Numerical simulation to correlate photopolymerization kinetics monitoring by RT-NIR spectroscopy and photocalorimetry

Photocalorimetry (DSC) and real time infrared (RTIR) spectroscopy are the two usual methods used to follow photopolymerization reactions. Kinetics obtained by DSC on thin samples and kinetics obtained by real time near-infrared (RT-NIR) spectroscopy on thick samples are not the same. The heat release during the photopolymerization induced a high temperature increase in thick samples because of the absence of temperature control. We think that this temperature offset is the main cause of this kinetic difference. In this paper, we want to verify this assumption. To reach this aim, conversion and temperature evolutions versus time were numerically simulated for a sample placed in the thermal conditions of NIR analysis by using experimental kinetic data obtained by photocalorimetry in isothermal mode. The boundary conditions were determined such as the simulated evolution of the sample temperature is the same as the experimental one. At last, conversion curves simulated to obtain these temperature profiles were compared to experimental results obtained by RT-NIR.