| Popis: |
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, γ and β (in the glassy state) and α (transition to a highly elastic state).The introduction of 3% cerium dioxide into the matrix polyimide leads to the suppression of the γ process and to the appearance in the spectra of nanocomposites, along with the β process, of the second relaxation process β1.The temperature dependences of the relaxation time for the γ, β and β1 processes are linear and correspond to the Arrhenius equation, and for the α process are curved and described by the Vogel-Tamman-Hesse equation. The interpretation of the molecular mechanisms of the observed processes is given. Keywords: Polymer-inorganic nanocomposites, aromatic polyimides, nanoscale cerium dioxide, dielectric characteristics, transition temperatures, molecular mechanisms of dielectric processes. |
