Much of the phosphorus present in crops (cereals in particular) is present as “phytate” (C6H18O24P6 see below). This form of phosphorus poses issues in agriculture and food, because it cannot be digested by mono-gastric animals (such as pigs, chickens, humans). Thus, the phosphorus content is not available, so in pig feed for example it is effectively lost to manure.
Also, phytate bonds to metal ions (complexes), thus rendering important minerals such as calcium or iron non-available in animal or human foods. Scientists in Belgium, working on BioRefineries (making valuable products from agricultural wastes and non-food by-products) are looking at turning the phytate problem into a valuable, bio-sourced PIN flame retardant. Phytate has two properties which make it potentially interesting as a PIN flame retardant: its phosphorus content and its capacity for complexing with metals (to produce phosphorus-inorganic FRs). Different phytate – metal complexes have been tested as PIN flame retardants in the bio-sourced polymer poly lactic acid (PLA), with aluminium phytate salts showing the best fire performance (up to 40% reduction in peak heat release). The authors are also testing other bio-sourced PIN flame retardants, in particular microfibers of cellulose (CNC cellulose nano crystals) treated with urea and phosphoric acid (CNC-P), and synergies of these products with the phytate salts presented above.
F. Laoutid & P. Dubois, Service des Matériaux Polymères et Composites (SMPC), Université de Mons – Materia Nova, Mons, Belgique, in PolyFlame Newsletter n°6, Oct. 2014 (in French), Société Chimique de France www.polymer-fire.com