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polyphosphoric acid

   Also found in: Acronyms, Encyclopedia 0.01 sec.
polyphosphoric acid [ˌpɒlɪfɒsˈfɒrɪk]
n
1. (Chemistry / Elements & Compounds) any one of a series of oxyacids of phosphorus with the general formula Hn+2PnO3n+1. The first member is pyrophosphoric acid (n = 2) and the series includes the highly polymeric metaphosphoric acid. The higher acids exist in an equilibrium mixture
2. (Chemistry / Elements & Compounds) a glassy or liquid mixture of orthophosphoric and polyphosphoric acids: used industrially as a dehydrating agent, catalyst, and oxidizing agent
ThesaurusLegend:  Synonyms Related Words Antonyms
Noun1.polyphosphoric acid - a series of oxyacids of phosphorus
metaphosphoric acid - a glassy solid acid ([HPO3]n) often used as a dehydrating agent
pyrophosphoric acid - a solid acid formed by reactions of orthophosphoric acid
oxyacid, oxygen acid - any acid that contains oxygen


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Specifically, it is added to flame retardants, because they change as a result of high temperature thermal decomposition into polyphosphoric acid, (1), (2) which forms a heat resistant carbonaceous protective layer and interferes with the transport of oxygen to the burning zone.
Keywords: Polyphosphoric acid (PPA), Acylation reactions, Fries rearrangement, Hydroxyaryl Ketones, Phenol derivatives.
The flame retardancy mechanisms of RP have been described as follows: the oxidation of RP first occurs with increasing temperature, then the produced oxide reacts with the water from decomposed polymer to produce metaphosphoric acid, phosphoric acid, and polyphosphoric acid, which can cover the surface of the burning materials by a liquid film, and further promote the dehydration of polymers to form a stable char layer.
 
 
 
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