Dielectric relaxation properties of aqueous dimethylamine, trimethylamine and ethylamine using time domain reflectometry technique

Abstract

The complex permittivity spectra of dimethylamine (40 wt. % in water), trimethylamine (30 wt. % in water) and ethylamine (70 wt. % in water) have been obtained at different temperature using time domain reflectometry technique in the frequency range of 10 MHz-50 GHz. The relaxation mechanism for these systems is described by using Cole-Davidson model. The temperature dependant dielectric relaxation parameters such as static dielectric constant (ε₀), relaxation time (τ) and distribution parameter (β) have been obtained by using non-linear least square fit method. The extracted static dielectric constant (ε₀) and relaxation time (τ) values have been used to calculate thermodynamic parameter and Kirkwood correlation factor (g^eff). The enthalpy of activation ∆_actH suggests that chemical kinetic is exothermic. Entropy of activation ∆_actS suggests that the system is less ordered and Gibbs free energy of activation ∆_actG reveals the molecular reorientation for all the three systems. Kirkwood factor for DMA40, TMA30 and EA70 is greater than unity which confirms the hydrogen bond interaction and parallel orientation of dipoles in molecules.