Cure reaction modelling for thermosetting resin having two-step reaction peaks

When thermosetting resin changes from liquid to solid in cure process, the elasticity and volume also vary with the degree of reaction based on the tempearture history. Therefore, the accurate predictive model for the degree of reaction is necessary to set the appropriate temperature condition. Since the reaction model with multiple reaction peaks must consider the relationship of each reaction peak, it cannot be expressed only by single-reaction models proposed in the many previous studies. In this study, the reaction behavior for thermosetting resins with two reaction peaks was modeled by the reaction rate and ratio of total heat for each reaction peak. In addition, the diffusion control model for reaction which represents the decrease of the reaction rate by vitrification was applied to the reaction rate term for the second reaction peak. Furthermore, the temperature dependence of the diffusion control model was incorporated. The calculation results using the diffusion control model were agreed with non-isothermal differential scanning calorimetry (DSC) measurement data than Kamal model commonly used with or without temperature dependence. On the other hand, for isothermal measurement data, the temperature dependence diffusion control model was able to predict degree of reaction accurately at a temperature lower than the glass transition temperature.