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 T 0 = 36 °C, ɛ″(PMMA) = 0.26 at T 0 = 65 °C, ɛ″(PMαCl) = 0.45 at T 0 = 140 °C and ɛ″(PVAc) = 1.6 at T 0 = 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 T 0 = 83 °C, with a polynomial fitting error P = (−9 to −15 °C).