CONFORMATION AND PHONON-DISPERSION IN TRANS-1,4-POLYBUTADIENE

Phonon dispersion studies for trans-1,4-polybutadiene (TPBD) are repor ted. The change in profile of the dispersion curves as a function of t he =CH-CH2-dihedral angle phi has been obtained in order to find the g eometry of the polymer that gives the best interpretation of the spect ra. It is found for phi = 71 degrees. The regions of high density of s tates obtained from the dispersion curves for an isolated chain have b een used to explain the features of the spectra. Some of these, which were earlier attributed to interchain interactions, in fact arise due to intrachain interactions. Prominent features of the dispersion curve s are discussed and heat capacity, derived therefrom, is reported. Cal culations have also been performed for unsaturated C-deuterated and fu lly deuterated TPBD samples to check the validity of the force field a nd assignments.