Relation of intrinsic viscosity of polymer solutions to degree of polymerization and temperature

The fundamental basis of our work is the application of statistics involving both the energy of interaction between solute and solvent molecules and the effect of steric hindrances: the statistics of freely rotating chains (sometimes called the statistics of Kuhn) are a special limiting case. Using this we can show that in the law [η] = KNα the coefficient is a function of N having a value close to 2 for small values of N, and approaching on first approximation a value of 0.5 when N increases infinitely. This statistical method has the advantage of permitting an approach to the important problem of the variation of the intrinsic viscosity as a function of the temperature T. The behavior of intrinsic viscosity with degree of polymerization and temperature as predicted by the theory check with experiment, and, in the case of the hemipolystyrenes, it has been possible to obtain very satisfactory quantitative verification. In view of numerous experiments which show that, at a given temperature, the limiting value of α for very large N is greater than 0.5, we have altered the theory of the equivalent particle accordingly. As a basis for the change the concept of porosity is examined with several other concepts, and it is shown that it is likely to apply only with reservations when the molecular structure of the solvent is taken into account.