Intrinsic Viscosity of Polymer Chains

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Abstract
The intrinsic viscosity [η] of polymer chains is recalculated by methods similar to those of Kirkwood and Zimm. The theory is based on the preceding paper by Fixman, with the adoption of a smoothed excluded‐volume potential and the following first‐order approximation to the operator L which determines the segment coordinate distribution function ψ; for L acting on the nonequilibrium part of ψ, only the diagonal part of L in the free‐draining basis representation is used. This corresponds qualitatively to the Zimm theory in Hearst's version. However, the avoidance of preaveraging the Oseen hydrodynamic interaction tensor in the present work leads to larger values for the relaxation times of various normal modes when the hydrodynamic shielding effect is not negligible. The effect is more pronounced for lower modes, amounting to about eight percent increase in the lowest mode excited by the velocity gradient in the nondraining limit. The value of [η] in the same limit is found to be [η]=2.68×1023 L3/Mw (L: the root‐mean‐square end‐to‐end distance, Mw: the molecular weight of the polymer; cgs units) and is about 5% lower than that obtained by the Zimm treatment. A similar correction to the flow birefringence extinction angle is also given.