Crystallization mechanisms and relevant theories
Résumé
Some of the theories involved in the understanding of polymer crystallization are discussed. First of all, crystallization is a first-order thermodynamical transition, that can be treated using the free-enthalpy formalism. Then, crystallization is a two-step phenomenon, the respective steps being nucleation and growth. The classical nucleation theory provides a general framework for the interpretation of both homogeneous and heterogeneous nucleation An alternative approach is the sequential deposit of molecular stems, also used in the kinetic theory of growth, which induces the concept of growth regimes. Less frequently, models have tried to explain the specific features of polymer morphologies: long periods, spherulites. Among them, one can mention the models of Rault and of Padden and Keith.