Achieving superior low-temperature mechanical performances by nacre-like alternating microlayered structures in PP/POE-based pipes

The poor low-temperature mechanical performance significantly constrains the use of polypropylene (PP) pipe in frigid climates. Here, the PP/POE-based pipes were successfully manufactured using an independently-developed microlayer pipe coextrusion technology, including 8-, 32–, 128-, and 512-layer. The low-temperature mechanical performance of the 512-layer pipe is significantly improved, compared with the blend pipe, its drop hammer impact damage energy and axial tensile breaking energy are increased by 200% and 1100%, respectively. The results from DSC, WAXD, and SAXS indicate that all the microlayer pipes and the blend pipe have almost the same crystal structure. Therefore, the unparalleled low-temperature mechanical performance is attributable to the ultrathin microlayer structures, which dissipated energy by morphological variation of the dispersed phase POE and the effective initiation and termination of craze. Briefly, the self-developed microlayer pipe coextrusion technology provides an effective strategy for the preparation of low-temperature mechanical performance robust PP pipe, and provides a simple and universal method for building an ideal polymer pipe material.