Elaboration of polypropylene/carbon nanotubes by twin-screw mixer and identification of rheological behavior

This paper focuses on the numerical simulation of the mixing stage of injection molding process, for polypropylene/multi-walled carbon nanotube (PP/MWCNT) nanocomposites. First, a twin-screw mixer had been employed for preparing polypropylene nanocomposites loaded at 2, 5, and 10 wt% of MWCNT. Then, a characterization of rheological behavior for polypropylene as well as polypropylene/multi-walled carbon nanotube mixtures, at three temperatures (180, 200, and 220 °C,) has been carried out using capillary rheometer, in order to build a consistent flow model. The second part of the paper concerns the design of a transparent front wall for the twin-screw mixer in order to measure the temperature field for the PP in the twin-screw mixer cavity using infrared camera with high-quality thermal imaging. The final part is mainly devoted to the modeling of the polymer-filler flow during the mixing stage using the finite element method. Both PP and MWCNT have been mixed by using a twin-screw mixer. A proper agreement between numerical simulation and experimental results concerning mixing torque and mixing index as well as temperature fields has been obtained.