New View of Entanglements in Dense Polymer Systems

A preaveraged topological parameter, $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{N}$, is introduced to provide a criterion for the presence of entanglements in polymer melts. The theory predicts a geometrical transition from the entangled to the unentangled state in agreement with experimental data. A generalized Rouse theory is used to describe polymer dynamics in both states.