A novel crystal morphology of isotactic polypropylene induced by pressure vibration field: α Banded spherulite

•A novel crystal morphology (α banded spherulite) of iPP is achieved in this study.•The spherulite morphology is correlation with pressure fluctuation.•No rings could be found in the exterior of the spherulite.•The pressure vibration is indispensable to the formation of banded spherulites.•The formation mechanism of α banded spherulite is proposed.

This article reports the novel crystal morphology of isotactic polypropylene (iPP) called α banded spherulites, which were induced by a pressure vibration field and investigated through polarized light microscopy, scanning electron microscopy and atomic force microscopy. Results showed that the height profile of banded spherulite along the radius corresponded to the pressure fluctuation in the cavity. No rings were found in the exterior of the spherulites, indicating that pressure vibration with a specific intensity was indispensable for the formation of banded spherulites. This work provided a new insight into the formation mechanism of banded spherulites induced by a mechanical field.

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