Rising commodity prices and the demand for lighter products always lead to a steadily growing interest in foamed products. On the one hand it is possible to save raw material and on the other hand to obtain very special product properties. The properties of polymeric foams depend on the foam morphology, which means the cell size and cell density, density and the material formulation. The foam morphology may be influenced by the used matrix polymer, type and amount of the used nucleating agent, as well as by the used foaming agent. The aim of this study is to investigate the effect of nucleating agents on the elastic properties and the foaming behaviour of different polymer blends in foam extrusion. For the determination of the viscoelastic behaviour of the polymer melt a special rheological method, so called creep and recovery test, was used. This test gives information about the zero viscosity and the elastic property of the polymer melt. These two parameters have a huge impact on the foamability of the polymer and the cell morphology of the extruded foams. For this study the polymer blends were physically foamed in an extrusion process using supercritical carbon dioxide as blowing agent. The used nucleating agents were different types of talcum. The foamed samples were characterized in terms of density, cell density and mean cell size and compared with each other. The determination of the density was carried out according to Archimedes’ principle. For the characterization of the cell size light microscope images of cross-sectional areas of the extruded foam samples were made.