- Description of the effort: This effort is carried out on two fronts. On one front, it utilizes an integrated experimental and modeling approach to perform a fundamental study on environmental effects in production of nanofibers via multi-needle electrospinning. In this regard, we have considered the effect of solvent vapor and humidity on morphology of fibers and mats of fibers in solution based electrospinning. On the other front, it is focused on major innovations in melt-electrospinning and coupling energy to matter to develop thermoplastic nanofibers.
Figure: Left: (a) Schematic of and (b) a photo of the actual multi-needle electrospinning setup with a stationary collector – Aluminum foil. (c) Reservoir with metallic miniature needles. Right: Pile up phenomena in electrospun nanofibers observed in certain humidity ranges.
Figure: Left: Schematic of Electrospinning setup with downstream radiation-based heating, Right: Initial Profile (a) comparison between experiment and simulation (b) CCD image of the as electrospinning jet.
- Main findings so far:
- We have realized that the minimum natural flow rate per needle is highly dependent on needle-to-needle spacing. We explained the observed trend by considering the partial pressure of solvent vapor peculiar to multi-needle setup and the stress relaxation in the electrospinning solution jet.
- We alluded to the critical role of humidity in production of nanofibers via multi-needle electrospinning. We demonstrated that increasing the humidity beyond a threshold (a function of the distance between needles) can lead to sudden change in the morphology of the electrospun fiber mats, with significant effects on fiber diameter.
- In case of melt electrospinning, we utilized a model for non-isothermal melt electrospinning in the presence of a volumetric heat source. Our simulation results demonstrate that downstream heating does reduce the fiber diameter, and is therefore a feasible approach for resolving the limitations of melt electrospinning. In addition, our model has also been used to capture the effect of the surrounding temperature, which affects the thinning of the fiber through surface rather than volumetric interactions. Finally, melt electrospinning experiments are utilized to validate the model predictions for downstream heating.
- Funded by NSF and QNRF
- Senior personnel involved: Drs. Naraghi, Green and Creasy (PI is Dr. Naraghi- NSF), Drs. Palazzolo, Naraghi, Creasy and Tafreshi (PI is Dr. Palazzolo- QNRF)
- Mayadeo N., Morikawa K., Naraghi M., and Green M., “Modeling of downstream heating in melt electrospinning of polymers”, Journal of Polymer Physics Part B: Polymer Physics, in press, 2017.