The melt flow behavior is one of the important parameters for additive manufacturing of thermoplastic material, especially for FFF as it can determine the precision and interlayer adhesion of the printed subsequent layers. . The limiting viscosity number is another important key parameter to determine when targeting electrospinning, as it can have direct effect on polymer solution viscosity . The results of the limiting viscosity numbers (Table ) showed lower viscosity for copolymers with lower hard segments content (60 wt%). As the molecular weight of the copolymers with 60 wt% of hard segments was also lower than those with 70 wt%, the viscosity results are in good agreement with the data from the 1 H NMR and GPC (Table ). Additionally, incorporation of PEG 6000 into the copolymer chain reduced the limiting viscosity numbers in both segmental ratios (70-30 and 60-40), as the molecular weight reduced. The presence of PEG 6000, a hydrophilic polymer, can disrupt the intermolecular interactions and increase the mobility of the copolymer chains, leading to lower viscosity thus affecting the fiber diameter. It is reported for example, that under the same electrospinning conditions, higher viscosity can result in higher fiber diameters. By changing the applied voltage during electrospinning, however, the diameter of the fiber can be adjusted.