A high-temperature resistant phosphate-phenolic composite foam with low density, high strength, flame retardant and thermal insulating properties

The development of advanced thermal protection systems for hypersonic vehicles necessitates materials that can withstand extreme conditions. Traditional phenolic foams, while providing good fireproofing and insulation, often suffer from brittleness, low mechanical strength, and insufficient high-temperature stability, limiting their application in critical environments. This study introduces a novel phosphate-modified phenolic foam (PF/NBR/P), enhanced by the incorporation of nitrile rubber (NBR) and phosphate to address these shortcomings. Through a series of experiments, including ablation tests and characterization techniques such as XRD and XPS, the performance of the composite foam was thoroughly evaluated. Key results reveal that PF/NBR/P foam exhibits a compressive strength of 0.41 MPa, a modulus of 6.58 MPa, thermal stability up to 400 °C, and a notably low peak heat release rate (PHRR) of 6.21 kW/m², with minimal toxic emissions upon combustion. The phosphate-modified phenolic foam developed in this study demonstrates enhanced thermal stability, flame retardancy, and mechanical strength, providing valuable insights into optimizing phenolic foams for advanced aerospace applications.