Phosphorus flame retardant polymers

Hoang Dongquy, and Kim Jinhwan. Synthesis and applications of biscyclic phosphorus flame retardants. Polym. Degrad. Stab. 93 no. 1 (2008) 36-42. 

Protective Coatings. Some flame retardants function by forming a protective Hquid or char barrier. These minimize transpiration of polymer degradation products to the flame front and/or act as an insulating layer to reduce the heat transfer from the flame to the polymer. Phosphoms compounds that decompose to give phosphoric acid and intumescent systems are examples of this category (see Flame retardants, phosphorus flame retardants). 

Antagonism between antimony oxide and phosphorus flame retardants has been reported in several polymer systems, and has been explained on Ihe basis of phosphorus interfering with the formation or volatilization of antimony halides, perhaps by forming antimony phosphate. 

VECAP has seen significant successes and was subsequently implemented in five other European Member States, North America, Japan, and other parts of Asia. It has expanded to reduce release potential of other flame-retardants to the environment, including phosphorus flame-retardants. This program is not only a flame-retardant program it is a model program for all polymer additives. Companies participating in VECAP follow a cycle of continuous improvement. This starts with a commitment to the Code of Good Practice and verification of the actual... 

Padbury, S.A., Horrocks, A.R., and Kandola, B.K. 2003. The effect of phosphorus-containing flame retardants and nanoclay on the burning behaviour of polyamides 6 and 6.6. Proceedings of the 14th Conference Advances in Flame Retardant Polymers, Stamford, Norwalk, CT Business Communications 2003. 

Weil, E. D. Phosphorus Based Flame Retardants, in Flame Retard. Polym. Mater. 1978, 2, 103-133 Levin, M. Atlas,... 

Liu, Y. and Wang, Q. Melamine cyanurate-microencapsulated red phosphorus flame retardant unreinforced and glass fiber reinforced polyamide 66. Polymer Degradation and Stability, 91,3103-3109 (2006). 

Fyrolflex BDP from Akzo Nobel Chemicals has been shown to exhibit higher thermal properties and hydrolytic stability than other aryl phosphates, and to provide similar or better fire retardant performance than RDP. It is a bisphenol A bis(diphenyl phosphate) compound that provides good physical properties in formulations based on PC/ABS, HIPS and polyphenylene oxide/HIPS blends. Upon thermal decomposition of the flame-retarded polymers, phosphorus tends to accumulate in the solid residue, a result which indicates that the primary FR action of BDP is most likely to be in the condensed phase. 

Red phosphorus can be handled by encapsulating it in a thermosetting polymer with a dust suppressant, but for safety reasons it is usually supplied as a masterbatch for compounding by conventional means. The raw element is susceptible to ignition by sparks or by overheating, although it is not spontaneously flammable like the white variety. If exposed to moisture, it releases toxic phosphine that tends to be converted to phosphate. Light coloured products cannot cmrently be achieved with red phosphorus flame retardant additives. 

Clariant businesses are organised into five divisions pigments and additives masterbatches textile, leather and paper chemicals functional chemicals, and finally life science and electronic chemicals. Several polymer additive products have been mentioned already in Chapter 5. They include waxes, UV and light stabilisers, antioxidants, antistatic agents, flame retardants and phosphorus flame retardants. Some additives are targeted at other industries besides plastics. The company claims to be the world leader in pigments. 

D.Y. Wang, Y.P. Song, L. Lin, X.L. Wang, YZ. Wang, A novel phosphorus-containing poly(lactic acid) toward its flame retardation. Polymer 52 (2) (2011) 233-238. 

An analysis of the percentage of phosphorus in the residue after combustion of polymer materials shows that phosphorus can remain in the condensed phase, almost completely or partially, or that it can completely vaporize [76,77]. The latter phenomenon depends not only on the chemical nature and initial concentration of the phosphorus flame retardant but also to a high degree on the nature of polymer substrate and the structure of the material. The relationship between the amount... 

It has been demonstrated with numerous examples that many phosphorus flame retardants of the reactive and additive types contribute to the formation and increase of yield of nonvolatile carbonized residues during the pyrolysis and combustion of polymers. The detailed mechanism of this effect is not clear, as is the case with the mechanism for the carbonization of polymers. 

An analysis of the published data suggests that phosphorus flame retardants or products of their transformation serve as agents and catalysts for the substituent detachment reactions in the macromolecular chain, for cyclization reactions and for other reactions ofpolymers. As has already been mentioned, such reactions favor the formation of the carbon skeleton. Pyrolytic dehydrogenation reactions and dehydrohalogenation reactions of organic compounds are aided by the presence of phosphorus compounds. In this case, one of the most important factors to be considered is the relationship between the chemical structure of phosphorus-containing compounds and their reactivity, which determines the specific interaction with a polymer substrate under the conditions of its preliminary treatment and combustion. 

The most widely studied reaction involves the effect of phosphorus flame retardants on cellulose materials. In the presence of phosphorus-containing compounds, the decomposition of cellulose occurs in such a way that a decrease is observed in the amount of fuel gases and an increase in the amount of char residue. The amount of char residue can attain a value of almost 80% of a polymer s... 

The study of nonvolatile residues after pyrolysis and combustion of phosphorus-containing polymer systems indicates the presence of acids of phosphorus [77, 79]. Additional possible schemes of phosphoric acid formation during the pyrolysis of polymers containing inorganic derivatives of phosphorus flame retardant will be given below ... 

Hdrold Sebastian. Phosphorus flame retardants in thermoset resins. Polym. Degrad. Stab. 64 no. 3 (1999) 427-431. 

Toldy Andrea, Szolnoki Beata, Csontos Istvan, and Marosi Gyorgy. Green synthesis and characterization of phosphorus flame retardant crosslinking agents for epoxy resins. J. Appl. Polym. Sci. 131 no. 7 (2014) 40105-40112. 

Polymers containing halogen or phosphorus also showed increased oxygen indices, — for example polyvinyl chloride (01=45) vs. polyethylene (01=18). Of course, the principle of intentionally adding halogen or phosphorus compounds to polymers is one of the main approaches to flame retarding polymers. 

If the polymer cannot be involved in the charring because of the absence of reactive groups, a highly charring coadditive is used in combination with the phosphorus flame retardant. The coadditive is usually a polyol, which can undergo... 

If conditions are right, phosphorus-based molecules can voIatiHze and are oxidized, producing active radicals in the flame. On the other hand, phosphorus flame retardants tend to react with the polymer or to oxidize to phosphoric acid in the condensed phase. This favors mostly condensed-phase mechanisms. It is challenging to design a phosphorus-based flame retardant that will volatilize into the flame at relatively low temperatures but wiU not be lost dnring polymer processing. 

The LOI behavior of phosphorus-containing siliconized epoxy followed the same trend as that of siliconized epoxy system. Epoxy and siliconized epoxy materials cured with the phosphorus diamine curative exhibited the maximum LOI value of 42, which maybe due to the consequence of the char enrichment of phosphorus and the char protecting effect of silicone to exhibit the synergistic effect of both silicone and phosphorus on LOI enhancement [50-54]. Thus simultaneously incorporating silicone and phosphorus into epoxy resin would render these epoxies as flame-retardant polymers and can be rated as the best flame retardant material. 

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