Preparation of gel-silica/ammonium polyphosphate core-shell flame retardant and properties of polyurethane composites

A novel intumescent gel‐silica/ammonium polyphosphate core‐shell flame retardant (MCAPP), which contains silicon, phosphorus, and nitrogen, has been prepared by in situ polymerization. The structure of MCAPP was characterized by Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS). The properties of MCAPP were investigated by water solubility, hydrophilicity, and morphological determination. The flame retardancy and thermal stability of polyurethane (PU) composite with MCAPP were evaluated by limiting oxygen index (LOI), UL‐94 test, cone calorimetry, and thermogravimetric analysis (TGA). The results showed that MCAPP could decrease the heat release rate (HRR) and increase the thermal stability of PU materials greatly. Finally, water‐resistant properties of PU/FR composites were also studied. Copyright © 2010 John Wiley & Sons, Ltd.