Coil-Uncoiled Chain Transition of Polyethylene Oxide Solutions under Convergent Flow

The coil-uncoiled chain transition under convergent flow of polyethylene oxide aqueous solutions has been studied. The possibility of this transition has been confirmed by the experiments. The fields of velocities and their gradients arising at the entrance of a small capillary during the convergent flow have been examined. It was found that water-polyethylene oxide system under convergent flow and certain flow regimes is self-regulating one with a negative feedback. The latter manifests itself in the following: accelerated longitudinal gradients of velocity lead to deformation of macromolecular coils, followed by a rearrangement of the flow in such a way as to increase the impact time of the longitudinal velocity gradient on macromolecules. The hydrodynamic field arising under the convergent flow provides a considerable degree of polymer uncoiling and coil-uncoil chain transition.