Comparison of analysis of dielectric spectra of PCL in the ε∗ and the M∗ formalism

The complex dielectric modulus, M∗(ω, T), for poly(ε-caprolactone) has been obtained by inverting the complex dielectric permittivity data, ε∗(ω, T) recorded in a wide temperature and frequency range. The analysis of the dielectric loss modulus spectra M″(ω, T) have been performed by using a simulated annealing Monte Carlo procedure in order to extract the relaxation parameters for each relaxation mode. Besides the local modes γ and β, the segmental α mode associated to the glass transition, the conductivity and the interfacial polarization peaks could be analyzed with a better precision than by using the conventional non-linear least squares method in ε″ domain. The merging of the α and β modes at high temperatures is much better defined due to the less significant contribution of the ionic conductivity in M∗ formalism.