Effects of polypropylene compositions and processing conditions on its aging resistance under tropical environments

This study investigates the weathering resistance of three polypropylene grades (impact-resistant, recycled and UV-stabilized) processed by Fused Filament Fabrication (FFF), injection and thermo-compression. Samples undergo accelerated aging, simulating conditions equivalent to six months in tropical environments with high hydrothermal and UV exposures. They are characterized by chemical, thermal, rheological, mechanical and microstructural analyses. 3D-printed impact-resistant and UV-stabilized PP resist to the considered aging conditions, attributed to the presence of stabilizers. On the contrary, the properties of recycled PP deteriorate over time due to low stabilizer concentration and the presence of impurities post-recycling. Samples processed by thermo-compression and injection display lower aging resistance compared to their 3D-printed counterparts, due to degradation and alteration in the crystalline structure induced by the processing method, like the 'skin effect' observed in injection. These findings highlight the importance of re-stabilization during recycling and the potential of 3D-printing for enhancing the aging resistance of polypropylene.