Toughening Polypropylene Pipe by Tailoring the Multilayer of β-Transcrystallinity Alternating β-Spherulite

The applications of the polypropylene (PP) pipe are strongly restricted because of its poor impact toughness. However, conventional toughening methods always tend to sacrifice strength. Here, the strategy is proposed to toughen PP pipes without sacrificing strength, that is, constructing the alternatively arranged multilayers of the β-transcrystallinity and the β-spherulite layers by self-developed microlayer pipe coextrusion technology. Compared with the conventional blend pipe only composed of β-spherulites, the microlayer pipe with the multilayer super crystalline structure shows an improvement of 29% in impact toughness and comparable strength. This enhancement in the impact toughness is because the β-transcrystallinity induces the formation of the larger fan-shaped craze zone and semimolten fracture surfaces with severe plastic deformation. Therefore, this effort could be a useful reference for preparing high-performance PP pipes.