THE EFFECT OF TEMPERATURE AND MIXED-SOLVENT COMPOSITION ON THE INTRINSIC VISCOSITY OF GR–S

The intrinsic viscosity of a sample of GR–S has been measured, at temperatures ranging from 0° to 65 °C., in several solvents made progressively 'poorer' (to the point of precipitation) by the addition of nonsolvent. The results afford strong evidence in support of the theory (Flory; Alfrey, Bartovics, and Mark) that intrinsic viscosity is very sensitive to the shape assumed by a flexible long-chain molecule in solution and that this shape varies with the nature of the solvent and with the temperature. Measurements with various systems of the type GR–S–solvent–nonsolvent indicate that the intrinsic viscosity at the precipitation point is the same with different nonsolvents and, to a first approximation, with different solvents. This intrinsic viscosity is, moreover, independent of temperature.