Dipole potential barrier simulation model for studying polar polymers

Thin layers of amorphous PMA, PMMA, PM alpha Cl and PVAc were prepared using a spray pyrolysis technique. The dielectric loss epsilon '' of each polymer was measured as a function of temperature in the range 20-160 degrees C, at a fixed frequency of 1 kHz using a thick layer of polymer (48-61 mu m) as a capacitor dielectric material. The maximum alpha-relaxation peak value of epsilon ''(PMA) = 0.65 was observed at T-0 = 36 degrees C, epsilon ''(PMMA) = 0.26 at T-0 = 65 degrees C, epsilon ''(PM alpha Cl) = 0.45 at T-0 = 140 degrees C and epsilon ''(PVAc) = 1.6 at T-0 = 75 degrees 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(PM alpha Cl) = -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 epsilon '' was developed for each polymer using the value of U obtained at the dielectric response regions (gamma, beta, and alpha) and compared with the experimental results. The maximum alpha-relaxation theoretical peak value of epsilon ''(PMA) was observed at T=45 degrees C, epsilon ''(PMMA) at T= 80 degrees C, epsilon ''(PM alpha Cl) at T= 150 degrees C and epsilon ''(PVAc) at T-0 = 83 degrees C, with a polynomial fitting error P = (-9 to -15 degrees C). (c) 2007 Published by Elsevier B.V.