Transition and Migration of Ziegler–Natta Catalyst System in Propylene Polymerization. I. Quantitative 1 H NMR Analysis of the Extracts From Polypropylene Granules

ABSTRACT Polypropylene (PP) membranes show promising applications in electric and biomedical fields. However, the residue of the Z–N catalyst system would decline their electrical properties, limiting their practical applications. To explore the transition and migration of the Z–N catalyst system in propylene polymerization, the as‐synthesized PP granules are extracted with polar solvent (ethanol) and nonpolar solvent ( n ‐hexane) respectively. The extracts are quantitatively analyzed with 1 H NMR technique. The results demonstrate that the donors in the Z–N catalyst system and the low‐molecular‐weight oligomers of propylene could be removed with both solvents, while the metal‐containing species could only be extracted with ethanol after deactivation. A secondary extraction is proposed to open a new idea for the manufacturing of ultra‐clean PP for specific high‐technology applications.