Dipole potential barrier simulation model for studying polar polymers

Thin layers of amorphous PMA, PMMA, PMαCl and PVAc were prepared using a spray pyrolysis technique. The dielectric loss ɛ″ of each polymer was measured as a function of temperature in the range 20–160 °C, at a fixed frequency of 1 kHz using a thick layer of polymer (48–61 μm) as a capacitor dielectric material. The maximum α-relaxation peak value of ɛ″(PMA) = 0.65 was observed at T0 = 36 °C, ɛ″(PMMA) = 0.26 at T0 = 65 °C, ɛ″(PMαCl) = 0.45 at T0 = 140 °C and ɛ″(PVAc) = 1.6 at T0 = 75 °C. The potential energy U between the stable levels of the dipoles was calculated from the dipole relaxation time and simulated using a polynomial fitting method. The experimental result obtained indicates the energy band shape. The maximum value of U obtained was U(PMA) = 2 eV, U(PMMA) = 0.38 eV, U(PMαCl) = −0.85 eV, and U(PVAc) = −1.4 eV. The positive and negative sign indicates the dipole direction with respect to electric field direction (within the field direction or in the opposite direction).A theoretical model for ɛ″ was developed for each polymer using the value of U obtained at the dielectric response regions (γ, β, and α) and compared with the experimental results. The maximum α-relaxation theoretical peak value of ɛ″(PMA) was observed at T = 45 °C, ɛ″(PMMA) at T = 80 °C, ɛ″(PMαCl) at T = 150 °C and ɛ″(PVAc) at T0 = 83 °C, with a polynomial fitting error P = (−9 to −15 °C).