Rheological behavior of dilute polymer solutions in a general velocity field

Abstract

Abstract The rheological equation of state (constitutive equation) and the average rate of dissipation of energy flow are calculated for dilute solutions of flexible chain macromolecules. It is shown that such solutions may be considered as nonlinear viscoelastic fluids, the parameters of the equation of state being determined by the structural characteristics of the system: relaxation times τ i and internal viscosity ρ i . It is shown that in a general case the stress tensor is asymmetric; the antisymmetric part vanishes for systems with zero internal viscosity (ideally flexible chains). On the basis of structural data it is shown that the rheological equation of state may be linearized when the stress tensor is referred to the actual structure of the system. For the general case ( ρ i > 0, chains with limited flexibility) the average rate of dissipation of energy in the flowing system depends on the asymmetric part of the stress tensor as well as on the symmetric part.