DIELECTRIC-RELAXATION OF AMORPHOUS POLY(PROPYLENE OXIDE)S AT GIGAHERTZ FREQUENCIES

Dielectric relaxation properties of amorphous poly(propylene oxide)s w ith nominal molecular weights of 1000 and 2000 have been studied as a function of temperature at gigahertz frequencies using a time-domain r eflectometry method. Two relaxation processes were observed in the die lectric spectra. The dielectric relaxation parameters were quantitativ ely estimated by the Havriliak-Negami equation. At the lower frequency side of the main dispersion, a normal-mode relaxation was seen and th e relaxation times obtained from the spectra were found to be approxim ately one decade longer than the values calculated assuming the Rouse- Zimm theory. The hydrogen-bonded structures in the system are discusse d. The relaxation strength is also discussed in terms of chain conform ation. The relaxation times of the higher frequency process were found to be independent of the molecular weight. The shortest possible rela xation times estimated by the Vogel-Fucher-Tamman equation were in goo d agreement with those reported before.