Influence of Nanosized Cerium Oxide on the Thermal Characteristics of Aromatic Polyimide Films

The influence of nanosized cerium oxide as an active filler on the mechanical properties and thermal stability indices and heat resistance of films of thermally stable aromatic polyimides of various chemical structures is studied. It is shown that, depending on the polyimide structure the introduction of cerium oxide nanoparticles into the film can lead to a noticeable increase or a significant decrease in the thermal stability of the material during thermo-oxidative degradation. It is found that the thermal stability of the films increases significantly when polyimides containing sulfonic groups in elementary units serve as matrix polymers. The introduction of cerium oxide nanoparticles into such polyimides leads to an increase in the thermal stability of the films in air by 20–40°C. Moreover, in an inert medium the thermal stability indices for the films of matrix polymers and nanocomposites differ slightly. For all the studied polyimides, the introduction of cerium oxide does not cause a noticeable change in the glass transition temperature but in some cases leads to limitation of the compliance of the films in the temperature range above the glass transition.