Melt strain hardening of polypropylenes and its relation to molecular structure: a review

Strain hardening of polymer melts is a rheological feature that improves properties of items processed by operations with pronounced extensional deformations. Thus, developments have been undertaken over the years to modify linear polypropylenes not showing strain hardening. The different ways to generate strain hardening polypropylenes are reviewed, and it is shown how rheological relations can be used for their characterization. Chemical reactions are shortly addressed, but the main focus lies