Eduard Zhmayev

Electrohydrodynamic quenching in polymer melt electrospinning

Infrared thermal measurements on polymer melt jets in electrospinning have revealed rapid quenching by ambient air, an order of magnitude faster than predicted by the classical Kase and Matsuo correlation. This drastic heat transfer enhancement can be linked to electrohydrodynamic (EHD) effects. Analysis of EHD-driven air flow was performed and included into a comprehensive model for polymer melt electrospinning. The analysis was validated by excellent agreement of both predicted jet radius and temperature profiles with experimental results for electrospinning of Nylon-6 (N6), polypropylene (PP), and polylactic acid (PLA) melts. Based on this analysis, several methods that can be used to inhibit or enhance the quenching are described.

Modeling of Crystallizing Polymer Melts in Electrospinning

In electrospinning, applied electric field elongates a charged fluid jet to produce nanofibers. While most polymer melts result in highly‐aligned amorphous structures, some fast‐crystallizing polymers such as Nylon can produce semi‐crystalline fibers, and by controlling this crystallinity the mechanical properties of electrospun fibers can be tailored. Short inflight residence times, high extensional forces, and radially‐uniform stress distributions in electrospinning result in the dominance of flow induced crystallization (FIC) and a nearly 1D microstructure. We present our FIC model based on Kolmogoroffs equation, Hoffman‐Lauritzen theory, and key modifications from molecular scale insights to account for flow effects. The model behavior is compared to the conventional Ziabicki FIC model using Nylon‐6,6 as the model polymer.