Rate theory and relaxation map analysis of iodine-doped poly(ethyl methacrylate) composite films using thermally stimulated depolarization current-thermal sampling (TSDC-TS) technique

Iodine-doped Poly (Ethyl Methacrylate) composites have been prepared using casting method. Global TSDC of the composite samples has been investigated using TSDC-TS technique. It is found that, global TSDC spectra of pure PEMA are characterized by two relaxations. The first relaxation which is observed as a shoulder in the temperature range 324-333 K is attributed to the motion of side group and named β-relaxation. Whereas, the second relaxation is observed in the glass temperature range of PEMA at Tm= 347 K and named as dipolar relaxation, i.e., α-relaxation. On doping with iodine, a new relaxation peak has been obtained at high temperatures ~ 397-409 K, and named as space charge relaxation, i.e., ρ-relaxation. Complex TSDC spectra of PEMA-Iodine composites have been resolved into its elementary peaks using TS technique. These elementary peaks have been used to construct relaxation map (RM) of all samples using Eyring transformation. The existence of compensation phenomenon for all samples is also verified and the coordinates of each compensation point have been estimated. These coordinates are used to calculate the density of disorder (DOD) and thermal expansion coefficient of the samples. The thermodynamic parameters of the samples, such as, enthalpy, entropy and Gibbs free energy have been calculated at different poling temperatures.