The process of charging a polymer solution to draw a filament is known as electrospinning. Electrospinning is capable of producing a continuously depositing jet of controllable micron and sub-micron diameters. As fiber deposits, a nonwoven mat of randomly oriented fibers in two dimensions is generated. The mat is mechanically robust and suitable for a wide variety of applications due to its high surface area to mass ratio, controllable size scale and surface chemistry, and large void fraction. The number of publications on the topic of electrospinning continues to grow exponentially, as the experimental apparatus is relatively inexpensive to assemble and 1 mm thick fiber mats can be generated in as little as 2 hours. Many publications have focused on potential applications or the processing of specific materials. Some publications have reported on the hydrodynamics and physics of the electrospinning process, leading to an increased control of fiber diameter and morphology. One area that remains relatively unexplored is pore diameter and porosity within the fiber mat. The present work explores characterizing and controlling void space in electrospun materials and the use of these materials in the field of tissue engineering. Characterization and prediction of overall void fraction and individual pore diameter is first addressed. Mercury porosimetry was used to establish two physical parameters useful in electrospinning applications: average pore diameter and peak pore diameter. Average pore diameter refers to the volume-weighted average determined by the volumetric profile. Peak pore diameter is the pore diameter at which the largest amount of void volume becomes accessible.
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