Characterization of ethylene‐propene copolymers prepared with heterogeneous titanium‐based catalysts

Ethylene‐propene (EP) copolymers prepared with various heterogeneous titanium‐based Ziegler‐Natta catalysts, i. e., δ‐TiCl3, β‐TiCl3, and MgCl2‐supported titanium catalysts were fractionated by successive solvent extraction. Wide composition distributions were observed for all samples. Composition distributions of some samples were investigated precisely by temperature‐programmed elution column fractionation. The fractionation data showed that these copolymers are a mixture of polyethylene and of copolymers with different structures, i. e., random and block copolymers. In every sample random copolymers were found most abundantly, the propylene sequences being present only as mmmm pentads. These data suggest that random copolymer is formed on an isospecific site.