Copolymerization of ethylene with higher linear α-olefins—reactivity ratios

Copolymerization of ethylene with mixtures of linear α-olefins C₆–C₃₆ in the presence of two heterogeneous Ziegler–Natta catalysts, δ-TiCl₃–AlEt₃ and TiCl₄/MgCl₂–AlEt₃, at 90°C was studied by the GC method, and reactivity ratios for all paris ethylene–α-olefin were estimated from the data on olefin consumption in the reactions. In the case of the δ-TiCl₃–AlEt₃ system, the r₂ value decreases from ca. 0.05 for 1-decene to ca. 0.02 for α-C₂₂H₄₄ and then remains approximately constant. This change is similar to the dependence of the modified steric parameter E_S^C of the olefin alkyl group on the size of the alkyl group. In the case of the supported TiCl₄/MgCl₂–AlEt₃ system a similar variation of r₂ with the length of the alkyl group were observed but the absolute values of r₂ were six to ten times lower than those for the first catalytic system.