β-Nucleated Polypropylene: Processing, Properties and Nanocomposites

Polypropylene (PP) and its allotropic forms is one of the most important polymeric materials due to its wide commercial penetration and academic interest over the last decades. The current review deals with β-polypropylene, one of the most interesting crystalline forms of PP, due to its metastable nature and the various physical properties which it presents. The introduction of β-crystals into the PP structure can be either simple or more complex procedure and several strategies are discussed in the current manuscript. Also, the physical properties of the specific material including structure-property relationships, thermal properties, and supermolecular structure are presented in detail. Additionally, the presence of β-PP in polymeric blends is evaluated and the effect of each component and preparation method on the polymorphic composition is debated. Finally, β-PP has been used as a polymeric matrix in several polymer nanocomposites, therefore the performance, polymorphic composition, and preparation methods have been also discussed in terms of the β-crystalline structure and the ultimate physical properties of the nanocomposites.