Homogeneity of Needleless Electrospun Nanofiber Mats

Abstract

Nanofiber mats can be electrospun by different techniques, usually subdivided into needle-based and needleless. The latter allow for producing large-area nanofiber mats, e.g., with a width of 50 cm and lengths of several meters, if electrospinning proceeds for several hours, depending on the required thickness. Even spinning smaller samples, however, raises the question of homogeneity, especially if defined mechanical properties or a defined thickness is required, e.g., for filtration purposes. Very often, only the inner parts of such electrospun nanofiber mats are used to avoid too high variation of the nanofiber mat thickness. For this study, we used wire-based electrospinning to prepare nanofiber mats with slightly varying spinning parameters. We report investigations of the thickness and mass per unit area, measured on different positions of needleless electrospun nanofiber mats. Martindale abrasion tests on different positions are added as a measure of the mechanical properties. All nanofiber mats show unexpectedly strong variations of thickness, mass per unit area, and porosity, as calculated from the apparent density of the membranes. The thickness especially varied by nearly one order of magnitude within one sample, while the apparent density, as the most uniform parameter, still showed variations by more than a factor of two within one sample. This shows that even for apparently highly homogeneous areas of such nanofiber mats, variations cannot be neglected for all potential applications.

Suitability of Mycelium-Reinforced Nanofiber Mats for Filtration of Different Dyes

“…The mass of each specimen was measured by an analytical balance VWR LA Classic (VWR International GmbH, Darmstadt, Germany). Even in the case of optically homogeneous nanofiber mats, a study has shown strong deviations in areal weight and thickness between neighboring segments [33], making it necessary to measure each single sample. To investigate the influence of the areal weight, thicker and thinner areas of the produced nanofiber mats were chosen, resulting in a broad range of areal weights of about 0.9 g/m 2 -13.9 g/m 2 .…”

Electrospinning of Magnetite–Polyacrylonitrile Composites for the Production of Oxygen Reduction Reaction Catalysts

“…The components of needle-free electrospinning are an upper wire, a lower wire, a carriage containing a polymer solution and a substrate for collecting the nanofibers, which are generated in a high-voltage field. The lower wire is coated with an electrospinning solution, Taylor cones are formed in the electrospinning process, and the resulting nanofibers are deposited onto a nonwoven substrate, such as polypropylene, located under the upper wire [14]. The needle-based electrospinning machine, on the other hand, consists of a pump, a syringe, a high-voltage power supply, a needle and a collector.…”