Schnell, M. and Wolf, B. A.

"Viscosity of polymer/solvent systems: Quantitative description on the basis of molecular surfaces"

Journal of Rheology 2000, 44, 617-628.

Abstract: A model for the description of the viscosity of polymer/solvent systems made up of homologues, developed earlier, is generalized to normal polymer solvent mixtures. It is based on three premises: (i) the dissipation of energy takes place at the molecular interfaces, (ii) the friction between solvent and solute varies with composition due to a change in the flow mechanism (drainage of coils), and (iii) the specific hydrodynamic volume of the coils generally also depends on polymer concentration. The resulting simple expression contains four system-specific parameters: a geometric factor g, which accounts for the differences of the surface to volume ratios of the components; a viscometric interaction parameter a, which measures the friction between solute and solvent in the case of fully draining polymer coils, [h], the specific hydrodynamic volume of the polymer at infinite dilution (intrinsic viscosity), and [h]Q, the specific hydrodynamic volume in the pure melt. The suitability of this model is demonstrated by means of extensive experimental data reported in the literature for the systems diethyl phthalate/poly(vinyl acetate) and diethyl phthalate/poly(methyl acrylate). It appears worthwhile to mention that the evaluation yields [h] and [h]Q, even in absence of information within the relevant composition range, and that there exists a linear correlation between g and a.

preprint number: 207