Recycled PP for 3D printing: material and processing optimization through design of experiment

In this work, blends based on virgin (PP) and recycled (r-PP) polypropylene were designed and formulated, aiming at producing filaments suitable for 3D printing (FDM). A preliminary characterization of PP/r-PP blends at different weight ratios allowed selecting two systems showing adequate rheological behavior for FDM process. The selected blends were melt compounded in a twin-screw extruder, optimizing the processing conditions through a design of experiments approach, involving the use of Taguchi’s method. The blend having the best performance in terms of rheological behavior and thermal characteristics was than selected for the production of the filament and for the subsequent FDM processing. Finally, the mechanical properties and the morphology of 3D-printed samples were also assessed.