(395e) Nanofiber Structure Influenced by Air Gap In a Collector Plate of Electrospinning

Electrospinning has recently emerged as a technique due to the possibility of fabricating nanofibers.  Electrospraying apparatus consisted of a syringe pump, syringe, needle tip, high voltage power supply, earth grounding, and an air gap having collector plate wrapped with aluminum foil. In this study, we address the influence of the shape and size of air gap in a collector plate on fiber density, fiber configuration, and pore size of fibers using synthetic and natural polymers.  

SEM morphology showed that the shape of air gap affects the pattern of fibers.  For the circular gap in the collector plate, the fibers were randomly deposited throughout the entire void of the collector plate.  For the triangular gap, the fibers aligned perpendicular to the bisector of the vertices at the edge of the vertices.  For the rectangular void, the fibers aligned from one short side to the other side perpendicular to the long sides of the rectangle in large scale.  Quantification study revealed that when the size of air gap was increased from 0.9 cm via 1.4 cm to 1.9 cm, the average pore size of fibers increased from 14.71, 22.83, and 57.77 μm since fiber density on air gap decreased when the gap size increased.

Simulation study using electrostatics module of COMSOL with passion equation revealed that the equi-potential surface collapses into the air gap. Since the dragging force generated by the electric field will be perpendicular to the equi-potential surfaces and the polymer fiber with be directed along the steepest potential decent direction, that is, to take the shorter path with respect to its initial launching direction and accumulate at the aluminum surfaces. Otherwise, fiber density is low at air gap due to the collapsed equi-potential surface. Also, the strong electric forces at the aluminum gap edges will stretch the polymer fiber and form aligned fiber at the edge of triangular gap.