The Basic Polyurethane Foam Chemical Reaction
Actually two chemical reactions, TDI (Toluene Diisocyanate) is central to both. Polyol (short for polyfunctional alcohol) combined with TDI creates elastomeric urethane. The combination of water and TDI produces CO2 gas. This reaction is exothermic. These two reactions taking place simultaneously produce foam. Polyurethane foam is nothing more than urethane with bubbles in it. The French call it mousse.