Foaming parameter identification of polyurethane using FOAMAT® device

International audienceA key problem in the modeling of polyurethane foaming is the determination of relevant physical parameters for the viscosity, the gas expansion and the curing rate. Indeed, it is difficult to measure the chemical kinetics parameters as well as the viscosity of industrial polyurethane formulations (polyol-isocyanate-water mixture) because the time scales of gas production and polyurethane crosslinking are very short and hardly compatible with the installation of the sample in characterization devices such as DSC and parallel plates rheometer. A FOAMAT® system has been developed to get these experimental data but the relationship between measurements and rheo-chemical parameters has not been clearly established. In our approach an analytical model of the foaming process is developed in the cylindrical FOAMAT® geometry which allows identifying the parameters of the curing and gas production kinetics equations, as well as the viscosity. As a consequence, one exhibits new modeling equations [2] for polyurethane foaming which can be fully identified with this FOAMAT® device. This analytical model is based on a set of simplifying hypotheses which validity is checked using the finite element computation software REM3D® dedicated to foaming modelling and applicable for injection-molding processing. Furthermore, an analysis of the influence of viscosity modeling on foaming simulation has been performed