Ethylene/propylene copolymers with vanadium‐based catalysts: Cocatalyst effect

Ethylene/propylene copolymers were obtained with vanadium‐based catalysts. Different aluminium alkyls were employed as cocatalyst: Al(C 2 H 5 ) 2 Cl/promoter, Al(i‐C 4 H 9 ) 3 , Al(n‐C 6 H 13 ) 3 . and Al(n‐C 8 H 17 ) 3 . The influence of the cocatalyst on the molecular weight, the molecular weight distribution and the microstructure of the copolymers was investigated through GPC, DSC, 13 C–NMR analysis and fractionation. AIR 3 afforded a polymerization activity that was much higher with respect to Al(C 2 H 5 ) 2 Cl/nBPCC, but with the latter cocatalyst system copolymers were obtained with a more homogeneous distribution of the monomers and the absence of crystallinity. A comparison with ethylene/propylene copolymers obtained with a V(Acac) 3 /Al(C 2 H 5 ) 2 Cl/promoter and with a high‐yield Ti‐based catalyst is also presented.