Thermomechanical Characterization of High <i>T</i>_g Disulfide-Containing Thermoplastic Polyimides

Covalent adaptable networks are frequently studied as alternatives to conventional thermosetting polymers because they can be recycled and reprocessed; however, the inclusion of dynamic covalent bonds within high-temperature (or high-performance) engineering thermoplastics remains largely unexplored. In this work, dynamic disulfide-containing thermoplastic polyimides were synthesized and compared to nondynamic thermoplastic polyimides. The thermomechanical properties of these polymers were examined by utilizing several techniques, including thermogravimetric analysis, differential scanning calorimetry, along with the use of the rheometric quartz crystal microbalance, and traditional dynamic mechanical analysis. The resulting experimental data suggest that the thermal stability of the dynamic compositions was slightly reduced in comparison to the nondynamic analogs, but the dynamic compositions exhibit a similar mechanical response under service conditions. The dynamic compositions also demonstrated significantly easier reprocessability via compression molding than their nondynamic counterparts.