Dielectric Relaxation In Binary Glass Forming Mixtures Of Water And A Debye Liquid

An explicit picture of dynamics about the presence or absence of the Debyerelaxation in H-bonded liquids is still unaccessible, though the Debye relaxation hasalready been studied for decades, apperantly associating closely with thehydrogen-bonding (HB), however, water, as the most widespread substance on earth,whether such arrangements are present in water to arise the Debye relaxation remainsunknown. Crystallization is the main obstacle in the studying of water, and the dielectricrelaxation of aqueous mixtures with a Debye liquid is studied in the highly viscousregimes near the glass transition in order to get insight into the dynamics in water.N-ethylacetamide is chosen in view of the presence of the Debye-type relaxation,excellent glass forming ability and miscibility with water.The relaxation of mixtures of N-ethylacetamide (NEA) and water is studied in thehighly viscous regime near the glass transition with dielectric and enthalpy relaxationtechniques applied.The main relaxation dynamics in the dielectric spectra of the mixturesis found to reproduce the typical dynamic characters of the Debye relaxation observed inmonoalcohols as the mole fraction of water reaches up to70%, as the relaxation strength,dispersion and time are scrutinized. Also, the kinetic glass transition temperatures definedfrom the specific dielectric relaxation time are generally greater than the calorimetric ones,likewise in other Debye liquids. The dielectric relaxation of the mixtures ofN-ethylacetamide and1,2-propanediamine (a non-Debye liquid) and2-ethyl-1-butanol (aDebye liquid) is detected as a contrast experiment. The similarity of the dielectricdynamics in water and monoalcohols implies the possibility of the presence of chain-likeassociation in water. The observation of the Debye relaxation in water in our study canpromote not only the investigation in the nature of the Debye relaxation, but also the fieldof molecular behavior of water.