Sequential nature of the exothermic reactions leading to the formation of flexible polyurethane foams

The exotherms of the reactions leading to the formation of polyurethane foams were measured. The inflection points of the exotherm curves were made evident by continuous differentiation with respect to time. The position and magnitude of the inflection points demonstrated the sequential nature of the reactions. The effects of the functionality of the polyol, the concentrations of the tin and amine catalysts, and the silicone surfactant are discussed.