Morphological/alignment properties of thermoplastic polyurethane nanofiber affected by processing parameters

Thermoplastic polyurethane (TPU) in nanofiber or submicron fiber has widespread application areas including the biomedical applications, such as artificial vein, cell cultivation etc. due to both TPU’s and nanofiber’s morphological properties. The morphology and aligment of nanofibers obtained from electrospinning are significantly affected by process parameters, which affect their end uses. This study aims to investigate the effect of process parameters of electrospinning (nozzle axis type, collector type, collector speed and filler types) on morphological properties (fiber orientation, fiber diameter and porous structure) of thermoplastic polyurethanes. Experimental results showed that nanofiber diameter increased with an increase of collector speed due to the relaxation of extensible TPU nanofiber after spinning process. When the rotational speed of collector reaches to 2000 rpm, the orientation could be observed. Using rotational wire collector resulted in thinner and more oriented fibers compared to rotating cylinder collector. Adding salt particles results in thinnest and highly oriented nanofiber webs. Higly porous surfaces were obtained using coaxial technique at the same feeding rates with miscible solvents for both shell and core. It was seen that using solvent with low boiling point in core may lead to higher porous surfaces. Nanofiber diameter increased using coaxial nozzle instead of single axis nozzle.