Modeling the Formation of Rigid Polyurethane Foams Using Hydrofluorolefin as Expanding Agent

Polyurethanes are probably the most versatile among polymers of greater industrial use due to the possibility of being produced in a wide range of density, hardness, and mechanical properties and through different conversion processes. Its synthesis involves a great variety of raw materials and proportions between them. A mathematical model that describes the polyurethane foam formation can be very useful for the development of formulations and in the definition of the processing conditions, avoiding great consumption of time and errors in the development and experiments. The present work studies this process using industrial formulation. The kinetic parameters of the reaction between polyol with isocyanate are determined calorimetrically using the adiabatic temperature rise method, obtaining the values of activation energy 22.2 kJ mol⁻¹ and heat of reaction 91.8 kJ mol⁻¹. Data liquid–vapor equilibrium of the hydrofluorolefin blowing agent in a polyol mixture are obtained and treated with Flory–Huggins model with good agreement with experimental data (deviation of 1.6%). The mathematical model is satisfactory to describe the expanding process in a pilot scale, under different conditions.