Modeling Thermal and Optical Effects on Photopolymerization Systems

A comprehensive photopolymerization model that incorporates heat and mass transfer effects, diffusion-controlled propagation and termination, and temporal and spatial variation of species concentration, temperature, and light intensity is applied to systems with varying thermal and optical properties. The absorbance of the polymerizing system is varied by altering either the initiator concentration, sample thickness, or molar absorption coefficient of the initiator. Simulations show that the choice of initiator and sample thickness limits the initiator concentration usable to achieve complete conversion in a sample. Similarly, the initiator and its concentration should independently be chosen since each impact the polymerization differently. Three different thermal boundary conditions and their effects on polymerization are also considered. These boundary conditions include isothermal, perfectly insulating, and perfectly conducting. Simulations show that a higher absorbance sample polymerizes completely when perfectly insulating boundary conditions are assumed. Thus, it was found that the choice of initiator and its concentration should be determined not only from the desired film thickness but also considering the thermal conditions that affect the sample during photopolymerization.