AbstractCommercial samples of cis‐1,4‐polybutadiene and trans‐1,4‐polybutadiene have been chlorinated with chlorine gas in a chloroform solution and precipitated with methanol. The precipitates were thoroughly washed with a large amount of methanol and dried in vacuum at 40°C. The samples were fractionated with the tetrahydrofuran‐water system at 40°C. The viscosity measurements were made at 30°C. in various solvents. The light‐scattering measurements were made with a modified Brice‐type light‐scattering photometer with unpolarized blue light and with a cylindrical cell, over the angular range from 35° to 145°, at room temperature. The relation between the intrinsic viscosity and the molecular weight was obtained for each sample. The unperturbed mean‐square end‐to‐end distance was estimated by the Stockmayer‐Fixman equation, and was used for calculating the conformational parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \sigma = \;(\overline {r_0 ^2 } /\overline {r_{0f} ^2 })^{1/2} $\end{document} for each chlorinated sample. The relation between the chemical configuration and the chain conformation for each chlorinated sample was discussed in terms of the unperturbed molecular dimension and rotational isomers of model compounds for a rotation around the CC bonds in the main chain.
