Thermally stimulated current depolarization (TSC), dielectric, and differential scanning calorimetry (DSC) techniques were used to study crystallization and molecular relaxations in poly(aryl ether ketone ketone) (PEEK). The a relaxation, associated with the glass transition (Tg = 155 °C), was studied with TSC before and after crystallization, showing that crystallinity substantially hinders amorphous relaxations, consistent with DSC analysis of the glass transition. Thermal peak cleaning was used to deconvolute the global TSC spectra, giving apparent activation energies Et over the range -120 to +240 °C. Comparison of analysis schemes to obtain activation energies either by numerical integration or by fit of the raw TSC spectra in current space is discussed. The mean values of £a from thermally cleaned TSC spectra were in agreement with those determined from classical Arrhenius plots of the dielectric a and ß relaxation data of In { versus l/Tmui where Tmal is the peak temperature. TSC has the advantage that values of £a can be determined at any temperature regardless of whether a specific transition is present. In the sub-Tg region from -120 to 130 °C, the activation energy increased gradually with temperature and the values of £a were found to agree quantitatively with those predicted by using Eyring's activated states equation with a zero activation entropy. The activation energies for both amorphous and semicrystalline PEEE were found to be identical over the range covered. At higher temperatures, the measured values of £a depart from the zero activation entropy line and exhibit a sharp maximum at Tt, indicating a high degree of cooperativity in the relaxations.
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