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 improve the material properties for polypropylene PNCs based on layered silicates by using elongational flow generating devices with super-imposed shear- and elongational flow and optimized nozzle geometries. In order to gain knowledge about the differences in influence for various nozzle geometries, five different hyperbolical and conical nozzles were designed. The varying factors are the nozzle length, the exit radius and the injection speed which correlates with the elongation rate and shear rate. The influence of these parameters was tested for two different materials with a full factorial 2 3 design (DoE). The first material was a lower viscous homopolymer and the second material 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 showed that elongational flow leads to substantial increase in Young’s Modulus especially for the lower viscous homopolymer up to 60 % compared to 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.