The viscosities of concentrated polymer solutions. I. Moderately concentrated solutions

The enormous increases of the viscosity, η, and the associated activation heat, Qη, in concentrated polymer solutions are attributed to the formation of intermolecular linkages between high polymer molecules and to the increase of glass transition temperature with increasing concentration of the solution. In this paper, the effects of the intermolecular linkages on the viscosity of moderately concentrated solutions were discussed. In this concentration range, η and Qη are represented by unique functions of reduced concentration, vR = BMv2, and the following equation was derived for Qη; Here M is the molecular weight of the polymer, v2 is the volume fraction of the polymer, ΔE is the energy to form an intermolecular linkage, B is a constant for the solution, and Qη0 is the activation heat of viscosity for the solvent. The dependency of η on vR shifts from a first power proportionality to a third power at vR = 1/2. The theory was compared with experiments for solutions of cellulose tributyrate in trichloropropane, polyvinyl alcohol in water, polyvinyl acetate in acetone, and polyisobutylene in xylene.