The Incorporation of Particulate Silica in a Rigid Polyurethane Foam

A commercially available rigid polyurethane foam formulation was modified by addition of increasing quantities of silica fillers of small particle size. The foam products were tested in compression for density and water absorption measurements and were examined by electron scanning microscopy. The reactivity of the fillers to the isocyanate component was examined quantitatively by an infrared technique. The fillers were found to react with the isocyanate component and to cause a collapse of the foam cell structure.