A certain “critical” molecular weight controls rheological properties of the multibead finitely extensible nonlinear elastic (FENE) chain model polymer melt. The rheological crossover manifests itself in a change of power law behavior for the viscous properties at a critical number of beads per chain $N_c=100\mathrm{}\pm 10$. This finding confirms a newly proposed relationship between dimensionless critical weight, characteristic length, and flexibility which we obtain as a side result. Results further suggest that the entanglement molecular weight $N_e$ for the flexible FENE chain model could be comparable in size or even larger than its critical molecular weight $N_c$.

• Received 16 December 1999

DOI:https://doi.org/10.1103/PhysRevLett.85.1128