Entangled linear polymer chains in melts: n.m.r. and Rouse or reptation models; stress relaxation

This study deals with detailed descriptions proposed to analyse slow chain diffusional process effects on n.m.r. properties of nuclei linked to long linear polymer molecules in melts or in concentrated solutions. It aims to predict relationships among macroscopic viscoelastic properties and semi-local dynamical properties observed from n.m.r. These relationships are discussed considering two main models of low-frequency chain fluctuations in melts: a multiple relaxation-mode spectrum analogous to a Rouse model or a single relaxation-mode spectrum analogous to a reptation model. The two descriptions are compared with each other. The Rouse model was chosen because n.m.r. properties might be sensitive to the equilibration process of conformational fluctuations within a so-called ‘tube’ as well as to the reptation in a ‘tube’. Also, the Rouse model is more easily handled than the reptation one. Local molecular properties are transferred to the unusual n.m.r. semi-local space scale (