Simultaneous Enhancement of Mechanical and Dielectric Performance of Polypropylene Composites by Introducing an External Elastic Crystal

Developing recyclable high‐voltage cable insulation to replace cross‐linked polyethylene is imperative for sustainable power grids. Isotactic polypropylene is a premier candidate but is limited by its inherent stiffness and low‐temperature brittleness. While melt blending with elastomers enhances flexibility, it typically compromises ultimate tensile strength and electrical insulation integrity. This work resolves these trade‐offs by introducing an external elastic crystal into the isotactic polypropylene crystal structure. The incorporation of propylene‐based elastomers with distinct crystallization capabilities induces the formation of a unique hierarchical morphology comprising spherulites, irregular crystal regions, and amorphous networks. This optimized crystal structure significantly enhances the composite material's elongation at break and mechanical strength, while also providing the ability to suppress space charge accumulation and a high dielectric breakdown strength. This strategy offers a robust pathway for designing high‐performance, environmentally friendly materials for next‐generation high‐voltage cable applications.