Recycling Waste from Film Packaging to 3D Printing Applications: a Prospective Study to Identify the Processing Temperature

This study was devoted to promote eco-friendly processes and products in film packaging and 3D printer industries though sustainable and biodegradable resources, circular economy approach and recycling operation. A commercial bio-based filament, obtained by recycling of biobags, has been considered. An initial rheological characterization consisting both in dynamic (i.e., time sweep, frequency sweep) and transient (i.e., stress relaxation) mode testing, was conducted on pelletized recycled material. The complex viscosity trend over time at different testing temperatures (210°C, 190°C, 170°C) allowed to attest the polymer thermal stability as function of testing temperature. The shear modulus against time at different testing temperatures (130, 150, 170°C, and 210°C) provided information on the minimum temperature of extruded melted polymer, deposited on the printer platform, to ensure adhesion between layers. The storage and loss modulus vs oscillation frequency from 130°C to 170°C allowed to identify the temperature at which viscous behaviour of the processed material could be guaranteed during the extrusion process. Then, attempts to print the recycled polymer were carried out at 180°C, 190°C, 210°C, respectively. Finally, thermo-mechanical characteristics of 3D specimens, printed at 190 and 210°C, have been compared in terms of storage modulus and dissipation factors.