Overall crystallization kinetics; Application to transcrystallinity
Résumé
Overall crystallization kinetics theories are described, and most known classical theories (Kolmogoroff, Avrami, Evans and Tobin) are first considered and compared. Main assumptions are pointed out in order to clearly show the domain of validity of such approaches. This analysis leads to the conclusion that Kolmogoroff, Avrami and Evans theories are equivalent (KAE theory) whereas Tobin's approach is slightly different. Some possible extensions of the KAE theory are described, among them crystallization in a limited volume and in the presence of transcrystallinity. These latter phenomena are often observed even during laboratory analysis and should not be ignored. The induced effects on DSC peaks, apparent crystallization temperature, and Avrami exponent are theoretically and experimentally demonstrated.