Comparison of the Mechanical Properties of 3D-Printed Materials PET–G and rPET–G

The use of recycled polymers in additive manufacturing has emerged as a promising strategy for reducing the environmental impact of polymer processing. However, the influence of recycling on monotonic and fatigue properties of polymeric materials manufactured by fused deposition modelling (FDM) is not yet completely understood. This paper compares the monotonic and fatigue properties of virgin PET–G and recycled PET–G (rPET–G) specimens manufactured via FDM using commercial filaments supplied by the same manufacturer. Monotonic tensile tests were conducted under uniaxial quasi-static loading conditions, while fatigue tests were performed under rotating bending with constant amplitude and load-controlled conditions. Fatigue fracture surfaces were analysed using scanning electron microscopy to identify the main failure micromechanisms. The results revealed a reduction in the tensile strength of rPET–G compared with the virgin PET–G, which agrees with the trends reported in the literature. However, only a relatively small difference was observed in the fatigue strength. For a fatigue life of 105 cycles, the recycled material exhibited reductions of 6.5% at a 50% probability failure and 1.9% at a 5% probability failure relative to the virgin material. This behaviour was associated with the presence of voids, which were more numerous in the rPET–G.