Dielectric investigation of PEMA and PBiBMA in solutions at radio and microwave frequencies

The dielectric absorption of dilute solutions of poly(ethyl methacrylate) (PEMA) and poly (n-butylisobutylmethacrylate) (PBiBMA) in benzene has been studied at radio and microwave frequencies ranging from 10 kHz to 3 MHz and 10 GHz respectively and at temperatures from 288 K to 328 K. The Cole-Cole plot drawn from the dielectric data, ε\´ and ε" for different frequencies and temperatures exhibits a substantial distribution in relaxation processes and gives rise to α values of (0.57-0.53) and (0.42-0.39) for PEMA and PBiBMA respectively. Enthalpies of activation obtained using frequency variation for PEMA and PBiBMA have been found to be 9.6 kJ/mol and 27.2 kJ/mol respectively. The data evaluated using Cole-Cole plots for varying frequency for both systems were supported by the measurements carried out at microwave frequency using the concentration variation method of Gopala Krishna. Enthalpy values evaluated using concentration variation method have been found to be 10.4 kJ/mol and 28.0 kJ/mol for PEMA and PBiBMA respectively. The enthalpy values and other parameters obtained using frequency variation and concentration variation methods have been found to be in close agreement. Enthalpies observed here were expected arise from the internal rotation of the COO ester group