Abstract

This study investigates the feasibility of processing blends of spherical virgin polyethylene terephthalate glycol (PETG) pellets and recycled polyethylene terephthalate (rPET) flakes. The recycled material was obtained from discarded water bottles collected and processed locally. Tensile and flexural specimens were manufactured using different rPET flake sizes and four material compositions: 100% PETG, 30% rPET/70% PETG, 50% rPET/50% PETG and 70% rPET/30% PETG.

The experimental programme included stress-relaxation tests to evaluate viscoelastic behaviour and tensile tests to determine material stiffness and ultimate tensile strength. The results showed that increasing the rPET content led to an increase in the relaxation modulus, while the viscoelasticity ratio remained approximately constant across the different blends. Tensile testing also revealed an increase in stiffness with increasing rPET content, consistent with the relaxation test results. Furthermore, a substantial increase in ultimate tensile strength was observed as the proportion of rPET increased. No clear influence of rPET flake size on the measured properties was identified.

Overall, the findings suggest that locally sourced recycled PET flakes can be incorporated into PETG-based feedstock for FPF, offering a promising approach to reducing plastic waste while potentially improving the mechanical performance of additively manufactured parts.

Keywords

Additive Manufacturing, Recycled PET, Mechanical Properties