# Research on Basic Properties of Polymers for Fused Deposition Modelling Technology
## 2 Materials and Methods  
### Characteristics of Printed Materials  
The research included a set of materials including thermoplastics intended for additive printing using FDM technology. FDM (Fused Deposition Modeling) is a method that involves applying a thermoplastic material layer by layer, after which the filament is heatedin the so-called extruder and is then applied in layers using a head. These materials differed in terms of their physical parameters. Each sample had 5 upper and lower compact layers, 5 outlines, and 100% fill. The printing speed was unified for each type of sample filling and was 30 mm/s. The layer height was 0.2 mm. The extrusion temperature of each filament was selected individually according to the material properties. Table 1 contains detailed information on the selected types of filaments, along with data on their mechanical properties as provided by the manufacturers. Material samples were prepared for printing using the original Prusa MKIV printer (Prague, Czech Republic, PrusaResearch). The materials used in the study were selected by distinguishing their properties. Materials such as FiberFlex and TPU exhibit flexible behavior, while PLA, PETG, HIPS, and PA exhibit brittle properties. By examining their properties and then comparing them, it is possible to estimate the appropriate application for each of these materials. Materials with carbon fiber additives demonstrated high stiffness, with optimal results achieved under carefully controlled extrusion and bed temperatures to address surface roughness and material detachment issues [36; 37]. Flexible filaments posed challenges such as nozzle clogging and excessive flow; however, reducing the extrusion temperatures improved smoothness and dimensional accuracy [29]. Thermoplastics like HIPS required specific adjustments to counteract material contractions and brittleness, with modifications such as increased bed temperatures and fan cooling adjustments yielding consistent, smooth prints [30]. TPU, characterized by abrasion resistance and low shrinkage, provided highly precise and flexible prints under recommended conditions, while polyamide-based composites reinforced with carbon fibers offered uniform layer distribution when printed at high temperatures [31]. Widely used materials like PLA and PETG required relatively standard conditions, producing consistent results with smooth surfaces and no dimensional deviations. The findings underline the importance of optimizing printing parameters for each material to achieve desirable properties, contributing valuable insights into enhancing FDM print performance. Before fabricating the final test specimens, preliminary experiments were conducted to determine the optimal printing temperatures for extrusion and bed heating, both of which play a crucial role in ensuring print quality and mechanical performance. The optimization process involved producing calibration samples with dimensions of 20 \(\times\) 20 mm and a height of 15 mm (Figure 1). These calibration prints were systematically evaluated for their surface finish, dimensional accuracy, and structural integrity to identify the temperature settings that yielded the best extrusion parameters. For extrusion temperatures, the focus was on eliminating common printing defects such as stringing, delamination between layers, and deformation caused by detachment from the heated bed. The analysis involved observing the material's flow consistency, layer adhesion, and overall structural quality. The optimal extrusion temperature was defined as the temperature at which the filament exhibited smooth flow, strong interlayer bonding, and minimal visual defects. Bed heating temperatures were equally critical to ensure proper adhesion between the printed layers