Impact of Mass Transfer Limitation of Polyurethane Reactions

摘要

During urethane reactions, large changes in viscosity lead to large changes in mass transfer rates. After the gel point, the mass transfer of blowing agents from the gel to cells essentially ceases; however, mass transfer for reactions continues, albeit at a slower rate. This poster is on fundamental approaches to account for the impact of these changes in mass transfer on reaction rates. Three different approaches were studied to describe the rate of molecular movement of the reactive moieties during polyurethane reaction. Inter- and intra-molecular movements of moieties where studied as a separate diffusion steps. Inter-molecular movement stops at the gel point and intra-molecular movement has been added to describe moieties movement after the gel point. The collision frequency factor in Arrhenius equation was modified based on inter- and intra-molecular approaches. Simulation results for reaction temperature and viscosity profiles show good agreement with the experimental data.