CURE RATE MODELLING FOR STRUCTURAL COMPOSITES: COMPOSITION-RESPONSIVE KINETICS FOR EPOXY-AMINE SYSTEMS

The curing rate of two-component epoxy resins is influenced by both temperature and the epoxy/amine ratio. In solid-state reactions, the apparent reaction order can deviate from chemical stoichiometry due to complex mechanisms and morphological effects. Furthermore, exact molar masses of oligomers and additive content are often unknown, especially in the presence of solvents or in composite materials. As a result, kinetic models cannot always be directly derived from reaction stoichiometry but must be obtained from experimental data using differential scanning calorimetry (DSC). The resulting models are typically expressed as single- or multi-step reactions with specific activation energies, pre-exponential factors, and reaction types. In this study, we present a method to develop a unified kinetic model capable of accounting for different initial epoxy/amine ratios. The model introduces apparent kinetic parameters with analytical dependence on mass or molar ratio of components. This enables the prediction of curing behavior across a range of compositions and thermal programs, including the simulation of heat generation in large parts where exothermic effects and self-heating are relevant. Potential applications include predictive process simulation, optimization of thick composite curing, and real-time quality control in the manufacturing of large-scale components such as structural body panels and interior parts in automotive and aerospace.