Chemical Engineering Science, Vol.56, No.19, 5555-5564, 2001
The influence of the range of excluded volume interactions on the linear viscoelastic properties of dilute polymer solutions
The Rouse model has recently been modified to take into account the excluded volume interactions that exist between various parts of a polymer chain by incorporating a narrow Gaussian repulsive potential between pairs of beads on the Rouse chain (Prakash, Macro molecules. 2001. 34, 3396-3411). The narrow Gaussian potential is characterized by two parameters: z*-which accounts for the strength of the interaction, and d*-which accounts for the range of the interaction. In the limit of d* going to zero., the narrow Gaussian potential tends to the more commonly used delta -function repulsive potential. The influence of the parameter d*. in the limit of infinite chain length, on equilibrium and linear viscoelastic properties, and on universal ratios involving these properties, is examined here. A renormalization group calculation of the end-to-end vector Suggests that the Value chosen for the variable d* will not affect critical exponents, or universal ratios. A similar trend is also observed for results obtained with all approximate solution, which is based on the assumption that the non-equilibrium configurational distribution function is Gaussian.
Keywords:rheology;polymer;solutions;modeling;viscoelasticity;good solvent;excluded volume;universal behavior