Effects of temperature scanning rate and crystal nuclei density on the enthalpy and peak-temperature of crystallization

Based on the J(ohnson)–M(ehl)–A(vrami)–K(olmogorov)–equation, a new theoretical model for the description of the dependence of the crystallization peak-temperature, T p , on the temperature scanning rate and the crystal nuclei density has been developed in a preceding paper (Polymer 358 (2026) 130181) and applied to the interpretation of experimental data obtained by Fast Scanning Calorimetry. Simultaneously, it allows the determination of the fraction of the crystal phase and of the crystallization enthalpy studied in detail here. Vice versa, the model supplies us with the possibility to derive estimates for the crystal nuclei density and the steady-state nucleation rate based exclusively on measurements of the enthalpy of crystallization. Moreover, experimentally, one observes, at high temperature scanning rates, a decrease in the fraction of the crystal phase until crystallization processes vanish completely. The origin of such kind of behavior is explored and described based on the model developed by us. Estimates of the ratio of the critical temperature scanning rates preventing crystallization in heating and cooling are developed. The theoretical predictions are shown to be in excellent agreement with experimental data obtained by Fast Scanning Calorimetry.