Nanocomposites based on thermoplastic aromatic polyimides with cerium dioxide nanoparticles: dielectric spectroscopy

The molecular mobility of films of thermoplastic aromatic polyimides and nanocomposites based on them with 3% cerium dioxide has been studied by dielectric spectroscopy. Three relaxation regions of dipole polarization were found for the initial polyimides, $\gamma$ and $\beta$ (in the glassy state) and $\alpha$ (transition to a highly elastic state).The introduction of 3% cerium dioxide into the matrix polyimide leads to the suppression of the $\gamma$ process and to the appearance in the spectra of nanocomposites, along with the $\beta$ process, of the second relaxation process $\beta_1$.The temperature dependences of the relaxation time for the $\gamma$, $\beta$ and $\beta_1$ processes are linear and correspond to the Arrhenius equation, and for the $\alpha$ process are curved and described by the Vogel–Tamman–Hesse equation. The interpretation of the molecular mechanisms of the observed processes is given.