@article{sheoran_boland_thornton_bochinski_clarke_2023, title={Enhancing ionic conductivity in polymer melts results in smaller diameter electrospun fibers}, volume={123}, ISSN={["1077-3118"]}, url={https://doi.org/10.1063/5.0162384}, DOI={10.1063/5.0162384}, abstractNote={Chemically compatible additives were utilized to increase the ionic conductivity of polyethylene melts. When subjected to unconfined electrospinning, a predictable and significant decrease in the resultant fiber diameter with enhanced melt conductivity was observed. This generalized approach was confirmed for viscous melts, varying in conductivity over five orders of magnitude and viscosity 5×, from multiple commercial polyethylene formulations with various additives. These experimental results are connected to theory for the relevant length scales of capillary length, jet spacing, and jet radius. In particular, jet radius scales as conductivity to the −1/4 power. Fitting experimental fiber radius vs ionic conductivity data results in a similar power law exponent (−0.29). This trend, occurring at orders of magnitude higher viscosity and six orders of magnitude lower conductivity, is similar to results from needle-based, solution phase electrospinning, suggesting the generality of the effect. The connection between larger length scales, such as the distance between jets and the thickness of the film at the plate edge, and fluid properties (surface tension, viscosity, and conductivity) is also discussed.}, number={7}, journal={APPLIED PHYSICS LETTERS}, author={Sheoran, N. and Boland, B. and Thornton, S. and Bochinski, J. R. and Clarke, L. I.}, year={2023}, month={Aug} }
 @article{sheoran_boland_thornton_bochinski_clarke_2021, title={Increasing ionic conductivity within thermoplastics via commercial additives results in a dramatic decrease in fiber diameter from melt electrospinning}, volume={9}, ISSN={["1744-6848"]}, url={http://dx.doi.org/10.1039/d1sm01101d}, DOI={10.1039/d1sm01101d}, abstractNote={Polyethylene melt conductivity was increased by adding a commercial anti-static agent, which resulted in a 20× decrease in electrospun fiber diameter and formation of a significant fraction of sub-micron diameter fibers. Two polyethylene formulations and varying additive concentrations were utilized to span the parameter space of conductivity and viscosity. The key role of conductivity in determining the jet radius (which sets the upper limit on the fiber size) is discussed in the context of fluid mechanics theory and previous simulations. Parameters which affect the conversion of the liquid jet to a solid fiber and the pertinent theory are outlined. An "unconfined" experimental configuration is utilized to both avoid potential needle clogging and enable direct observation of important characteristic length scales related to the interaction of the fluid and the applied electric field. In this approach, the fluid spontaneously forms an array of cone perturbations which act as stationary "nozzles" through which the mobile fluid flows to form the jet. The experimental data and theory considerations allow for a holistic discussion of the interaction between flow rate, viscosity, conductivity, and the resultant jet and fiber size. Information about the fluid viscosity and conductivity gained by observing the electrospinning process is highlighted. Schemes for theoretically predicting the cone-jet density, cone size, and flow rate are compared to experimental results.}, journal={SOFT MATTER}, publisher={Royal Society of Chemistry (RSC)}, author={Sheoran, Neelam and Boland, Brent and Thornton, Samuel and Bochinski, Jason R. and Clarke, Laura I.}, year={2021}, month={Sep} }