SOME REMARKS ON THE DYNAMICS OF POLYMER MELTS

This paper presents theoretical considerations of dynamic conformations of a single chain of N monomeric units immersed in a monodisperse melt of the same chemical composition, but with a different polymerization index P. The authors propose some tentative scaling laws for the self-diffusion constant D(N) and the relaxation time T(N) of the solute chain. They also discuss the viscosity increment delta eta due to a small volume fraction PHI of the long chains. They find three regimes of behavior, depending on N and P, and on the distance between entanglement points (assumed smaller than N and P): (A) reptation of the N chain; (B) Stokes-Einstein regime; the solute moves like a usual polymer coil in a viscous fluid of P chains; (C) mixed regime, where D(N) is controlled by reptation, while delta eta is of type B. It is concluded that there is no significant regime where the process of ″tube renewal″ could be dominant.