Electrostatic characterization of electrohydrodynamic atomization process for polymeric particle fabrication
Advancing the chemical engineering fundamentals
Particulate Systems (T2-3)
Keywords: microparticle, electrohydrodynamic atomization, electrostatics, fabrication
The electrostatics of electrohydrodynamic atomization (EHDA) process in a shuttle-chamber for polymeric particle fabrication was, for the first time, investigated. The electrical potential field between the spray nozzle and the ground plate inside the chamber was measured three-dimensionally and demonstrated that the electrical field strength increased with decreasing nozzle-plate distance and the variation became significant in the region closed to the nozzle where liquid spray occurred. It is deduced that the nozzle-plate distance may affect liquid spray significantly. Four liquids, two inorganic liquids (water, KCl) and two organic liquids (PLGA+DCM (w/v=7%), PLGA +Acetonitrile (w/v=8%)) were tested and the organic liquids were sprayed to fabricate micro-particles. For spraying inorganic liquids the currents scaling was I ~ Q^1/2 but for spraying organic liquids the currents scaling was I ~ Q^1/4. The accuracy of current scaling depended on the values of δμδ^1/3, which was independent of the nozzle-plate distances (electric field strength). In addition, the spray current increased with decreasing nozzle-plate distance (or increasing liquid flow rate or liquid conductivity). As a result of spraying polymer solution with volatile organic solvent, particles with size of 0.61~36.10µm were fabricated. Particle size decreased with decreasing nozzle-plate distance as well as increasing conductivity of polymer solution or decreasing the liquid flow rate. For all cases of particle fabrication, Rayleigh limit was never reached and no coulomb fission occurred in the experiments.
Presented Monday 17, 16:00 to 16:20, in session Particulate Systems (T2-3).
