Development and Validation of a Global Isothermal Curing Kinetic Model via Simultaneous Multi‐Temperature Fitting for Benzoxazine‐Modified Phenolic Triazine Resin

ABSTRACT To address the insufficient prediction accuracy of the traditional isothermal curing model arising from temperature fluctuations during the isothermal curing stage of benzoxazine‐modified phenolic triazine resin (PT/BZ resin), this study develops a global isothermal curing kinetic model with a simultaneous multi‐temperature fitting (SMTF) method based on isothermal differential scanning calorimetry tests and the Levenberg–Marquardt algorithm. The prediction error distributions of the improved isothermal curing model, the traditional isothermal curing model, and the dynamic curing kinetic model have been compared and analyzed. The results show that the improved isothermal model for PT/BZ resin exhibits excellent prediction accuracy in the temperature range of 205°C–215°C. In particular, the root‐mean‐square error of curing prediction at the boundaries of the isothermal temperature range (205°C and 215°C) is reduced by approximately 13% compared with the traditional model, demonstrating better prediction capability for the isothermal curing process with temperature drift. This study expands the applicable temperature range of the existing isothermal curing model method and fills the gap in the quantitative characterization of the isothermal curing behavior of PT/BZ resin. Meanwhile, it demonstrates the prominent advantages of the SMTF method in achieving wide‐range, high‐precision prediction of the isothermal curing process for high‐temperature curing thermosetting resins.