Fusion method of model-free and model-fitting for complex reactions in accelerating rate calorimetry

•The complex kinetics with accelerating rate calorimetry data are estimated by the fusion method.•The model-free method provides references for the model-fitting method.•The model-fitting method in steps can reduce the data dimensions. At present, the kinetic approaches of accelerating rate calorimetry (ARC) are restricted to model-fitting methods, and the n-order reaction model is mainly used to estimate the kinetic parameters. However, the model-fitting method has the problems related to model selection and falling into a local optimum. To address these issues, kinetic analysis methods are introduced into ARC data treatment, and the kinetic parameters of complex reactions are solved by a model-free and model-fitting fusion method. First, the Friedman method is used to calculate the activation energy Eα. Then, Aα and the overall mathematical function f(α) are obtained through the compensation effect. It provides references for the selection of the reaction model and initial values of model fitting, and the kinetic parameters are estimated through two-step model fitting. The fitting in steps realizes the decoupling of E and A and reduces the data dimensions. These help to reduce the chance of falling into a local optimum and lower the experience requirements. Finally, numeric simulations and the experimental results showed the effectiveness of the method.