Effects of hampered draining of solvent on the translatory and rotatory motion of statistically coiled long‐chain molecules in solution. Part II. Rotatory motion, viscosity, and flow birefringence

Abstract

In Part I the translational resistance of the random coil was discussed. In the two limiting cases of the freely draining and the completely nondraining coil a theoretical treatment was given, while for intermediate draining conditions an experimental method, involving large‐scale models of the molecules, was shown to be available. The same treatment is now extended to deal with the analogous case of the hydrodynamic rotational resistance of the random coil. It is on this characteristic resistance that the intrinsic viscosity and the flow birefringence of solutions of chain molecules principally depend. magnified image Expressions are found for the viscosity index [η], the orientation index [ω], and the birefringence index [n], respectively. In these formulas Z is the degree of polymerization while the parameters a_η, a_η, a_η, and b_rot are independent of Z. These parameters are, however, functions of the length A_m of the preferential statistical chain element and the hydrodynamic thickness d_h of the chain. a_n also includes the anisotropy of polarizability of the statistical chain element. It is seen moreover that [ω] (in contrast to [η] and [η]) also depends on the shape resistance of the chain (i.e., on the resistance which the chain inherently offers to a rapid change in configuration).