Viscoelastic Properties of Polystyrene Solutions

Abstract

Quartz crystals resonant in the fundamental torsional mode at frequencies of 40 and 73 kc/sec have been used to measure the viscoelastic properties of solutions of polystyrene in toluene, methylethylketone, and cyclohexane. A monodisperse polystyrene sample of molecular weight 2.39×105 was employed. The results have been compared with those of Harrison, Lamb, and Matheson (1964) for dilute solutions in toluene of a number of polystyrene samples of different molecular weight. In toluene, it is found that 25% of the contribution of the polymer to the viscosity of the solution is not able to take part in viscoelastic relaxation, and that the dynamic viscosity at high frequencies (the “Einstein viscosity”) is greater than the solvent viscosity. Under these conditions, the viscoelastic behavior of all time solutions of toluene of polystyrene samples of different molecular weights agrees with the predictions of the Rouse theory. From time value obtained for the Einstein viscosity of the solutions, it is shown that the radius of time equivalent hydrodynamic sphere is approximately proportional to the square root of the molecular weight of the polymer molecule. The viscoelastic behavior of the solution in methylethylketone is intermediate between the predictions of the Zimm and Rouse theories.