Flame retardants systems

Similar comments apply to the flame-retardant system based on the reaction of THPC and APO (108,109). 

Applications The method is in use for the determination of water extractable organics in PA6 and PA4.6, and for alkane extraction of waxes from HDPE (in nitrogen atmosphere to prevent oxidation) [156]. Ethylene-bis-stearamide (EBA) can be extracted from ABS in 30 min using intermittent extraction in this case quantitative Soxhlet extraction was not possible. Nelissen [157] has used intermittent extraction with MTBE for the analysis of the flame retarder system of Tribit 1500 GN30. 

Prospective Approaches to More Efficient Flame-Retardant Systems... 

It is our intention to point out clues, mostly from the literature, some from our own work, which suggest approaches to new flame retardant systems with greatly increased efficiency. Both vapor phase and condensed phase mechanisms will be considered. 

Flame retardants currently in use which operate by inhibiting vapor phase flame chemistry may be far from optimum. Those flame retardant systems which evolve hydrogen chloride, and perhaps even those which evolve hydrogen bromide, may be acting by little more than a physical effect (1). Some of our own work on tris(dichloroisopropyl) phosphate in polyurethane foams also suggests a physical mode of action (2). 

Certain catalytic modes have been well exploited in flame retardant systems, namely the dehydrating action of compounds which yield strong acids under flaming or smoldering conditions. Friedel-Crafts and other acid catalyzed condensation reactions have been exploited to increase char. These mechanisms don t work very well for polymers of mainly hydrocarbon character. Are there other modes of catalysis which might work better ... 

Probably the most efficient flame retardant system ever discovered for a polymer is platinum, which at 1 ppm flame retards silica-filled silicones and increases unbumed residue (Fig. 6). In a very thorough study by MacLaury at GE (37), platinum was shown to exert a catalytic action to induce coupling between chains and with the filler. The detailed mechanism is still uncertain nevertheless, the remarkable efficacy of platinum in this system supports the idea that very efficient f.r. agents may be designed by using catalysis principles. 

The principles needed to design a polymer of low flammability are reasonably well understood and have been systematized by Van Krevelen (5). A number of methods have been found for modifying the structure of an inherently flammable polymer to make it respond better to conventional flame retardant systems. For example, extensive work by Pearce et al. at Polytechnic (38, 39) has demonstrated that incorporation of certain ring systems such as phthalide or fluorenone structures into a polymer can greatly increase char and thus flame resistance. Pearce, et al. also showed that increased char formation from polystyrene could be achieved by the introduction of chloromethyl groups on the aromatic rings, along with the addition of antimony oxide or zinc oxide to provide a latent Friedel-Crafts catalyst. 

Careful attention to quantitative activity vs. concentration relationships, to the effect of interaction terms in combinations (using computerized regression analysis and experimental design), and careful observation of the manner in which one mode of action supports and reinforces another, seems likely to lead us to the next generation of highly efficient flame retardant systems. 

More recently, based on the results of an extensive series of small scale degradation studies, two additional mechanisms for the volatilization of antimony from antimony oxide/organohalogen flame retardant systems have been proposed (23,24). Of these two proposed mechanisms, [4] and [5], [4] does not involve HX formation at all and [5] suggests an important role for the direct interaction of the polymer substrate with the metal oxide prior to its reaction with the halogen compound. 

In this regard, it should be noted at this point that one of the products identified by CGC/MS from these pyrolysis reactions was SbBr3- Furthermore, the data presented concerning the importance of the polymer substrate in the degradation of the DBDPO and the proposed chain radical transfer mechanism [7] would suggest that the condensed phase chemistry could be much more important in antimony oxide/organohalogen flame retardant systems than had been previously thought. 

T. Handa, T. Nagashima and N. Ebihara, Synergistic Action of Sb2(>3 with Bromine-Containing Flame Retardants in Polyolefins. II. Structure-Effect Relationships in Flame Retardant Systems," J. of Fire Retardant Chemistry,, 37 (1981). ... 

Air Products, a manufacture of latex binders, has completed a comprehensive study of flame retardants for latex binder systems. This study evaluates the inherent flammability of the major polymer types used as nonwovens binders. In addition, 18 of the most common flame retardants from several classes of materials were evaluated on polyester and rayon substrates. Two of the most widely recognized and stringent small scale tests, the NFPA 701 vertical burn test and the MVSS-302 horizontal burn test, are employed to measure flame retardancy of a latex binder-flame retardant system. Quantitative results of the study indicate clear-cut choices of latex binders for flame retardant nonwoven substrates, as well as the most effective binder-flame retardant combinations available. 

Flammability of Binder-Flame Retardant Systems on Polyester... 

The use of flame retardants in polymers has increased dramatically in recent years, in parallel to the growth of the plastics industry ( 1 ). Data for the U.S. consumption of these chemicals during 1985 are presented in Table I. Many of the existing commercial additives, however, have problems associated with their use. In particular, certain flame-retardant systems are known to cause an increase in the amount of smoke and toxic/corrosive... 

G. Beyer, Filler blend of carbon nanotubes and organoclays with improved char as new flame retardant system for polymers and cable applications, Fire and Materials, vol. 29, pp. 61-69, 2005. 

UBA remarked that It is encouraging that there is a general trend to refrain from the use of halogenated flame retardants in products and to replace them with less problematic flame retardants or to redesign flame retardant systems, e.g. by creating greater distances to potential heat sources. ... 

N. Kaprinidis, P. Shields, and G. Leslie, Antimony free flame retardant systems containing Flamestab NOR 116 for polypropylene modelling. In Flame Retardants 2002, Interscience Communications, London, 2002, pp. 107-111. 

The evidence for the action of halogen and halogen antimony compounds in the gaseous phase is well established however halogen-containing flame-retardant systems are often twofold systems providing radical action inhibition in the gaseous phase and, at the same time inhibition in the condensed phase as will be seen in the next section. 

Hastie J. W. McBee, C. L. Mechanistic studies of triphenylphosphine oxide poly(ethylentereftalate) and related flame retardant systems NBS Final report NBSIR, 1975, pp. 75-742. 

Day, M., Suprunchuk, T., and Wiles, D. M., Combustion and pyrolysis of poly(ethylene terephthalate) II. Study of the gas-phase inhibition reactions of flame retardant systems, J. Appl. Polym. Sci., 1981, 26, 3085-3098. 

Wang, D.L., Liu, Y., Wang, D.Y., Zhao, C.X., Mou, Y.R., and Wang, Y.Z. 2007. A novel intumescent flame-retardant system containing metal chelates for polyvinyl alcohol. Polym. Deg. Stab. 92 1555-1564. 

Anna, P., Marosi, Gy., Csantos, I., Bourbigot, S., Le Bras, M., and Delobel, R. 2002. Intumescent flame retardant systems of modified rheology. Polym. Deg. Stab. 77 243-251. 

Huber, M.S., Non-halogenated flame retarded systems for olefins, Proceedings of the Spring Conference of the Fire Retardant Chemical Association, New Orleans, LA, Technomic Publishing Co., Lancaster, PA, March 25-28, 1990, p. 237. 

Jouffret, F. and Meli, G., Talc as a functional additive in flame retardant systems, in Flame Retardants 2004, London, January 27-28, 2004, Interscience Communications, Greenwich, U.K., pp. 129-132. 

Ishii, T., Kokaku, M., Nagsi, A., Nishita, T., and Kakimoto, M. 2006. Calcium borate flame retardation system for epoxy molding compound. Polym. Eng. Sci., 46(5), 799-806. 

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