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APP Ammonium polyphosphate is an inorganic salt of polyphosphoric acid and ammonia containing both chains and possibly branching.
APP Ammonium polyphosphate's chemical formula is H(NH4PO3)nOH showing that each monomer consists of an orthophosphate radical of a phosphorus atom with three oxygens and one negative charge neutralized by an ammonium cation leaving two bonds free to polymerize.
In the branched cases some monomers are missing the ammonium anion and instead link to three other monomers.
CAS: 68333-79-9
MF: H12N3O4P
MW: 149.086741
EINECS: 269-789-9
The properties of ammonium polyphosphate depend on the number of monomers in each molecule and to a degree on how often it branches.
Shorter chains (n < 100) are more water sensitive and less thermally stable than longer chains (n > 1000), but short polymer chains (e.g. pyro-, tripoly-, and tetrapoly-) are more soluble and show increasing solubility with increasing chain length.
APP Ammonium polyphosphate can be prepared by reacting concentrated phosphoric acid with ammonia.
However, iron and aluminum impurities, soluble in concentrated phosphoric acid, form gelatinous precipitates or "sludges" in APP Ammonium polyphosphate at pH between 5 and 7.
Other metal impurities such as copper, chromium, magnesium, and zinc form granular precipitates.
However, depending on the degree of polymerization, APP Ammonium polyphosphate can act as a chelating agent to keep certain metal ions dissolved in solution.
APP Ammonium polyphosphate is used as a food additive, emulsifier, (E number: E545) and as a fertilizer.
APP Ammonium polyphosphate is also used as a flame retardant in many applications such as paints and coatings, and in a variety of polymers: the most important ones are polyolefins, and particularly polypropylene, where APP Ammonium polyphosphate is part of intumescent systems.
Compounding with APP Ammonium polyphosphate-based flame retardants in polypropylene is described in.
Further applications are thermosets, where APP Ammonium polyphosphate is used in unsaturated polyesters and gel coats (APP blends with synergists), epoxies and polyurethane castings (intumescent systems).
APP Ammonium polyphosphate is also applied to flame retard polyurethane foams.
APP Ammonium polyphosphate used as flame retardants in polymers have long chains and a specific crystallinity (Form II).
They start to decompose at 240 °C to form ammonia and phosphoric acid.
The phosphoric acid acts as an acid catalyst in the dehydration of carbon-based poly-alcohols, such as cellulose in wood.
The phosphoric acid reacts with alcohol groups to form heat-unstable phosphate esters.
The esters decompose to release carbon dioxide and regenerate the phosphoric acid catalyst.
In the gas phase, the release of non-flammable carbon dioxide helps to dilute the oxygen of the air and flammable decomposition products of the material that is burning.
In the condensed phase, the resultant carbonaceous char helps to shield the underlying polymer from attack by oxygen and radiant heat.
Use as an intumescent is achieved when combined with starch-based materials such as pentaerythritol and melamine as expanding agents.
The mechanisms of intumescence and the mode of action of APP Ammonium polyphosphate are described in a series of publications.
APP Ammonium polyphosphate is an organic salt of polyphosphoric acid and ammonia.
As a chemical, APP Ammonium polyphosphate is non-toxic, environmentally friendly and halogen-free.
APP Ammonium polyphosphate is most commonly used as a flame retardant, selection of the specific grade of ammonium polyphosphate can be determined by the solubility, Phosphorus content, chain length and polymerization degree.
The chain length (n) of this polymeric compound can be linear or branched.
Depending on the polymerization degree, there are two main families of ammonium polyphosphate: Crystal phase I APP (or APP I), and Crystal phase II APP (or APP II).
APP phase I has a short and linear chain (n < 100), APP Ammonium polyphosphate is more water sensitive (hydrolysis) and less thermally stable; actually it begins to decompose at temperatures above 150 °C.
The second family of APP Ammonium polyphosphate is the APP Phase II; which has an high polymerization degree, with n>1000, its structure is cross linked (branched), and it is an high-quality non-halogenated flame retardant.
APP phase II, Ammonium polyphosphate, has an higher thermal stability (the decomposition starts at approximately 300°C) and lower water solubility than APP I.
