Correlation between the equilibrium and relaxation dielectric properties of 1,2-ethanediol |
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Authors: | N V Lifanova T M Usacheva V I Zhuravlev V K Matveev |
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Institution: | (1) Faculty of Chemistry, Moscow State University, Leninskie gory, Moscow, 119992, Russia |
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Abstract: | The data on the dispersion of the permittivity ?*(ω) of 1,2-ethanediol over the temperature range 161–453 K and the frequency range 0.1 Hz–150 GHz were analyzed using the Dissado-Hill cluster model. The relaxation frequency ωp = τ DH ?1 and intra-(n DH) and intercluster (m DH) correlation parameters were calculated. The energy barrier to the libration of molecular axes in clusters was found to be B DH = 2.96 kJ/mol. The apparent enthalpy of activation was determined; it increased from ΔH DH exp # = 22.18 kJ/mol to ΔH DH exp # = 129.19 kJ/mol close to the glass transition temperature. The mean dipole moments $ \bar \mu _c The data on the dispersion of the permittivity ɛ*(ω) of 1,2-ethanediol over the temperature range 161–453 K and the frequency
range 0.1 Hz–150 GHz were analyzed using the Dissado-Hill cluster model. The relaxation frequency ωp = τDH−1 and intra-(n
DH) and intercluster (m
DH) correlation parameters were calculated. The energy barrier to the libration of molecular axes in clusters was found to be
B
DH = 2.96 kJ/mol. The apparent enthalpy of activation was determined; it increased from ΔH
DH exp# = 22.18 kJ/mol to ΔH
DH exp# = 129.19 kJ/mol close to the glass transition temperature. The mean dipole moments of 1,2-ethanediol clusters were calculated; they decreased from 162920 to 18.08 D as the temperature increased from 161 to
453 K. According to approximate estimates, the number of 1,2-ethanediol molecules in a cluster /μv decreased from 72405 at 161 K to 8.04 at 453 K (μv is the dipole moment of the molecule in the vacuum), which substantiated the suggestion of the existence of a spatial structure
close to the boiling point.
Original Russian Text ? N.V. Lifanova, T.M. Usacheva, V.I. Zhuravlev, V.K. Matveev, 2008, published in Zhurnal Fizicheskoi
Khimii, 2008, Vol. 82, No. 10, pp. 1973–1981. |
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