Influence of controlled ionic conductivity on melt electrospinning of polyethylene*

The ionic conductivity of thermoplastic melts was increased by incorporating commercial additives which altered the characteristic size scales in the electrospinning process, resulting in an order of magnitude decrease in fiber diameter and formation of some fibers as small as 200-300 nm. By utilizing an unconfined geometry (a fluid-covered flat plate), where the melt spontaneously forms and organizes many fiber-generating cone-jets, changes in the wetting properties under the applied electric field can be observed. These changes can be described by simple models and confirm results from independent fluid property measurements. We discuss results from two commercial formulations of linear low-density polyethylene as a function of additive concentration and correlate changes in fluid properties with the time to first fluid perturbation, the number of jets, the capillary length (due to the electric force), the cone and jet sizes and the resulting fiber diameter. The development of high strength mesoscale thermoplastic nanofibers could have significant importance for filtration and biological applications.