The role of nitrogen in nitrogen–phosphorus synergism

Abstract

Thermal analysis and limiting oxygen index flammability tests were used for elucidation of details in phosphorous-nitrogen synergism in cotton modified with methylol phosphonopropionamide and subsequently hydrolyzed by acid. The results indicate that not d l the phosphorus incorporated into the material is effective for flame retardancy purposes in the condensed phase. The comparison of modified and acid hydrolyzed cotton has shown the important influence of nitrogen in the structure of the flame retardant. A simplified theory of nitrogen-phosphorus synergism, considering this influence, is proposed.

Effect of phosphorus and nitrogen on flame retardant cellulose: A study of phosphorus compounds

“…Understanding of its reaction mechanism would be helpful in designing new flame retardants in the future. Several proposed mechanisms such as phosphorusnitrogen synergism and nucleophilic attack of enolate on phosphorus to increase the phosphorylation of cellulose have been proposed [4,5], however, under certain testing conditions during the pyrolysis of the material. Some model studies were carried out under hydrolytic condition with excess of water existing.…”

“…It is marketed by CIBA Specialty Chemicals under the trade name Pyrovatex CP. The effectiveness of this flame retardant has invoked several mechanism studies to answer its effectiveness [4,5], but is still not fully understood. Understanding of its reaction mechanism would be helpful in designing new flame retardants in the future.…”

Flame Retardants, Phosphorus

“…The mode of action of phosphorus-based flame retardants is probably best understood in cellulosic systems. Cellulose (qv) decomposes by a noncatalyzed route to tarry depolymerization products, notably levoglucosan, which then decompose to volatile combustible fragments such as alcohols, aldehydes (qv), ketones (qv), and hydrocarbons (qv) (7)(8)(9). However, when catalyzed by acids, the decomposition of cellulose proceeds primarily as an endothermic dehydration of the carbohydrate to water vapor and char.…”

“…The flameretardant action is believed to proceed by way of initial phosphorylation of the cellulose. Certain nitrogen compounds such as melamines, guanidines, and ureas appear to catalyze the cellulose phosphorylation step and are found to enhance or synergize the flame-retardant action of phosphorus on cellulose (8)(9)(10)(11). The nonvolatile phosphorus acids are also able to coat the char, rendering the char less permeable and protecting it from further oxidation by adsorption on or phosphorylation of reactive sites (12).…”

Chemistry of Flame Retardants: III. Aging of N-Methylol-3- dimethoxyphosphorylpropionamide and Commercial Flame Retardants for Fabrics Containing This Substance

“…Various aspects of its application and the behavior of fabrics treated with this product have been covered in numerous studies, in particular in works [11][12][13][14][15][16][17][18][19][20][21][22]. However, with respect to the chemistry of this FR, it has been inadequately investigated.…”