Abstract: 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 ㎝3/g. The MAPP capsules was 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 MAPP/PP was better than that of PP/APP. When the mass ratio of PP/MAPP was 70/30, its oxygen index reached 30.6 %.

Key words: melamine formaldehyde resin, ammonium polyphosphate, microencapsulation, water resistibility, flame retardancy, polypropylene