Dielectric relaxation in concentrated solutions of cis-polyisoprene. Part 3.—Relationship between friction coefficient for dielectric normal-mode process and local segmental motions

Abstract

The data of dielectric normal mode process (αI) and the segmental mode process (αII) reported in parts 1 and 2 of this series were analysed to find a relationship between the friction coefficient ζ for the normal mode process and the relaxation time τs for the segmental mode process. Assuming τs proportional to ζ, we attempted to superpose the τnvs. molecular weight Mw plots for solutions with different concentrations C. From the vertical and horizontal shift factors, we found that the monomeric friction coefficient ζm is approximately proportional to C2τs. To explain this result, we assumed that the effective size for the segmental motions expands with decreasing C. The molecular weight M0 for the unit of the segmental motion was estimated based on the computer simulation reported by Verdier and Stockmayer. The M0 was found to be 77 for bulk cis-PI and increased with decreasing C approximately in proportion to C–1.