Synthesis of Polypropylene/Poly(ethylene-co-propylene) in-situ blends using 5th generation of Ziegler-Natta catalyst

Polypropylene/poly(ethylene-co-propylene) in-reactor blends were synthesized by sequential multi-stage polymerization technique using fifth generation of Ziegler-Natta catalyst. Blends of isotactic polypropylene (iPP) (with a minimum isotacticity index (11) of 97.5%) and at least 12% ethylene/propylene copolymer were successfully synthesized. Experimental set-up and polymerization procedure are described in detail. Effect of external electron donor on catalyst behaviour was studied. The results showed that for the catalytic system investigated, using external electron donor causes a decrease in catalyst hydrogen response and productivity at both homo and copolymerization stages and an increase in the ratio between amorphous to crystalline ethylene-propylene copolymer of the blend. Furthermore, increasing the proportion of C-2 in the copolymerization stage leads to increase of both polymerization rates and the amount of ethyl ene/propylene rubber (EPR) in the blend.