DISPERSION CURVES AND FREQUENCY DISTRIBUTIONS OF ISOTACTIC POLYPROPYLENE

Dispersion curves and a frequency distribution were calculated for isotactic polypropylene on the basis of a single-chain model using a valence force field previously reported in the literature. The obtained results provide useful information for the interpretation of the inelastic neutron scattering spectrum published by other authors. It is shown that calculations on the single-chain model account for practically all peaks in the experimentally determined frequency distribution. Most of these peaks arise from phase values which do not correspond to spectroscopically active motions.