Polymer Engineering and Science, Vol.61, No.4, 1243-1256, 2021
Foaming parameter identification of polyurethane using FOAMAT (R) device
A key problem in the modeling of polyurethane (PU) 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 PU formulations (polyol-isocyanate-water mixture) because the time scales of gas production and PU crosslinking are very short and hardly compatible with the installation of the sample in characterization devices such as differential scanning calorimetry and parallel plates rheometer. A FOAMAT (R) system has been developed to get these experimental data but the relationship between measurements and the rheo-chemical parameters has not been clearly established. In this paper, 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. 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 modeling and applicable for injection-molding processing.