Modulation of cavities and interconnecting pores in manufacturing water blown flexible poly (urethane urea) foams

Flexible poly (urethane urea) (PUU) foam based on the polyol and isocyanate with various additional components is synthesized by one shot polymerization. FTIR analysis shows that both urethane and urea formations are closely related to the catalysts, water, and NCO index. Increment of the catalyst concentration increases the initial volume velocity of the flexible PUU foam but decreases the bulk density by the increased number of cavities and pores. Water has strong effects on the initial volume velocity and bulk density, whereas increment of the NCO index has a little influence on the physical properties. The average cavity and pore sizes increase with increasing the equivalents ratio of water to polyol, but there is a limiting equivalents ratio in the PUU foam systems not to form coalesced or collapsed microcellular structure. The foams are also characterized using a scanning electron microscope and a Fourier transformed infrared spectroscopy.