DYNAMICS OF A POLYMER DILUENT SYSTEM AS STUDIED BY DIELECTRIC-SPECTROSCOPY AND NEUTRON-SCATTERING

Dielectric spectroscopy and incoherent neutron scattering are employed to study the dynamics of concentrated solutions of solution-chlorinated polyethylene with bis(2-ethylhexyl)phthalate. The dielectric measurements were made at temperatures (T) between 200 and 435 K and in the frequency range from 10(-1) to 10(9) Hz. The incoherent neutron scattering measurements covered the T range between 4 and 400 K and the Q range from 0.33 to 1.84 angstrom-1. From dielectric spectroscopy (DS) we obtain the T dependence (i) of the dynamics and (ii) of the distribution of relaxation times over a broad frequency/temperature range. Our results for the dynamics are discussed in terms of the Vogel-Fulcher-Tammann (VFT) approach with a single primary (alpha) relaxation affecting the DS data. Our results for the distribution of relaxation times, obtained either in the frequency domain or in the time domain, display a systematic T dependence with significantly broader distributions for the mixtures, at low T, as compared to the bulk polymer and the neat solvent. This is discussed in terms of theoretical models which predict a narrowing of the distribution with increasing T. From the neutron scattering experiment, made on the same samples but at a higher frequency range, we obtained evidence for enhanced proton mobility with T, setting in at about the characteristic temperature (T0) of the VFT approach.