Crosslinking of metallocenic α-olefin propylene copolymers by vacuum gamma irradiation

Metallocenic polypropylene and copolymers with 3.7, and 9.2 mol% of hexene and 3.0 mol% of octadecene comonomer content were synthesized without the presence of additives and irradiated with 60Co gamma radiation under vacuum at room temperature. Size Exclusion Cromatography and gel extraction data showed that scission reactions predominate over crosslinking in the homopolymer and that there is a dose from where crosslinking started to increase considerably, in the irradiated copolymers. Rheology also showed evidence of chain-enlargements on the copolymers by means of an increase in the viscoelastic properties of the irradiated material. - Highlight: ► Vacuum gamma irradiation of metallocenic isotactic propylene copolymers. ► We examine the radioinduced changes in rheological properties and molecular weights. ► Radioinduced crosslinking in the copolymers, without the presence of additives. ► Dependence of crosslinking with copolymer′s length and amount of short branches.