On permittivity and density of the systems (tetraglyme + dimethyl or diethyl carbonate) and the formulation of Δε in terms of volume or mole fraction

Relative permittivity and density on mixing from T = 288.15 K to 328.15 K and atmospheric pressure have been measured over the whole composition range for CH3O(CH2CH2O)mCH3 polyoxyethyleneglycol dimethyl ether with m = 4 (also called 2,5,8,11,14-pentaoxapentadecane or tetraglyme) + (dimethyl or diethyl carbonate). For these systems the deviation of permittivity, Δε, changes sign depending on whether it is defined on the basis of mole fractions of volume fractions. Arguments are put forward that support the choice of the definition in terms of mole fraction. The Redlich–Kister equation has been used to estimate the binary fitting parameters and standard deviations from the regression lines were calculated. The density and excess molar volumes were fitted as a function of temperature and mole fraction to a polynomial equation. The temperature dependence of derived magnitudes, such as the isobaric thermal expansion coefficient, α  , ∂VmE∂TP,x, and ∂HmE∂PT,x were computed, due to its importance in the study of specific molecular interactions. Different traditional mixing rules have been applied to predict the permittivity of these mixtures.