| Abstract: | Ethylene/propylene copolymers were obtained with vanadium-based catalysts. Different aluminium alkyls were employed as cocatalyst: Al(C2H5)2Cl/promoter, Al(i-C4H9)3, Al(n-C6H13)3. and Al(n-C8H17)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, 13C–NMR analysis and fractionation. AIR3 afforded a polymerization activity that was much higher with respect to Al(C2H5)2Cl/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(C2H5)2Cl/promoter and with a high-yield Ti-based catalyst is also presented. |
