Regulated Β-Phase Crystallization of Strong and Tough Polypropylene Through Hyperbranched Topology

Achieving both enhanced strength and improved toughness of polypropylene (PP) remains a significant challenge for industrial applications. The present study addresses this limitation by constructing a robust crystalline network through the strategic integration of hyperbranched topology. We demonstrate that a hyperbranched nucleating agent (HBPN) effectively induces high-content β-crystal formation in PP, which organizes into an interconnected crystalline architecture. This β-phase network significantly enhances the mechanical performance of PP, with tensile strength and notched impact strength increasing by 35.78% (to 42.5 MPa) and 140% (to 13.2 KJ/m²), respectively, compared to pure PP. Mechanistic studies reveal that the synergy between strength and toughness originates from HBPN mediated β-phase crystallization, which refines the morphology of spherulites and increases the degree of crystallinity. The hyperbranched topology of HBPN inhibits entangled PP chains and facilitates crystallization of PP chains. Thus, it contributes to efficient stress redistribution by dissipating localized energy through multidirectional load transfer, while arresting crack advancement via microvoid-induced stress relaxation. This work demonstrates an effective conceptual approach to engineering high-performance PP, unlocking its potential for various value-added applications.