ABSTRACT
Rapid solvent evaporation first leads to the formation of a solid skin, followed by further evaporation from the liquid core, leaving voids previously occupied by solvents and allowing partial relaxation of the matrix. Skin formation prevents further stretching and orientation of polymer chains within the semi-liquid fiber core. In order to identify the required mechanism allowing to fabricate homogeneous fibers, the evolution of the polymer system within the semi-dilute solution jet during electrospinning should be analyzed. Spinnable polymer solutions are semi- dilute, highly entangled. This chapter demonstrates the solvent wringing out of a fiber and the formation of a near-surface layer of the solvent around an oriented polymer filament. It highlights that the necessary slipping and disentanglement of macromolecules are possible only if the difference in hydrodynamic forces applied to the ends of a macromolecule is larger than a critical value.
