Effect of Ammonium Polyphosphate on Flame Retardancy, Thermal Stability, and Mechanical Properties of Unsaturated Polyester/Phenolic/Montmorillonite Nanocomposites

In present research, the effect of ammonium polyphosphate (APP) content on flame retardancy, thermal stability, and mechanical properties of unsaturated polyester resin/unsaturated phenolic resin/montmorillonite (MMT) nanocomposites were studied. Nanocomposites were prepared via in situ mold casting technique. Flame retardancy of the nanocomposite was investigated through the UL 94 vertical burning test and limiting oxygen index (LOI) analysis. Thermogravimetric analysis (TGA) was conducted to measure thermal properties, whereas flexural and impact tests were carried out to determine mechanical properties of nanocomposites. Nanocomposites with 30 phr APP achieved the flammability rating of V-1 and LOI of 29.2%. TGA results showed that nanocomposites with 30 phr APP had the highest thermal stability. Nanocomposite prepared with 3 phr MMT had the highest flexural strength, flexural modulus, and impact strength. Thus the best balance between flame retardancy, thermal stability, and mechanical properties was achieved with MMT and APP content of 3 and 30 phr, respectively.