ABSTRACT
The former chapters of this book have shown that electrospun nanofibers have diverse applications in both textile and nontextile areas. Rotating coil may form a highly efficient needleless electrospinning system for mass production of nanofibers. In comparison to other rotating fiber generators, coil spinneret has much stronger and more concentrated electric field intensity in the fiber generating area. This is the main reason as to why coil electrospinning has higher fiber productivity with a much better control toward the fiber quality when compared with existing needleless electrospinning systems. A coil system with multiple rows of long coil spinnerets can produce continuous nanofiber mats of sufficient thickness and width in a single process. A coil electrospinning system can be used as a standalone machine for nanofiber production or incorporated into an existing production line to produce nanofiber-functionalized nonwovens, filter papers, and other fibrous products. Our studies have shown that the finite element method can be used to understand the electrical field profiles in electrospinning, which are difficult to measure directly in a high electric field environment. By combining the finite element analysis with experimental results, the coil electrospinning can be further optimized and new electrospinning systems may be designed also. Much work on electrospinning has been focused on the fiber generators, rather than the fiber collectors. The fiber collectors play
a critical role in determining the final nanofibrous structures. More works need to be done on fiber deposition to effectively control the fiber orientation in the fibrous structure. It is also a challenge to electrospin nanofibers into yarns, an important building block to construct intricate fibrous structures other than the simple nonwovens. This would also require accurate control of the number of nanofibers from a needleless electrospinning system. At present, the exact number of fibers generated in a needleless electrospinning process is unknown. In summary, needleless electrospinning represents an important technology for mass production of nanofibers. This technology will greatly facilitate the applications of nanofibers in different areas. Further work is still required to precisely control the fiber properties and the nanofibrous structures in needleless electrospinning. In addition, new needleless electrospinning systems and novel fiber collectors should be designed to produce nanofiber yarns, which will further expand the applications of nanofiber materials.
