Formation and Alignment of Hybrid Shish-Kebab Morphology with Rich Beta Crystals in an Isotactic Polypropylene Pipe

In this work we successfully controlled formation and alignment of a crystal superstructure in an isotactic polypropylene (iPP) pipe via self-assembly of a β nucleating agent and rotation extrusion to tailor the performances of the iPP pipe. The results showed that during iPP pipe extrusion, β nucleating agents first self-assembled into the fibrous structure, and then were aligned off the axial direction through rotation of the mandrel and die in the self-designed rotation extrusion device. Accordingly, fibrils, as oriented templates, directed the epitaxial growth of iPP to yield hybrid shish-kebabs off the axial direction which was composed of β crystals, so as to achieve simultaneous hoop reinforcement and toughening of the iPP pipe.