Influence of salt additives on unconfined melt electrospinning of thermoplastics

Incorporation of ionic or salt additives into thermoplastic melts can effect both viscoelastic properties and ionic conductivity. Such an approach might usefully alter the process of melt electrospinning where jet diameter (and subsequent fiber size) is influenced by melt viscosity as well as ionic motion within the melt under the influence of a strong applied electric field. These changes have the potential of producing mesoscale thermoplastic nanofibers which are important for filtration and biological applications where high strength nanofibrous materials are required. We report ionic conductivity measurements obtained using broad-band impedance spectroscopy of commercial linear low-density polyethylene (ASPUN 6850A) as a function of temperature, salt type, and concentration, along with corresponding information on viscosity changes. The salt-doped melts were electrospun in an unconfined geometry; changes in jet formation time, number of jets, jet and cone widths, and the resulting fiber diameters were determined. We discuss results and current understanding of the changes in melt properties due to salt additives.