Multi‐Core‐Shell Carbon Microsphere@Layered Double Hydroxide@Tea Polyphenol Structure with Synergistic Charring and Interfacial Compatibility for Flame‐Retardant and Smoke‐Suppressant Polypropylene

ABSTRACT The inherent flammability and high smoke release of polypropylene (PP) have limited its widespread application in household appliances, automobiles, and building pipelines. To address these limitations, using carbon microspheres derived from acid‐washed calcium carbide furnace dust (HCD) as the core and sequential coatings of NiCo‐layered double hydroxide (LDH) and tea polyphenols (TP), a multi‐core‐shell flame retardant (HCD@LDH@TP) was conducted. Incorporating 10 wt% HCD@LDH@TP into PP enabled the composites to attain a UL‐94 V‐1 rating, together with a limiting oxygen index of 26.7%. Compared to neat PP, it also exhibited a 38.1% reduction in peak heat release rate (pHRR) and a 39.3% decrease in peak smoke production rate (pSPR). HCD@LDH@TP employs HCD as a carbon skeleton, synergistically building a strong char layer through LDH‐catalyzed charring and TP‐induced crosslinking densification, while the gas‐phase dilution effect further contributes to efficient flame retardancy. Moreover, the PP/HCD@LDH@TP composites preserved acceptable mechanical integrity for practical applications, with a tensile strength of 17.3 MPa and an elongation at break of 61%. This work offers a sustainable route to convert hazardous industrial dust into effective flame‐retardant additives for PP composites in automotive, appliance, and pipeline applications.