The Role of Phosphate Ester as a Fire Retardant in the Palm-Based Rigid Polyurethane Foam

Palm-based polyurethane containing phosphate ester (PE) as fire retardant has been developed. This study was conducted to investigate the effect of PE inclusion into palm-based polyurethane (PU) system onto the mechanical and burning property of the PU. The PE was synthesized via ring-opening hydrolysis between phosphoric acid (H ₃ PO ₄ ) and epoxy. The synthesis was conducted at 60–70 °C with varying concentration of H ₃ PO ₄ at 2.5, 5.0 and 7.5 wt.%. It was then added into the PU system at 0, 5, 10 and 15 wt.%. Density of the PU foam was in the range of 45–50 kg·m ⁻³ . PE increased the compression strength and modulus of the PU. The highest compression stress (1441 kPa) and modulus (7733 kPa) were discovered with the addition of 10 wt.% PE. Burning properties showed that the addition of PE has decreased the burning rate of the PU foam. PU with PE synthesized from 5.0 wt.% H ₃ PO ₄ showed excellent burning properties with the lowest burning rate (0.047 cm·s ⁻¹ ) compared to control PU which was at 0.119 cm·s ⁻¹ .