Theory of polydispersity effects on polymer rheology. Binary distribution of molecular weights.

The flow properties of polymer systems are largely controlled by the process of molecular disentanglement. Polydispersity of the molecular weights of the macromolecules is expected to have a large effect. The entanglements may be considered as effectively forming a tube around each module. The molecule can escape from the tube, relaxing whatever constraints the tube imposes, by reptation (back and forth Brownian motion along the tube).