Effect of scattering nanoparticles on the curing behavior and conversion gradient of UV-curable turbid systems: two-flux Kubelka-Munk approach

UV-curable systems based on polyethylene glycol diacrylate (PEG-DA) containing various amounts of scattering silicon nitride nanoparticles were studied by real-time Fourier transform infrared (RT FTIR) and real-time UV-visible (RT UV-visible) spectroscopies. Increasing the percentage of nanoparticles into the UV-curable systems caused the photopolymerization rate and final double-bond conversion to increase. Principal component analysis (PCA) was applied to transmission spectra of samples with various amounts of nanoparticles. Results showed a significant correlation between the two most important principal components and the absorption and scattering phenomena. Absorption and scattering coefficients were evaluated from the reconstructed data using a two-flux Kubelka-Munk theory and radiative flux behavior was calculated. Conversion gradients inside a thick layer were simulated using the radiative flux and curing kinetics experimental values. Finally, the effect of scattering particles on the curing depth was studied.