Microscopic and macroscopic evaluation of fundamental facets of the entanglement concept.

We present a study on the temperature dependence of the microscopic entanglement distance, the chain dimension, and the plateau modulus of poly(ethylene propylene) alternating copolymer. The results provide insight into the microscopic origin of entanglement constraints and favor packing and scaling models over the topological approach. Furthermore, these results are at variance with one of the basic relations of the Doi-Edwards theory of viscoelasticity which unites the elastic response of a polymer melt with the entanglement distance.