DIELECTRIC-SPECTROSCOPY OF POLYSTYRENE POLY(ETHYLENE OXIDE) COMPOSITES/

Dielectric spectra of composites of poly(ethylene oxide), PEG, in poly styrene, PS, have been obtained, as a function of frequency and temper ature. The dispersion of a high-dielectric constant, low-glass transit ion temperature, semicrystalline polymer (PEG) in an amorphous, lower dielectric constant, high-T-g continuum (PS) has enabled the dielectri c observation of four molecular relaxation professes in PEG. They are the alpha relaxation associated with the crystalline melt of PEG; two WLF type relaxations, beta and beta', which we speculate to be respect ively associated with the onset of segmental motion and free-volume ex pansion of unrestricted amorphous PEO chains and with amorphous PEO ch ain segments tethered in crystallites; and a sub-T-g, gamma relaxation associated with localized motions in the crystalline chain segments. The relaxations associated with the alpha and beta' processes have not been previously observed dielectrically. In pure, neat PEG, the alpha and beta' relaxations are obscured by de losses. The dispersion of PE O as micron-sized and submicron phases in PS enables its full relaxati on spectrum to be observed.