Comparison of three enthalpy relaxation models based on fictive temperature and nonlinear Adam–Gibbs formulation

Abstract

The phenomenological models based on fictive temperature and nonlinear Adam–Gibbs formulation have been widely used to describe the enthalpy relaxation kinetics. Although the parameters in Adam–Gibbs formulation are physically explicable, the reasonabilities of the parameters obtained from curve-fitting procedures have not been systematically discussed yet. In this work, differential scanning calorimetry was employed to measure the heat capacities of maltitol in both the amorphous and the crystalline states, and the data were used to generate the model parameters. Results showed that the configurational ground state plays an important role in extracting the model parameters. Selecting the crystal rather than the glass as the ground state seems to be effective to improve the reasonabilities of the fitted parameters. It suggested that even if the fit quality seems sound, the physical reasonability of the best-fit parameters still needs to be treated with caution.