Effects of organically modified nanoclay on cellular morphology, tensile properties, and dimensional stability of flexible polyurethane foams

Abstract

Flexible polyurethane/organically modified nanoclay (organoclay) nanocomposite foams were synthesized by a two-step reactive process. X-ray diffraction (XRD), scanning electron microscopy (SEM), and tensile and compression tests have been used in order to investigate clay dispersion, cellular morphology, tensile properties, and dimensional stability, respectively. The XRD patterns of a polyurethane foam sample containing 2 wt.% of nanoclay revealed clay intercalation. Furthermore, SEM images of the prepared foams showed that incorporation of clay into the polyurethane foams results in a reduction of cell size as well as an increase in cell density, and these phenomena were explained on the basis of nucleation promotion in the presence of clay. In addition, tensile modulus of the prepared foams was shown to be improved by incorporation of clay. The results obtained from the compression tests proved that the incorporation of clay into the polyurethane foams leads to deterioration of their dimensional stability. The results obtained from the mechanical studies were interpreted on the basis of physical and chemical interactions between clay surface and polyurethane chains.