The dielectric relaxation behavior of miscible poly(4-vinylphenol)/poly(ethyl methacrylate) (PVPh/PEMA) blends has been studied using broad-band dielectric spectroscopy in the frequency domain from 10-2 to 107 Hz and at temperatures between 30 and 180 °C. The α and β processes are resolved from the dielectric spectra by modeling with Havriliak-Negami (HN) functions. PVPh enhances the splitting between the α and β processes and provides a better understanding of the splitting and merging mechanism. Arrhenius plots support the proposal that the α and β processes have the same molecular origin above the merging temperature. The local β process in the blends originates from side-chain rotation of PEMA and is only slightly influenced by PVPh. On the other hand, the α process includes contributions from both components, and its relaxation time increases rapidly with PVPh concentration. However, a fragility plot reveals that the presence of PVPh does not change the cooperativity beyond shifting Tg for the blends, which is inconsistent with the energy landscape model. The relaxation time for the merged αβ process also increases significantly as a result of the participation of PVPh. Because of the strong hydrogen bonding between PEMA and PVPh, the blends exhibit only slight dielectric broadening or concentration fluctuations.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry