Effects of predetermined nuclei and limited transformation on polymorphic crystallization in a model polymer

Formation of different polymorphic structures plays important role in crystallization of some polymers, like polypropylene, polycaproamide, poly(vinylidene difluoride), and others. Physical properties of such materials depend on phase structure, that is, fractions of different polymorphs. Basing on the model of many-phase transitions (Ziabicki, J Chem Phys 2005, 123, 174103; Ziabicki and Misztal-Faraj, J Mater Res, 2011, 26, 1585) a model system consisting of an amorphous phase, stable solid phase, and metastable polymorphic phase was analyzed. Two effects in the kinetics of polymorphic crystallization have been analyzed: effect of the presence of universal and/or selective predetermined nuclei and limited crystallizability resulting from molecular constraints in high-molecular systems. Conditions in which different phase compositions (i.e., different proportions of individual phases) have been discussed. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012