Vibrational dynamics and heat capacity in syndiotactic poly(propylene) form I

Normal modes of vibration of syndiotactic polypropylene (sPP) and their dispersion are obtained in the reduced zone scheme for helical form I having the conformational sequence (t2g2) using Urey-Bradley force field and Wilson's GF matrix method as modified by Higgs. Optically active frequencies corresponding to the zone center and zone boundary are assigned and characteristic features of the dispersion curves are discussed. In general the dispersion in the helical form is less as compared to the planar form. Heat capacity has been calculated via density-of-states using Debye relation in the temperature range 10-460 K and compared with the experimental measurements.