Time-temperature-transformation diagrams from isoconversional kinetic analyses applied to the processing and reprocessing of vitrimers

Abstract

In this study, we extend the application of Time-Temperature-Transformation (TTT) diagrams, typically employed to describe thermoset processing, to address both the processing and reprocessing of vitrimers. To that end, we have used thermal analysis methods to characterize the reactions governing curing and the thermoforming of a disulfide-containing epoxy vitrimer. The resulting diagrams, which account for adverse processing effects such as degradation and vitrification, exclusively rely on predictions derived from isoconversional methods. Notably, we introduce, for the first time, the application of isoconversional methods to the modeling of stress relaxation kinetics. Using these diagrams, we have identified the conditions for safe curing and thermoforming of the vitrimer. Predictions have been experimentally validated, confirming the robustness and versatility of model-free kinetic analyses.