Effect of chain extenders on the morphology development in flexible polyurethane foam

The effect of chain extenders on the morphology development in flexible polyurethane foam has been studied by small-angle X-ray scattering (SAXS), FTIR spectroscopy, and rheometry. Four chain extenders, diethanolamine (DEOA), 1,2-ethylene diol (EDO), glycerol, and 2-(methylamino)ethanol (ALA-E), were studied in a standard high-resilience (HR) foam formulation. Phase separation was observed to cause the foam modulus rise. On adding chain extenders, the onset of microphase separation was delayed, and the interdomain spacing was increased. This effect strongly depends on the chemical structure of chain extenders and the compatibility between chain extenders and urea segments. The addition of chain extenders to the formulations also delayed the onset of foam modulus growth.