Influence of print speed on the microstructure, morphology, and mechanical properties of 3D-printed PETG products

The presented research aimed to thoroughly investigate the effects of print speed on glycol-modified poly-ethylene terephthalate (PETG) printed using fused filament fabrication (FFF) technology. The printed product microstructure and morphology were evaluated by a scanning electron microscope (SEM), a surface roughness tester, and an X-ray microtomograph (microCT). Higher print speeds give rise to voids and other morphological defects inside the printed product and on its surface. Print speed also has a considerable impact on the surface profile and pores present inside the samples. A non-monotonic dependence of polymer chain orientation on print speed was found using polarized Raman spectroscopy but is unlikely to play an important role in forming the voids on the surface. Some micromechanical properties (Vickers microhardness, Young's modulus, the work of indentation) slightly depend on the print speed. Potential relationships between the micromechanical properties and the polymer chain orientation were observed too. Besides a detailed characterization of the printed products, various mechanisms involved in the printing process and affecting the final product properties are discussed too. Print speeds up to 60 mm s-1 were identified as suitable for our PETG samples.