Water Resistibility of Microencapsulation Ammonium Polyphosphate and Its Flame Retardancy in Polypropylene

Ammonium polyphosphate(APP) was encapsulated with melamine formaldehyde resin(MF) forming capsules(MAPP).When the mass ratio of APP/MF was 3/1,the solubility of the capsules in water at 50 ℃ was 0.052 g/100 mL,reduced 78 % compared to APP;the intumescent degree reached 78.6 cm3/g.The MAPP capsules were introduced into polypropylene as an intumescent flame retardant.The thermal analysis indicated that the degradation of PP/MAPP was more rapidly with reduced heat release compared to neat APP.Due to the formation of porous carbon layers,the flame retardancy of PP/MAPP was better than that of PP/APP.When the mass ratio of PP/MAPP was 70/30,its oxygen index reached 30.6 %.