In Situ Growth of Ce-UiO-66-NH ₂ on Ammonium Polyphosphate for Synergistic Enhancement on Fire Safety and Mechanical Performance

A Ce-based metal organic framework hybrid flame retardant (Ce-UiO66-APP) was synthesized via in situ growth of Ce-UiO-66-NH2 on the surface of ammonium polyphosphate (APP) and combined with a phosphoramide derivative (DPPIP) to develop halogen-free ABS composites. The resulting ABS achieved a limiting oxygen index (LOI) of 28.0% and UL-94 V-0 rating, together with significant reduction in the peak heat release rate (pHRR) and the peak smoke production rate (pSPR) by 74.7% and 65.0% compared to pure ABS, respectively. The flame-retardant mechanism indicated that the catalytic role of cerium ions up to 530 °C changed the thermal-degradation paths of DPPIP/ABS composites, promoting the formation of more protective charring layers and noncombustible gases during combustion. Moreover, owing to the improved interfacial compatibility imparted by the nanoarchitecture of Ce-UiO-66-NH2, the notched impact strength of the Ce-UiO66-APP/DPPIP/ABS composite was 11.4% higher than that of the APP/DPPIP/ABS composite, along with good retention of tensile and flexural properties. This study provided an effective strategy for designing high-performance and halogen-free flame-retardant ABS composites through interfacial and catalytic engineering.