Dielectric analysis of poly(methyl methacrylate) zinc(II) mono-pinacolborane diphenylporphyrin composites

Poly(methyl methacrylate) (PMMA) composites were made from a polar metalloporphyrin [5-(4',4',5',5'tetramethyl[1 ',3 ',2 ']dioxaborolan-2 '-yl)-10,20-diphenylporphyrinato]zinc(II) (Zn(II)Bpin-DPP) in select weight % (wt%). Differential Scanning Calorimetry (DSC) showed that porphyrin acted as an antiplasticizer raising the glass transition (Tg) from 105 degrees C to 123 degrees C. Dielectric Analysis (DEA) was performed in the frequency range of 0.3 Hz to 100 kHz between 150 and 270 degrees C. Permittivity (epsilon'), loss factor (epsilon '') and dielectric response of beta (alpha), alpha beta (alpha beta), and conductivity relaxations were studied. Previous DEA data was limited to 190 degrees C. This study brings analysis to 270 degrees C which is start point for the first part of PMMA degradation. Thus forwarding DEA can be used to evaluate PMMA degradation. The electric modulus formalism is used to reveal the beta and conductivity relaxations. The apparent activation energies (E-a) for the molecular relaxations are presented. AC (sigma(AC)) and DC (sigma(DC)) conductivity are also evaluated. (C) 2010 Elsevier Ltd. All rights reserved.