Ammonium polyphosphate is an inorganic salt of polyphosphoric acid and ammonia containing both chains and possibly branching. Its 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 ammoniumcation leaving two bonds free to polymerize. In the branched cases some monomers are missing the ammonium anion and instead link to three other monomers.
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),[1] but short polymer chains (e.g. pyro-, tripoly-, and tetrapoly-) are more soluble and show increasing solubility with increasing chain length.[2]
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 ammonium polyphosphate at pH between 5 and 7.[3] Other metal impurities such as copper, chromium, magnesium, and zinc form granular precipitates.[4] However, depending on the degree of polymerization, ammonium polyphosphate can act as a chelating agent to keep certain metal ions dissolved in solution.[5]
Ammonium polyphosphate (APP) 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 is part of intumescent systems.[6] Compounding with APP-based flame retardants in polypropylene is described in.[7] Further applications are thermosets, where APP is used in unsaturated polyesters and gel coats (APP blends with synergists), epoxies and polyurethane castings (intumescent systems). APP is also applied to flame retard polyurethane foams.
Ammonium polyphosphates 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 [citation needed]. 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.[8] 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 are described in a series of publications.[9][10]
^US 4041133, Young, Donald C., "Ammonium polyphosphate production", published 1977-08-09, assigned to Union Oil Co. of California
^US 4721519, Thomas, William P. & Lawton, William S., "Stable ammonium polyphosphate liquid fertilizer from merchant grade phosphoric acid", published 1988-01-26, assigned to American Petro Mart Inc.
^US 3044851, Young, Donald C., "Production of ammonium phosphates and product thereof", published 1962-07-17, assigned to Collier Carbon & Chemical Co.
^Gowariker, Vasant; Krishnamurthy, V. N.; Gowariker, Sudha; Dhanorkar, Manik; Paranjape, Kalyani (8 April 2009). The Fertilizer Encyclopedia. John Wiley & Sons. ISBN9780470431764. Retrieved 30 June 2018 – via Google Books.
^Weil, E.D., Levchik, S.V. Flame retardants for plastics and textiles, p. 16. Hanser Publishers, Munich, Germany, 2009
^. Mindfully.org. Archived from the original on 13 September 2007. Retrieved 30 June 2018.
^US 4515632, Maurer, Alexander & Staendeke, Horst, "Activated ammonium polyphosphate, a process for making it, and its use", published 1985-05-07, assigned to Hoechst AG
^Camino, G.; Luda, M.P. Mechanistic study of intumescence, p. 48 f, in Le Bras, M.; Camino, G.; Bourbigot, S.; Delobel, R. Eds., Fire retardancy of polymers; The use of intumescence, The Royal Society of Chemistry, Cambridge, UK, 1998
^Bourbigot, S.; Le Bras, M. Intumescence flame retardants and char formation, p. 139 f, in Troitzsch, J. Ed. Plastics flammability handbook, 3rd Ed., Hanser Publishers, Munich, 2004
External linksedit
US 2950961, Striplin Jr., Marcus M.; Stinson, John M. & Potts, John M., "Production of liquid fertilizers", published 1960-08-30, assigned to Tennessee Valley Authority
US 4211546, Jensen, William C., "Process for preparation of ammonium polyphosphate", published 1980-07-08, assigned to Western Farm Services Inc.
May 05, 2024
ammonium, polyphosphate, inorganic, salt, polyphosphoric, acid, ammonia, containing, both, chains, possibly, branching, chemical, formula, nh4po3, showing, that, each, monomer, consists, orthophosphate, radical, phosphorus, atom, with, three, oxygens, negative. Ammonium polyphosphate is an inorganic salt of polyphosphoric acid and ammonia containing both chains and possibly branching Its 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 Ammonium polyphosphate Names Other names Exolit AP 422FR CROS 484CS FR APP 231 Identifiers CAS Number 68333 79 9 ChEBI CHEBI 147408 ECHA InfoCard 100 063 425 E number E452 v thickeners CompTox Dashboard EPA DTXSID3097842 Properties Chemical formula NH4PO3 n OH 2 Molar mass 97 01 g mol Appearance white powder Density 1 9 g cm3 bulk density 0 7 g cm3 Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox references 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 lt 100 are more water sensitive and less thermally stable than longer chains n gt 1000 1 but short polymer chains e g pyro tripoly and tetrapoly are more soluble and show increasing solubility with increasing chain length 2 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 ammonium polyphosphate at pH between 5 and 7 3 Other metal impurities such as copper chromium magnesium and zinc form granular precipitates 4 However depending on the degree of polymerization ammonium polyphosphate can act as a chelating agent to keep certain metal ions dissolved in solution 5 Ammonium polyphosphate is used as a food additive emulsifier E number E545 and as a fertilizer Ammonium polyphosphate APP 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 is part of intumescent systems 6 Compounding with APP based flame retardants in polypropylene is described in 7 Further applications are thermosets where APP is used in unsaturated polyesters and gel coats APP blends with synergists epoxies and polyurethane castings intumescent systems APP is also applied to flame retard polyurethane foams Ammonium polyphosphates 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 citation needed 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 8 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 are described in a series of publications 9 10 References edit 1 Archived 2010 05 22 at the Wayback Machine US 4041133 Young Donald C Ammonium polyphosphate production published 1977 08 09 assigned to Union Oil Co of California US 4721519 Thomas William P amp Lawton William S Stable ammonium polyphosphate liquid fertilizer from merchant grade phosphoric acid published 1988 01 26 assigned to American Petro Mart Inc US 3044851 Young Donald C Production of ammonium phosphates and product thereof published 1962 07 17 assigned to Collier Carbon amp Chemical Co Gowariker Vasant Krishnamurthy V N Gowariker Sudha Dhanorkar Manik Paranjape Kalyani 8 April 2009 The Fertilizer Encyclopedia John Wiley amp Sons ISBN 9780470431764 Retrieved 30 June 2018 via Google Books Weil E D Levchik S V Flame retardants for plastics and textiles p 16 Hanser Publishers Munich Germany 2009 As a flame retardant Mindfully org Archived from the original on 13 September 2007 Retrieved 30 June 2018 US 4515632 Maurer Alexander amp Staendeke Horst Activated ammonium polyphosphate a process for making it and its use published 1985 05 07 assigned to Hoechst AG Camino G Luda M P Mechanistic study of intumescence p 48 f in Le Bras M Camino G Bourbigot S Delobel R Eds Fire retardancy of polymers The use of intumescence The Royal Society of Chemistry Cambridge UK 1998 Bourbigot S Le Bras M Intumescence flame retardants and char formation p 139 f in Troitzsch J Ed Plastics flammability handbook 3rd Ed Hanser Publishers Munich 2004External links editUS 2950961 Striplin Jr Marcus M Stinson John M amp Potts John M Production of liquid fertilizers published 1960 08 30 assigned to Tennessee Valley Authority US 4211546 Jensen William C Process for preparation of ammonium polyphosphate published 1980 07 08 assigned to Western Farm Services Inc Retrieved from https en wikipedia org w index php title Ammonium polyphosphate amp oldid 1214557872, wikipedia, wiki, book, books, library,
