ABSTRACT
From the inception of polymer science, it has been recognized that polymer molecules possess the ability to crystallize. The extent to which this occurs varies with the type of polymer and its molecular microstructure. The main characteristic of crystalline polymers that distinguishes them from most other crystalline solids is that they are normally only semi-crystalline. This is self-evident from the fact that the density of a crystalline polymer is normally between that expected for fully crystalline polymer and that of amorphous polymer. The degree of crystallinity and the size and arrangement of the crystallites in a semi-crystalline polymer have a profound effect upon the physical and mechanical properties of the polymer, and in order to explain these properties fully, it is essential to have a clear understanding of the nature of these crystalline regions.
