Experimental and numerical study on isolated and non-isolated jet behavior through centrifuge spinning system

This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging from a rotating nozzle through centrifuge spinning system. In the centrifugal spinning process, a polymer solution has been pushed by the centrifugal force through small nozzle of a rapidly rotating cylindrical drum. Thereby thin fibers are formed and collected on a collector in the form of a web. Centrifuge spinning suffered from a strong air resistance which leads to a more deflected jet as well as its rapidly solvent evaporation resulting in thicker nanofibers. In this work, centrifuge spinning has been equipped by a rotating collector, whereas the fabrication process was skillfully sealed from ambient airflow. A comparison was drawn between the trajectory of Newtonian liquid jets fabricated by centrifuge spinning and air-sealed centrifuge spinning. The captured images of the liquid jet trajectory using a high speed camera showed that non-isolated liquid jets were more curved than isolated liquid jets due to air resistance. A pre-presented non-linear analysis of the Navier-Stokes equations was carried out and the numerical solutions were compared with the experiments. There was fairly good agreement between the isolated jet trajectory and the model-predicted one, but there were differences between the non-isolated jet trajectory and the simulation results. The non-isolated jet curved more compared to the others due to air drag. Also, the diameter of polymeric nanofibers was predicted and compared with experiments. Some qualitative agreement was found. (C) 2014 Elsevier Ltd. All rights reserved.