From capillary to elastic instability of jets of polymeric liquids: Role of the entanglement network of macromolecules

By example of a series of polymers with molecular masses in a wide range, it has been shown that mechanisms of the instability of jets formed by diluted and moderately concentrated polymer solutions are different. A change from the capillary mechanism of breakup of a jet to the phase-separation instability inherent in polymer solutions occurs above the critical value of the dimensionless parameter — the product of the concentration and the intrinsic viscosity. This transition is determined by the conditions of the appearance of the entanglement network, which is also responsible for the possibility of large strains at the extension of a solution. The stability of a jet is achieved only at quite high strain rates at which a transition from the liquid solution to a rubbery-like oriented jet separated from the solution occurs.