ABSTRACT
In general, all materials properties and in particular polymer properties depend on the structural organization of their molecules in space, i.e., the morphology they occupy, forming ordered crystalline phases or disordered amorphous, those which can coexist in the same piece. Polymer crystals can be formed from the molten state by thermal recrystallization, from macromolecular desolvation of polymer solutions or due to deformations which the material experiences when they are exposed to mechanical strain. Some polymers present more than one form of crystalline organization which can coexist in the same sample; however, only one of them will be the most thermodynamically stable. When comparing different crystalline structures, it is known that one of them presents a higher resistance, referred to mechanical properties, gas permeability, solvation, chemical degradation, etc., in comparison with the others. Taking this into consideration and the importance which molecular packing has on the synthesis-structure-processing-properties interrelation of polymers, the present chapter shows the characteristics and crystallization forms of the biodegradable polymers most used in the fabrication of finished products, in addition to the most employed techniques for morphological characterization of these materials. No further details will be given about the use and applications of these polymers, as these points will be surely reviewed in other chapters of the book.
