Dielectric relaxation studies on molecular interaction in binary mixture of dimethylene chloride with n-methylformamide

• The complex permittivity spectra have been carried out at different temperatures using TDR.
• The peak of dielectric loss shifted toward high frequency as increasing temperature.
• The Kirkwood parameters for getting information regarding the orientation of electric dipoles in the system.
• The present work reveals the molecular interaction between unlike molecules.

The complex permittivity spectra of dimethylene chloride with N-methylformamide have been determined at 10, 15, 20 and 25 °C using time domain reflectometry (TDR) for 11 different concentrations of the system. The complex permittivity spectra shows that the dielectric constant is high in the lower frequency region and decreases with an increase in frequency and the peak of dielectric loss curves shifted toward higher frequencies when the temperature increases in the system. The dielectric parameters viz. static dielectric constant (ɛ0) and relaxation time (τ) have been obtained by the least squares fit method with Debye model. For temperature range, considered here, the dielectric constant and relaxation time increase with increasing the mole fraction of n-methylformamide. The excess permittivity and excess inverse relaxation time are found to be negative in the system.

Frequency dependence (a) dielectric permittivity (ɛ′), (b) dielectric loss (ɛ″) for various concentrations of NMF in DCM at T = 10 °C.Figure optionsDownload as PowerPoint slide