Investigation of cure kinetics in a system with reactant evaporation: Epoxidized soybean oil and maleic anhydride case study

• »Green« epoxidized soybean oil was used in the study focused on the cure kinetics.
• Useful process for kinetics study of reaction systems involving evaporation is shown.
• Due to the maleic anhydride evaporation the combination of DSC and TGA was used.
• The Šesták–Berggren autocatalytic model was applied in the mathematical modeling.
• The content of catalyst AHMT had little effects on the cure kinetics parameters.

Cure kinetics of epoxidized soybean oil (ESO) with maleic anhydride (MAH), which evaporates during the curing process, is studied quantitatively considering MAH evaporation. Since MAH is commonly applied as a hardener for epoxy systems, it has been used also for ESO curing. As catalyst 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole in different amounts was used. Data necessary for modeling purposes were obtained by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The two-parameter Šesták–Berggren autocatalytic model was successfully applied in the mathematical modeling. The reaction orders n and m were found to be 2.275 and 0.420, respectively, and pre-exponential factor was found to be 3.91 × 106 s−1. The apparent activation energy decreased from 69.1 to 67.8 kJ/mol with increasing the amount of applied catalyst from 0.5 to 2.5 wt.% of catalyst per hundred parts of ESO/MAH mixture. The use of combination of DSC and TGA techniques revealed as a useful tool for kinetics investigations and predictions of reaction systems involving evaporation of one or more compounds.

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