a proper set of parameters for the model, which then may be used for process optimization. We present results of the curing of thin HDDA films (10 μm) with initiator Irgacure 819, bis(acylphosphine oxide) under irradiation intensity varying in a range of 2–1350 W.m⁻². Average conversion of vinyl groups in the films was registered by Fourier Transformed Infrared (FTIR) in transmission mode. A remarkable insensitivity of end conversion (range 78–85%) to light intensity was observed, but conversion rate varied strongly (0.1–6 s⁻¹). Despite the large difference in irradiation and associated macroradical concentration level, a surprising similarity in the shapes of the conversion rate was observed.