Temperature Rising Elution Fractionation of Polypropylenes Produced by Heterogeneous Ziegler-Natta Catalysts Containing Different Internal Donors

Ethyl benzoate (EB), bis(2-ethyl hexyl) sebacate (BEHS), di-n-butyl phthalate (DNBP), and bis(2-ethyl hexyl) phthalate (BEHP) were employed as internal electron donors of heterogeneous Ziegler-Natta catalysts and the obtained polypropylene (PP) samples were fractionated by temperature rising elution fractionation (TREF). The influence of different internal donors on the tacticity distributions of PPs was compared. PPs have narrower tacticity distributions with aromatic esters. Based on TREF results, different interactions of internal donor, which may depend on their structures, were proposed. The effects of internal donors on microstructure of the fractions, especially the first fractions, were examined.