DIELECTRIC-SPECTROSCOPY ON CIEJ/WATER MIXTURES AS A FUNCTION OF COMPOSITION

At 25-degrees-C the complex dielectric permittivity of mixtures of water with low-weight poly (ethylene glycol) monoalkyl ethers (C(i)E(j)) has been measured as a function of frequency nu (1 MHz less-than-or-equal-to v less-than-or-equal-to 55 GHz) and mole fraction x(0 less-than-or-equal-to less-than-or-equal-to 1). Various relaxation spectral functions are fitted to the measured spectra. It is found that the dielectric relaxation of all liquids (i,j = 2,2; 4,2; 6,2; 4,3; 4,1) can be consistently described by a sum of a Debye term with discrete relaxation time and a Davidson-Cole term with an underlying unsymmetrical relaxation time distribution. With the exception of the C4E3/H2O mixtures the Debye term vanishes at high content of C(i)E(j) molecules (x>0.25). It is assumed that this term represents a water-rich subphase while the Davidson-Cole term reflects a microphase of low water content. With the C4H3/H2O system crankshaft-like motions of the C4E3 molecule obviously also contribute to the Debye term which exists also in the spectrum of the pure organic liquid. The parameters of all spectra are discussed with respect to the composition of the microphase of low water content, to effects of dipole orientation correlation, and to the mechanism of dielectric relaxation in associated liquids.