Analysis of Flame Retardant and Mechanical Properties of Rigid Polyurethane Foam Modified With Barium Phytate and Zinc Borate

ABSTRACT Rigid polyurethane foam (RPUF) has found extensive applications in various industries. However, its inherent flammability has significantly constrained the further development of this composite material. This study focuses on enhancing the flame retardancy of RPUF through the synthesis of barium phytate (PABA) and the successful fabrication of RPUF co‐modified with PABA/zinc borate (ZB) using a one‐step method. The thermal stability, flame retardancy, and smoke suppression properties of the modified RPUF were systematically investigated through thermogravimetric analysis, cone calorimetry, and smoke density testing. The results demonstrated that RPUF‐PABA7.5/ZB7.5 (containing 7.5 wt% PABA and 7.5 wt% ZB) exhibited superior thermal stability, flame retardant, and smoke suppression performance. Specifically, compared with RPUF‐PABA15 (15 wt% PABA), RPUF‐PABA7.5/ZB7.5 exhibited a 1.1% increase in limiting oxygen index (LOI). Moreover, the peak heat release rate (PHRR) and total heat release rate (THR) were reduced by 17.16% and 19.28%, respectively, accompanied by a 5.41% decrease in smoke density (Ds) and a 3.86% increase in light transmission rate. RPUF‐PABA7.5/ZB7.5 also showed a significant improvement in mechanical properties, superior to RPUF‐PABA15. These findings provided valuable insights for future research on RPUF modification and flame‐retardant enhancement.