Many thermoplastic polymers are semi-crystalline; that is, they consist of amorphous regions and crystalline regions. In the amorphous regions, the polymer chains exist in a random pattern; in the crystalline regions, the polymer chains are in a regular, periodic pattern. The degree of crystallinity, and the size and physical arrangement of the crystallites, have a significant effect on the physical and mechanical properties of the polymer - and on organic coatings based on these polymers. Polyvinylidene fluoride (PVDF) is a thermoplastic, semi-crystalline polymer. Therefore, the properties of coatings based on PVDF, such as HYLAR ® 5000, are affected by the degree of crystallinity.
It is well known that polymer molecules possess the ability to crystallize; that is, the polymer chains arrange themselves in a periodic pattern. The extent to which crystallization occurs depends on the type of polymer, its molecular microstructure and its thermal history. Most polymers that are thermodynamically predisposed to crystallize do not totally crystallize, but only partially crystallize.