Semi-crystalline - Thermoplastic polymers, elastomers and additives

The crystalline state of the polymers is characterized by a three-dimensional order of at least a part of the chains e, independently of the details of the structure. They are known as crystalline seeds as only partially crystallizing giving a mixed structure characterized by a crystalline melting temperature Tf and a glass transition temperature Tg always much lower than the Tf. The degree of crystallinity of polymers, which due to their regular structure and the flexibility of their chains have a greater tendency to crystallize, depends on the crystallization conditions.

A crystalline resin to solidify its chains seek to form structures called crystallites. The crystalline resins are opaque since there is no space for light to pass between the molecules.

polyamides

polyethylene

Polypropylene

polyacetal

polyethylene terephthalate

Unlike amorphous resins, crystallines have a good percentage of shrinkage which represents certain considerations in their processing to achieve good dimensional stability and avoid problems such as shrinkage and deformation by shrinkage.