Effect of Low Polymer upon the Intrinsic Viscosity of a High Polymer

Abstract

WHEN it is desired to express the results of solution viscosity measurements upon a high polymer as a molecular weight, the viscosity average molecular weight M is used. The concept is due to Flory¹. Its starting assumption is that, for the ith component of a polydisperse polymer sample, where (η_r − 1) is the relative viscosity increment due to the ith component, and C_i and M_i are its concentration and molecular weight. K and α are constants, assumed to be specific to the polymer/solvent system generally, and not to the particular component considered in equation (1). This contention would not be expected to be rigorously true, because the viscosity increment due to the ith component, which depends on its effective radius in dilute solution, would be affected not only by C_i and M_i, but also by the concentrations and molecular weights of all other species present. These other species, together with the solvent, will enter into the general interaction between polymer segments and solvent molecules upon which the final effective radius of the ith component will depend.