Abstract
Ammonium polyphosphate (APP) form II was prepared by heating a mixture of ammonium orthophosphate and urea at 280 to 300°C under wet ammonia which was made by passing air through 3 to 5% ammonia water. Simple dry process of the preparation of APP form V was studied and APP form V was prepared by heating a mixture of ammonium orthophosphate and urea at 330 to 340°C under wet ammonia which was made by passing air through 15 to 29% aqueous ammonia. These APPs showed an oxygen index higher than 26 when they were added to synthetic organic polymers.
