Injection of thermoset foam: comparison between simulation and experiment

The quality (cellular homogeneity, mechanical properties) of polyurethane foam’s structures mainly depends on the manufacturing process, during which two concomitant (principal) exothermic chemical reactions take place: the first one creates CO2 into the fluid matrix (germination of bubbles, expansion and coarsening of the foam) and the second one leads to the polymerization. In order to validate a model developed at CEMEF, an original experiment (RheoFoam System) has been created. It consists in an instrumented injection mould (closed or opened cylindrical cavity) in which the viscoelastic foam inflates. It allows measuring simultaneously the evolution of some technological parameters (the rise of the foam, the pressure distribution on the bottom of the mould and the temperature evolution inside the foam) which are a macroscopic signature of the evolution of the cellular microstructure. These temperature and pressure fields are then compared to those obtained using the numerical simulation. The results are discussed.