Transition and Migration of Ziegler‐Natta Catalyst System in Propylene Polymerization. <scp>II</scp>. Comprehensive Analysis of the Extract From Polypropylene Granules With Isopropyl Alcohol/<i>n</i>‐Hexane

ABSTRACT Polypropylene (PP) shows potential application in energy and biomedical fields. However, the residue of the Z–N catalyst system limits its practical application. Here, the transition and migration of the Z‐N catalyst system in propylene polymerization were explored by the comprehensive analysis of the extract from as‐synthesized polypropylene granules with isopropyl alcohol/n‐hexane. The results indicated that the catalyst support (MgCl 2 ) and co‐catalyst (triethylaluminium) could not be extracted, while the Ti‐based active species could be partially removed with decreased Ti content of 0.07 ppm from 0.26 ppm in the as‐synthesized polypropylene granules. Moreover, the electron donors and oligomers of propylene with a relative number‐averaged molecular weight (Mn) of 5.4 × 10 3 with a PDI of 4.43 could be removed. The ultra‐clean PP could be obtained via the proposed strategy for hi‐tech applications, with lower contents of polar and odorous small molecules and oligomers.