Determination of polymer crystallization kinetics with the NPK method

Since 1998, the NPK method developed by R. Serra, J. Sempere and R. Nomen is used by many research groups to simulate and even sometimes to better understand the thermal behavior of many chemical reactions. The NPK method has never been used for crystallization processes, nor pure products or polymers. It is well known that the degree of crystallization of a polymer is a function of its processing and has crucial consequences on its final properties, so a considerable number of papers have been published to describe this phenomenon. Between them, we can find the description of phenomenological models like the ones of Lauritzen–Hoffman, Avrami, Šesták–Berggren or Sbirrazzuoli or functional methods like the model-free method of Vyazovkin. Our work aims to study the applicability of the NPK method to a polymer crystallization phenomenon from thermal analytical data and to verify that the information obtained agrees with the most accepted models. This contribution shows the first results working with isotactic polypropylene crystallization during the cooling down of melt material.