ABSTRACT. Using time domain reflectometry, the complex dielectric spectra between 10 MHz to 20 GHz has been measured in the whole composition range at 10, 20, 30 and 40 o C for the binary mixtures of ethylene glycol and dimethyl sulfoxide. For all the mixtures, only one dielectric loss peak was observed in this frequency range. The relaxation in these mixtures can be described by a single relaxation time using the Debye model. A systematic variation is observed in dielectric constant (ε0) and relaxation time (τ). The excess permittivity (ε E ), excess inverse relaxation time (1/τ) E , Kirkwood correlation factor (g) and thermodynamic parameters viz. enthalpy of activation (∆H) and Gibbs free energy of activation (∆G) have been determined, to confirm the formation of hydrogen bonded homogeneous and heterogeneous cooperative domains, the dynamics of solute -solute interaction and the hindrance to molecular rotation in the hydrogen bonded glass forming ethylene glycol -dimethyl sulphoxide system.
Time domain spectroscopy in reflection mode has been used to determine complex reflection coefficient for 2-ethoxyethanol-dimethyl sulfoxide (DMSO), ethanol-DMSO, and propan-1-ol-DMSO mixtures at 293, 303, 313, and 323 K, in the frequency range of 10 MHz to 10 GHz. Further Fourier transform and least-squares fit methods have been used to obtain the complex permittivity, static dielectric constant, and relaxation time.
Using picosecond Time Domain Reflectometry (TDR), dielectric relaxation studies have been carried out on binary mixtures of methyl methacrylate with 1-propanol, 1-butanol, 1-heptanol and 1-octanol for various concentrations over the frequency range from 10 MHz to 10 GHz at 293 K. The Kirkwood correlation factor and excess inverse relaxation times were determined and discussed to yield information on the molecular structure and dynamics of the mixture. The static permittivity and relaxation time decrease with an increase in the percentage of methyl methacrylate.
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