Development of Melt Spun Polymer Nanofibers

Melt spinning is an inexpensive means of producing highly oriented and crystalline fibers. Industrial production rates are typically 1000s of meters per minute. Creating “good quality” fibers becomes increasingly difficult as the diameter of the fibers is decreased to below approximately 10-15 microns. One approach to making very small fibers is to use High Island Count Islands-in-the Sea (HICINS) technology. In this approach, smaller streams of polymer called the “islands” are incorporated into a larger stream of polymer called the “sea” or confining polymer, which is then spun into a fiber. The resulting fiber can then be drawn to produce very small fibers or nanofibers (island polymer). Bi-component fiber trials were conducted to produce nanofibers having a diameter of 100 nm or less. Trials using polypropylene as the nanofibers (islands) with poly(lactic acid) or polyethylene as the confining polymer (sea) were fabricated. The nanofiber confinement diameter was controlled by varying the number and volume fraction of the islands as well as processing conditions. We will discuss the methodology for reaching 100 nm diameter fibers and the characterization of those fibers.