APP Ammonium polyphosphate Chemical Properties
Density: 1.74[at 20℃]
Vapor pressure: 0.076Pa at 20℃
Storage temp.: −20°C
Solubility: Aqueous Acid (Slightly)
Form: Solid
Color: White to Off-White
InChI: InChI=1S/3H3N.H3O4P/c;;;1-5(2,3)4/h3*1H3;(H3,1,2,3,4)
InChIKey: ZRIUUUJAJJNDSS-UHFFFAOYSA-N
LogP: -2.148 (est)
CAS DataBase Reference: 68333-79-9
EPA Substance Registry System: APP Ammonium polyphosphate (68333-79-9)
Uses
APP Ammonium polyphosphate is a specialty chemical that finds many different uses in key industries.
APP Ammonium polyphosphate, is an environment-friendly and halogen-free flame retardant.
APP Ammonium polyphosphate is the main constituent of many intumescent flame retardant systems: coatings, paints and engineering plastics.
APP Ammonium polyphosphate is used to prepare 20% Phosphorous/Nitrogen containing flame retardants, it can be used solely or in conjunction with other materials in the flameproof treatment for textiles, papers, fibers and woods.
Special treatment can be used to prepare 50% high concentration flameproof formulations required for special applications.
The most common ammonium polyphosphate fertilizers have a N-P2O5-K2O (nitrogen, phosphorus and potassium) composition of 10-34-0 or 11-37-0.
APP Ammonium polyphosphate fertilizers offer the advantage of a high nutrient content in a clear, crystal-free fluid that remains stable within a wide temperature range and stores well for long periods.
A variety of other nutrients mix well with polyphosphate fertilizers, making them excellent carriers of micronutrients typically needed by plants.
APP Ammonium polyphosphate is used to prepare a number of high-efficiency expanding flameproof coatings used in the construction industry, ships, trains, cables etc.
Also suitable for the flameproof treatment of wood, plywood, fiberboard, paper, fibers.
APP Ammonium polyphosphate are liquid fertilizers with compositions up to 11-37-0, manufactured by the reaction of anhydrous ammonia with superphosphoric acid.
Superphosphoric acid is made by the concentration of regular wet-process acid up to P2O5 concentrations of 78%.
Granular polyphosphates suitable for bulk blending are made by reacting ammonia with regular wet process acid of 52% P2O5 content and using the heat of reaction to drive off water to produce a phosphate melt of 10-43-0, with about 40% of the phosphorus in the polyphosphate form.
APP Ammonium polyphosphate as used as flame retardants in polymers have long chains and a specific crystallinity (Form II).
They start to decompose at 240 °C to form ammonia and polyphosphoric acid.
The phosphoric acid acts as a catalyst in the dehydration of carbon-based poly-alcohols, such as cellulose in wood.
The phosphoric acid reacts with alcohol groups to form heat-unstable phosphate esters.
The esters decompose to release carbon dioxide and regenerate the phosphoric acid catalyst.
In the gas phase, the release of non-flammable carbon dioxide helps to dilute the oxygen of the air and flammable decomposition products of the material that is burning.
In the condensed phase, the resultant carbonaceous char helps to shield the underlying polymer from attack by oxygen and radiant heat therefore preventing the pyrolysis of the substrate.
Use as an intumescent is achieved when combined with polyalcohols such as pentaerythritol and melamine as expanding agent.
The mechanisms of intumescence and the mode of action of APP Ammonium polyphosphate are described in a series of publications.
Due to its uncritical toxicological and environmental profile, APP Ammonium polyphosphate has the potential to widely substitute halogen-containing flame retardants in a series of applications like flexible and rigid PUR-foam and thermoplastics.
Agricultural Uses
APP Ammonium polyphosphate fertilizer is a unique liquid nitrogen-phosphorus fertilizer produced in Russia only by PhosAgro.
Maximum phosphorus availability and absorption by plants compared to traditional solid phosphorus-based fertilizers, especially on soils with high calcium carbonate content.
APP Ammonium polyphosphate ensures yield increase for different crops during foliar application.
APP Ammonium polyphosphate is most effective in dry weather conditions.
APP Ammonium polyphosphate is easy to store on farms.
