Polypropylene with free-end long chain branching, process for making it, and use thereof

摘要

Disclosed is normally solid, gel-free, amorphous to predominantly crystalline, polypropylene characterized by strain hardening believed to be due to molecular chains that have substantial, free-end long branches of propylene units. Also disclosed is a process for making it by high energy radiation of linear polypropylene in a reduced active oxygen environment, maintaining the irradiated material in such environment for a specific period of time, and then deactivating free radicals in the material. Further disclosed is the use of the strain hardening polyproplene in extensional flow operations such as, for example, extrusion coating, film production, and thermo-forming.