Experimental Investigation of the Fiber Formation Process and Web Structures Using an Annular Meltblowing Spinneret

This research experimentally investigates the fiber and web formation process of an array of annular meltblown spinnerets. In this design, the molten polymer is extruded from an array of outlets, each of which is individually surrounded by a concentric high-velocity heated air stream. With its multirow capability, it potentially becomes a high-productivity microfiber fabrication process. We experimentally investigate the effects of critical processing parameters and material properties on the fiber and web formation process. First, the polymer thermal and rheological behavior is presented. Next, a detailed three-dimensional air temperature and velocity profile, measured in the absence of spinning fibers, is presented for an array of supplied temperatures and internal machine air pressures. Web analysis in relation to this air profile shows that smaller fibers in cooler air streams require shorter die-collector distances to form bonded fabrics. Calculations are then made that show polymer spinning temperature is largely determined by air temperature, a distinguishing feature of this meltblowing design. Finally, a full factorial variation of air temperature, air speed, and polymer throughput is shown that relates processing conditions to fiber diameter distribution. Median diameters are well described by an empirical model and ranged from less than 1 μm to almost 14 μm.