3D Printing with Recycled PET as a Sustainable Thermoplastic Alternative Comparing Printed and Filament Material Properties

Filament-based 3D printing offers significant advantages but faces sustainability challenges due to its reliance on seldom recycled thermoplastics. Utilizing recycled PET presents a promising sustainable alternative leveraging the global PET recycling infrastructure. This study investigates the feasibility of using rPET for 3D printing filaments by comparing mechanical properties against common commercial filaments (PLA, ABS, and PETG). The paper establishes a baseline by characterizing the tensile properties of the filaments and comparing these to standardized 3D printed specimens in both in-plane and layer adhesion orientations. Results showed a quantifiable loss in mechanical performance between the filament and the printed part across all materials, with XY-axis properties generally showing better correlation to filament properties than Z-axis properties, influenced by interlayer adhesion. PET filaments exhibited modulus values comparable to ABS but lower than PETG and PLA. While PET and rPET demonstrated printability using modern equipment, they showed significant strength reductions in printed form, particularly in the Z-axis, potentially linked to crystallization effects impacting layer bonding. PET lost approximately 30% of modulus strength in the XY-axis, similar to PETG. This work establishes filament testing as a valuable baseline for material comparison independent of printing complexities and furthers rPET's potential as a more sustainable filament option.