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Summary: We found that the spherulite structure of polypropylene (PP) significantly influences the stability of PP by affecting the behavior of stabilizers. Smaller spherulites resulted in more homogeneous dispersion of stabilizers and their slower release into air, so as to elongate the lifetime of PP. Moreover, chemically and physically weak spherulite boundaries were selectively oxidized in the presence of stabilizers. The significance to control higher order structures on the stabilization of PP is reported.

Preservation of initial polymer/catalyst particle morphology under air, was examined using stopped‐flow Ziegler–Natta polymerization with various quenching conditions and post‐chemical treatments. The exposure of the initial particles to air caused the fast formation of cracks on the surface, finally leading to significant reformation of the particle shape, when polymerizing particles were washed with heptane at −65 °C under N2 or under CO2. On the other hand, when the particles were washed with heptane containing an appropriate amount of tetrahydrofuran under CO2, the particle morphology under air was almost completely maintained even after 1 h exposure. The present results are useful for various ex situ characterizations of unstable initial polymer/catalyst particles.