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Preparation of Ammonium Polyphosphate Form II from the System of Ammonium Orthophosphate-Urea

2000; Oxford University Press; Volume: 73; Issue: 1 Linguagem: Inglês

10.1246/bcsj.73.115

1348-0634

Makoto Watanabe, Masami Watanabe, Noriaki Narita, Makoto Sakurai, Hirokazu Suzuki,

Chemical Synthesis and Characterization

Abstract Ammonium polyphosphate (APP) form II was prepared by heating of a mixture of ammonium orthophosphates (triammonium, diammonium, and monoammonium orthophosphates) and urea at 280 to 300 °C under wet ammonia, which was made by passing air through 3 to 5% aqueous ammonia. The following reaction process is proposed: Ammonium orthophosphate → APP form I → Amorphous APP → APP form II. The addition of APP form II shortened the preparation time significantly. A wider range of concentrations (1 to 8%) of aqueous ammonia was available to prepare APP form II. The average particle size of the obtained APP form II was larger than 5 μm.