Clay filled rigid polyruethane foam

Abstract

Rigid polyurethane foams were prepared from a commercial system using clay as filler (0, 5, 10 and 20 wt.%). The effect of foaming process on the dispersion of clay in the polymeric matrix and their consequences on the physical properties of the final foams were investigated. The better dispersion of the clay was observed in the sample containing 5 wt% of clay by means of X-ray diffraction analysis and transmission electron microscopy (TEM). However, TEM photographs showed that in all the composites the clay layers were dispersed heterogeneously in the polymeric matrix. Regions with agglomerates, intercalation of the polymeric chain in the clay galleries and small amount of exfoliated clay sheets were observed. Also the analysis by TEM showed a slight alignment of silicate layers as a result of biaxial flow during the foaming process. The filled foams were characterized and the compressive properties were determined. The modulus and compressive strength showed a maximum for a clay content of 5 wt.%. However, an improvement in the thermal stability with the clay content was not observed.