| Abstract: | Direct current (dc) and alternating current (ac) electrical properties of semicrystalline poly(butylene terephthalate) (PBT) are investigated as a function of temperature and frequency. Dc electrical conductivity measurements have been performed over the temperature range ?75°C to 130°C and point out an essentially ionic mechanism of charge transport. Charge carriers are identified in protons supplied by ionization of carboxyl end-groups after dissociation of the existing hydrogen bonds. Dielectric constant and loss factor have been measured over the temperature range ?100°C to 130°C and over the frequency range 10?6 to 106 Hz. Together with de measurements, they allow the detection of the α glass-rubber and the β subglass relaxation processes, as well as an interfacial polarization of the Maxwell–Wagner–Sillars type. Finally, the contour map of loss factor, summarizing the overall dielectric behavior of the polymer, is reported and discussed for electrical applications of PBT. |
