Fire retardancy of polyurea and silylated α-zirconium phosphate composites with ammonium polyphosphate

The thermal stability and fire performance of polyurea with silylated α-zirconium phosphate and ammonium polyphosphate are studied. The addition of ammonium polyphosphate reduces the thermal stability of the composites with and without silylated α-zirconium phosphate. The peak heat release rate reduction is lower in microscale combustion calorimetry than in cone calorimetry, which suggests that some physical process, like the formation of a barrier, is the process by which fire retardancy is obtained. Based on cone calorimetry, the peak heat release rate reduction does not depend on the loading of the silylated zirconium phosphate, and the combination with ammonium polyphosphate is less effective than ammonium polyphosphate alone.