Change in the structure of a polymer solution in a longitudinal hydrodynamic field

There are two qualitatively different conditions for the stretching of liquid fibers formed by moderately concentrated polymer solutions [1]. If the longitudinal gradient of the drawing rate is rather small the structure of the solution remains unchanged. If this gradient exceeds a certain critical value, some of the solvent is expressed from the solution in and the liquid filament is converted into a slightly swollen fiber. The solvent released settles as droplets on the filament surface. This effect is of very great importance for a number of industrial processes pertaining to the production of filaments and films from polymer solutions. In addition, as was reported in [1], the drawing of a liquid filament, accomapnied by orientational formation of the solid phase, can serve as a most simple imitation of the formation of silk and gossamer filaments in nature.This paper presents a qualitative theory for this phenomenon, based on investigation of the thermodynamic stability of a polymer solution in a longitudinal hydrodynamic field.In conclusion the author thanks S. Ya. Frenkel for kindly providing information about the experiments conducted in his laboratory.