PSI - Issue 56

Mina Šibalić et al. / Procedia Structural Integrity 56 (2024) 78–81 Mina Šibalić/ Structural Integrity Procedia 00 (201 9 ) 000 – 000

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as one of the earliest 3D printing techniques, involving the extrusion and fusion of materials through a nozzle to construct three-dimensional objects. Typically, FDM leverages polymer-based filaments, with PLA, PETG, and ABS being the most prevalent choices, rendering PVA an unconventional option for FDM printing. Consequently, this research aims to lay the foundation for enhancing the suitability of PVA material for FDM printing. PVA material boasts versatility and finds extensive applications, particularly in the fields of medicine and agriculture (Li, H. et al., 2020). Use of PVA material in medical applications, more precisely in the pharmaceutical industry, since the CAD design ensures the opportunity to add drug-releasing holes into the surface of the carrier, produced from PVA material (Basa B, et al., 2021). PVA is characterized by its hydrophilic nature and exhibits a semi-crystalline planar zig-zag structure (Khoramabadi, N. et al., 2020). Furthermore, PVA demonstrates exceptional chemical and thermal stability, resisting degradation within most physiological settings. Its water-soluble properties, enhanced polarity, non-toxicity, and high biocompatibility render it easily workable. PVA material holds great promise for crafting biodegradable films, though its water-solubility remains a challenge in FDM printing, except in specific cases involving dual-head printers where PVA serves as a support material. As highlighted in the abstract, this paper’s objective is to assess FDM-printed PVA specimens to determine the maximum force threshold. These findings are poised to significantly influence future research endeavors, potentially leading to the development of new bio-polymers derived from PVA material. In the course of printing test specimens, adjustments were made to the layer thickness, while maintaining constant parameters such as the head and bed temperatures, as well as the specimen’s orientation. Table 1. Show the printing parameters that were pre-set in the software, which include printing velocity, bed temperature, and head temperature.

Table 1. Pre-defined parameters. Head temperature (֯C)

Bed temperature (֯C)

Specimen orientation

Printing speed (mm/s)

210 210 210

30 30 30

90 ֯ 90 ֯ 90 ֯

30 30 30

Table 2. shows the defined values for variable parameters for each number of test parameters.

Table 2. Variable parameters for each number of tests. Number of tests

Layer height ( mm )

1 2 3

0.1

0.15

0.2

2. Specimen preparation The PVA material’s susceptibility to instability during FDM printing is evident through increased moisture absorption when exposed to the air for extended periods, resulting in altered mechanical properties. To mitigate this, the material was consistently maintained under similar conditions throughout the testing process. During printing, the filament was stored in a Polybox to maintain a controlled atmosphere. Overnight, the material was subjected to drying at a temperature of 40 degrees Celsius between 6 p.m. and 7:30 a.m. ( Šibalić, 2022 ). The specimens were printed according to the ISO 527-1:2019 standard, orientation remained consistent to ensure accurate testing, with a focus on determining the maximum force required for the specimen layers to delaminate. As illustrated in Figure 1, the specimens were 3D printed with their layers aligned parallel to the printing bed (the only printing angle that was considered for the testing is 0 ° ). Layer separation, which was observed in this research, referred to as delamination, is a 3D printing issue involving poor layer adhesion.