Dielectric relaxation study of propylene carbonate from susceptibility and conductivity measurement under broadband electric field

Dielectric relaxation of propylene carbonate ( j ) dissolved in p-xylene, cyclohexane and n-heptane ( i ) at different weight fractions ( w j ′ s) of solutes for 28, 33 and 38 °C temperatures is studied under 3.8 GHz (S-Band), 7.2 GHz (C-Band), 10.5 GHz (X-Band) and 17.6 GHz (Ku-Band) electric field using simultaneously susceptibility ( χ ij ′ s) and conductivity ( σ ij ′ s) measurement technique within the framework of Debye model. The existence of double relaxation times τ 2 and τ 1 due to inter- and intramolecular rotation of the polar molecules is studied from measured data of χ ij ′ = ε ij ′ - ε ∞ i j , χ ij ″ = ε ij ″ and χ 0 i j = ε 0 i j - ε ∞ i j at different weight fractions w j ′ s using slope and intercept of χ o i j - χ ij ′ χ ij ′ against χ ij ″ χ ij ′ linear equation to show the monorelaxation behaviour τ 2 only. τ ’s are also estimated from the ratio of slopes of imaginary σ ij ″ ( = w ∈ 0 ∈ ij ′ ) and real σ ij ′ ( = ω ∈ 0 ∈ ij ″ ) parts of complex conductivity σ ij ∗ as well as χ ij ′ and χ ij ″ parts of complex susceptibility χ ij ∗ with w j curves along with linear slope of imaginary against real parts of both the measured data. The dipole moments μ j ′ s are measured at all the frequencies in terms of graphically obtained τ ’s from susceptibility measurement technique as well as τ ’s from conductivity measurement technique. The solute–solvent molecular associations are also predicted. Thermodynamic energy parameters are ascertained from ln( τ j T ) against 1/ T to predict the state of molecular environment surrounding the polar molecules. The estimated Debye factors reveal that the polar–non-polar mixture obeys the Debye relaxation mechanism. Sufficient penetration depth indicates development of a new simple and rapid sensor for determination of propylene carbonate concentration.