Response Surface Optimization of Reduced‐ DMF Binary Solvents and Apparent Curing Kinetics of BMI /Epoxy/ DDS Resin Systems for Fiber‐Reinforced Composites

In the manufacture of fiber‐reinforced composites, bismaleimide (BMI)/epoxy resin (EP) systems are attractive matrix materials because they combine the heat resistance of BMI with the processability of EP, although their practical use is limited by reliance on highly polar amide solvents and complex curing behavior. In this work, a reduced‐DMF DMF/ethanol binary solvent system and the apparent curing kinetics of BMI/EP/DDS resin systems were investigated using Box–Behnken response surface methodology and differential scanning calorimetry (DSC). A DMF fraction of 88% was sufficient to maintain stable homogeneous solutions within the investigated composition range. Increasing EP content shifted the characteristic curing temperatures to higher values and broadened the curing‐temperature window from 40.1°C to 54.4°C, while the Kissinger activation energy increased from 91.96 to 97.76 kJ/mol. The Kissinger and Ozawa methods gave consistent apparent activation‐energy trends, indicating that the curing behavior could not be described as a simple superposition of independently curing BMI and EP components. Based on an apparent n th order kinetic model, isothermal curing windows were proposed for the three formulations. These results provide guidance for reduced‐DMF solution preparation and curing‐process design of BMI/EP/DDS resin systems for fiber‐reinforced composites.