Intumescent fire-retardant systems

The efficiency of intumescent fire retardants could be enhanced by interlayers that deliver the active components to the surface (shown by two examples). The fire-retardant additives, delivered to the surface at early stage of combustion, accelerate the formation of protecting surface layer that hinders the degradation of the underlying material. This coating structure could be reinforced by an interlayer of ceramizing capability (e.g., polyborosiloxane). Phosphorus-free intumescent fire-retardant system could be formed by using such additive. 

Bertelli G, Marchetti E, Camino G, Costa L, Locatelli R. Intumescent fire retardant systems—Effect of fillers on char structure. Angew. Makromol. Chem. 1989 172 153-163. 

Camino G, Costa L, Martinasso G. Intumescent fire-retardant systems. Polym. Degrad. Stab. 1989 23 359-376. 

Camino, G., Costa, L. and Martinasso, G. Intumescent fire retardant systems. Polymer Degradation and Stability, 23, 359-376 (1989). 

Bertelli, G., Camino, G., Goberti, P., Marchetti, E., Luda, M.P., Costa, L., Structure-Char Forming Relationship in Intumescent Fire Retardant Systems, in Fire Safety Science - Proceedings of the third international symposium, G. Cox and B. Langford (eds), 1991, Elsevier Applied Science London, pp. 537-546. 

M. LeBras., Mineral fillers in intumescent fire retardant formulations - Criteria for the choice of a natural clay filler for the ammonium polyphosphate/pentaeythritol/polypropylene system, Fire and Materials, vol. 20, pp. 39-49,1996. 

Bourbigot, S., Le Bras, M., Gengembre, L. and Delobel, R. 1994. XPS study of an intumescent coating. Application to the ammonium polyphosphate/pentaerythritol fire-retardant system. Applied Surface Science 81(3) 299-307. 

F. Laoutid, L. Ferry, E. Leroy, and J.M. Lopez-Cuesta, Intumescent mineral fire retardant systems in EVA copolymer Effect of silica particles on char cohesion, Polym. Degrad. Stabil., 2006, 91 2140-2145. 

Wang, D. Y Liu, Y Ge, X. G Wang, Y. Z Stec, A., Biswas, B Hull, T. R and Price, D. 2008. Effect of metal chelates on the ignition and early flaming behaviour of intumescent fire-retarded polyethylene systems. Polymer Degradation and Stability 93 1024—30. 

Bourbrigot S, Le Bras M, Deobel R, Breant P, Tremillon JM. Carbonization mechanisms resulting from intumescence. Part II. Association with an ethylene terpolymer and the ammonium polyphosphate-pentaerythriol fire retardant system. Carbon 1995 33(3) 283-294. 

It has been pointed out recently that intumescent systems based on organic char sources may present some disadvantages. In particular, the charring reactions occurring in the intumescent process may be exothermic, thus spoiling the thermal insulating action t) ical of these fire retardant systems. Furthermore, the char obtained often lacks structural integrity, and may have low thermal resistance. 

Fire Retardent Paints. Fire retardant paints are based on chlorinated rubber and chlorinated plasticizers with added SbO. These reduce the rate of spread of flames. Addn of NH4H2PO4, PE, or dicyandiamide produces an intumescent or swelling paint that forms a thick insulating layer over the surface to which it is applied when exposed to flames Fire retardant paints do not control fires and are no substitute for an automatic sprinkler system. They are best used where the only hazard is exposed, combustible, interior finish materials or in isolated buildings where sprinklers will not be installed. The paint must be applied at the rate specified on the container if spread thinner the proper... 

Caze, C., Devaux, E., Testard, G., and Reix, T., New intumescent systems An answer to the flame retardant challenges in the textile industry, in Fire Retardancy of Polymers The Use of Intumescence, Le Bras, M., Camino, G., Bourbigot, S., and Delobel, R. (Eds.), 1998, Royal Society of Chemistry, London, pp. 363-375. 

In this chapter, we have discussed recent developments of intumescent flame-retarded materials in terms of reaction and resistance to fire. Research work in intumescence is very active. New molecules (commercial molecules and new concepts) have appeared. Nanocomposites are a relatively new technology in the held of flame retardancy. This technology gives the best results combined with conventional FRs and leads to synergistic effects with intumescent systems. Very promising developments in the synergy aspects are then expected and efforts should be continued in this way. 

An extensive study was conducted on the effect of chemical and structural aspects of zeolites on the fire performance of the intumescent system, ammonium polyphosphate-pentaerythritol (APP-PER), where a marked improvement of the fire-retardant properties within different polymeric matrices has been observed.56 58 The synergistic mechanism of zeolite 4A with the intumescent materials was investigated using solid-state NMR. Chemical analysis combined with cross-polarization dipolar-decoupled magic-angle spinning NMR revealed that the materials resulting from the thermal treatment of the APP-PER and APP-PER/4A systems were formed by carbonaceous and phosphocarbonaceous species, and that the zeolite enhances the stability of the phosphocarbonaceous species. 

Talc particles of different lamellarity and specific surface area have been incorporated into polyethylene vinyl acetate (EVA) copolymer/magnesium hydroxide (MH) composite system.63 The fire retardancy of this system has been studied and compared with formulations containing only EVA and MH and formulations containing EVA, MH, and organomodified montmorillonites (oMMT). It was observed that talc with higher lamellar index showed fire behavior similar to that of EVA/MH/ oMMT system with some intumescence. 

Melamine diborate (MB), known in the fire-retardant trade as melamine borate, is a white powder, which can be prepared readily from melamine and boric acid. It is partly soluble in water and acts as an afterglow suppressant and a char promoter in cellulosic materials. Budenheim Iberica79 claims that, in a 1 1 combination with APP, MB (10%-15%) can be used for phenolic bound nonwoven cotton fibers. In general, melamine borate can be used as a char promoter in intumescent systems for various polymers including polyolefins or elastomers. However, its low dehydration temperature (about 130°C) limits its application in thermoplastics that are processed at above 130°C. Melamine borate is also reported to suppress afterglow combustion in flame-proofing textiles with APP or monoammonium phosphate to meet the German DIN 53,459 and Nordtest NT-Fire 002.80... 

Fire-retarded materials functioning in the condensed phase, such as intumescent systems, form, on heating, foamed cellular charred layers on the surface, which protects the underlying material from the action of the heat flux or the flame. It is recognized that the formation of the effective char occurs via a... 

Duquesne, S., Le Bras, M., Jama, C., Weil, E.D., and Gengembre, L. 2002. X-ray photoelectron spectroscopy investigation of fire retarded polymeric materials Application to the study of an intumescent system. Polymer Degradation and Stability 77(2) 203-211. 

This chapter develops at first the more frequent combinations of nanoparticles that concern layered silicates associated with phosphorus compounds, as well as metallic hydroxides and halogen compounds. The association of natural layered silicates with intumescent FR (IFR) systems represents one of the main contributions of the combined use of nanoparticles and FRs. Moreover, combinations of layered silicates with other phosphorus compounds have been studied and have led to significant improvements for fire retardancy. 

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