Over the last years, the use of nano-reinforced polymers increased due to their superior mechanical, thermal and rheological properties. Polymer nanocomposites (PNCs) which are based on layered silicates feature a higher Young’s-Modulus and increased thermal conductivity. The aim of this study was to increase the material properties for polypropylene PNCs based on layered silicates by using elongational flow generating devices with optimized nozzle geometries, showing super-imposed shear- and elongational flow. In order to gain knowledge about the influence of nozzle geometry on intercalation and exfoliation, five different hyperbolical and conical nozzles were designed. As varying factors the nozzle length, the exit radius and the injection speed, which correlates with elongation rate and shear rate, had been chosen. The influence of these parameters was tested for two different PP grades by means of a full factorial 23 design (DoE). The first PP was a lower viscous homopolymer and the second a higher viscous block copolymer. The influence of the investigated factors on intercalation and exfoliation was checked with SAXS-measurements. The results of the tensile tests (Youngs’s modulus, yield strength) showed that elongational flow leads to substantial increase in Young’s Modulus especially for the lower viscous homopolymer with values up to 60 % compared to the virgin PP. The analysis further showed that best results were achieved with a hyperbolical nozzle providing a low level of elongation and low elongation rate respectively. The measured temperature increase due to viscous dissipation and the additional pressure demand showed much lower values for hyperbolical nozzles compared to conical nozzles. As well long nozzles with high elongation showed a higher pressure demand accompanied with higher melt temperatures. Keywords: Injection molding, Polymer Nanocomposites, Elongational flow.