PSI - Issue 56

Sergiu-Valentin Galațanu et al. / Procedia Structural Integrity 56 (2024) 138– 143 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction In the last decade, 3D printing technology using Additive Manufacturing (AM) technology, became more and more popular, due to the various industrial applications in the field of rapid manufacturing to fabricate prototypes and concept models. It has several benefits like simpler and reduced supply chain, increased longevity of the product, eradication of tooling need, and shorter assembly chains according to Krishna et al. (2021) and also provides design freedom to the product designer and makes the product more sustainable, Vashi et al. (2021). Fused deposition modelling (FDM), which is perhaps the most used AM techniques by materials engineers and hobbyists alike, involves the extrusion of a molten filament through a heated nozzle onto a build plate to form a part, which is subsequently built up layer by layer until a finished printed product is completed, Holcomb et al. (2022). Polyethylene terephthalate glycol (PETG) is an amorphous polymer widely used in 3D printing which performs well mechanically and is far less brittle compared to polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) (124% elongation at fracture vs. 6% and 100%, respectively). Also, compared to the semi-crystalline polyamide printing polymers, the amorphous PETG shows a lower thermal shrinkage after printing, leading to reduced warping of the printed parts, Rijckaert et al (2022). A wide range of thermoplastic filaments like PLA, ABS, and PETG are used as a filament in 3D printing according to Ngo et al. (2018), which are non-biodegradable, thus the waste aspect of 3D printed plastic products is a matter of concern due to its impact on the circular economy. Zhu et al. (2021) shown that in order to incorporate sustainability into the process, to minimize negative environmental impact, “the choice of filament -type has an important role in the circular economy of filaments”. Popa et al. (2022, 2023) investigated the impact energy and the impact strength on PLA and PETG specimens, obtained through FDM technology. Studies have been conducted in order to obtain recycled 3D printed PETG models with high mechanical properties. Schneevogt et al. (2021) shown that a 100% recycled PET (rePET) filament is compared to a conventional PETG filament; tensile tests are furthermore conducted on specimens made from a conventional polymer material and a recycled polymer material. Another study describing the process of printing with 100% recycled PETG using fused FGF (fused granule fabrication) methods examines the extent to which PETG can be recycled and reprinted through the same FGF tool without significant loss to its material properties, Thompson et al. (2022). Kovácová et al. (2020) tried to replace commercial virgin PETG with cheaper recycled PETG whose price is ten times lower, using composite materials for 3D printing technology by FFF (fused filament fabrication), and concluded that replacing virgin PETG with recycled PETG does not significantly change the properties of the filament, just causes a price reduction. Furthermore, research showed that it was possible to recycle and reuse PETG material multiple times, resulting in a significant gain in the mechanical properties of the recycled materials Vidakis et al. (2021). In this study, we investigated the mechanical properties of raw and recycled PETG materials. The Dantec Digital Image Correlation (DIC) 3D was used to measure the deformation of the specimens in the time of tensile test for a better understanding of their behavior. A good correlation between the results obtained using the raw material and the recycled PETG material was observed. If compute the difference between the movement of the upper and lower point from the specimen in DIC, the maximum displacement in the recycled specimen is 1,39mm and 1,28mm for the raw specimen respectively until the crack appears. 2. Materials and Methods In the framework of this study, tensile tests were carried out on various specimens. The specimens were manufactured using Prusa MK3 printer. Fused deposit modeling technology, with different colors of the filament: colorless, black, and white, but also filament extruded from recycled pellets, were used. For the extrusion of the recycled grains into a filament, used in fused deposition modeling (FDM) technology, a Felfil evo filament extruder was used, Figure 1 a. The recycled filament was extruded from polyethylene terephthalate glycol (PETG) at a temperature of 195°C and with a speed of 7 rpm according to the manufacturer's requirements. In order to observe the geometric characteristics of the new extruded filament, the diameter of the wire was measured as follows: from 10 to 10 cm in length, Figure 1b.