Transition and Migration of Ziegler–Natta Catalyst System in Propylene Polymerization. <scp>III</scp> . Comprehensive Analysis of the Extracts From Polypropylene Granules With Different Solvent Systems

ABSTRACT Polypropylene (PP) shows potential applications in high‐tech fields, such as energy storage and medical devices. However, the residual catalyst system and the oligomers of propylene restrict their practical application. Here, comprehensive analysis of the extracts from the as‐polymerized PP granules with different solvent systems was conducted, for achieving the ultraclean PP. The results indicated that the efficient extraction of the residual catalyst system and the oligomers of propylene could be achieved with n‐hexane as solvent. The results could be used to explore the transition and migration of Z–N catalyst system in propylene polymerization, moreover, the proposed post‐polymerization extraction strategy showed promising potential to produce ultraclean PP for hi‐tech applications.