Suppression of smoke

Park, D.H., Kim, S., and Lee, G.J., Halogen-free flame retardant cable materials Improvement of flame retardancy and suppression of smoke density, in Proceedings of the 49th IWCS/Focus International Wire Cable Symposium, Atlantic City, NJ, 2000, pp. 422-426. 

Besides the development of test methods, some relationships between the type of burning material and the smoke density have also been discovered. On this basis, a number of additives are marketed for the suppression of smoke formation from plastics. 

Smoke Suppression of Rigid HinylEsingMolybdenum Compounds, Technical Bulletin No. 2 Climax Performance Materials Corp. 

The use of fire retardants in polymers has become more complicated with the realisation that more deaths are probably caused by smoke and toxic combustion products than by fire itself. The suppression of a fire by the use of fire retardants may well result in smouldering and the production of smoke, rather than complete combustion with little smoke evolution. Furthermore, whilst complete combustion of organic materials leads to the formation of simple molecules such as CO2, H2O, N2, SO2 and hydrogen halides, incomplete combustion leads to the production of more complex and noxious materials as well as the simple structured but highly poisonous hydrogen cyanide and carbon monoxide. 

Furthermore, Hirschler (32) has investigated the smoke-reducing ability of a number of metal hydroxides and oxides, at incorporation levels of up to 40 phr in acrylonitrile-butadiene-styrene (ABS) copolymer. At the lowest additive level studied (10 phr), SnO gave a higher degree of smoke suppressancy (viz. 58%), than any of the other compounds, and loadings of at least 30 phr were found to be necessary to achieve comparable performance with either A1(0H) or Mg(0H). 3... 

Antimony trioxide and 8-stannic acid only exhibit marginal benefits in terms of smoke and CO suppression in this polymer system. 

Ouyang, Y. et al., Suppression of human IL-lbeta, IL-2, IFN-gamma, and TNF-alpha production by cigarette smoke extracts, J. Allergy. Clin. Immunol., 106, 280, 2000. 

Behavioral and emotional Nicotine has a number of behavioral and emotional effects. It increases locomotor activity, which is mediated by increased dopamine in the nucleus accumbens (Mirza 1996). Nicotine suppresses appetite and decreases weight gain in rats (Grunberg et al. 1986). Conversely, cessation of smoking causes increases in body weight. Nicotine increases sexual receptivity in female rats, but whether this occurs in humans has not been studied—or at least not formally (Fuxe et al. 1977). 

The generally accepted mechanisms for the suppression of fires and explosions by alkali metal salts such as potassium chloride, KCl potassium bicarbonate, KHCO3 and potassium carbonate,K2C03 in the form of dry powders or aerosols (smokes) involve heat absorption, endothermic decomposition and radical recombination. 

Goethite is used in flame retardants and smoke suppressants. Both laboratory and large scale pilot tests showed that goethite is the most active smoke suppressant when polymers and plastics are burned (Carty and White, 1999 Carty et al., 1999). It reduces the amount of smoke produced during pyrolysis in air of chlorinated PVC plasticized with dioctylphthalate, by changing the decomposition pathway followed by phthalate, so that benzene, which is produced in the absence of the smoke suppressant, is not formed (Carty et al., 1999). 

However with poor ventilation they seem to give more persistent smoke than compositions based on ammonium nitrate and sodium chloride. Analysis of the smoke showed it to be due to finely divided ammonium chloride suspended in moist air, and although not harmful it may be objectionable to the miners. In addition, calcium sulphate was included to suppress the smoke (J. Taylor and Gay [4]). Calcium nitrate found only a limited use as a substance for lowering the temperature of detonation flame. 

This substitution has had the foreseen consequence of suppressing the smoke from the shooting.4... 

Many other reports have demonstrated the smoke suppressing tendencies of hydrated fillers in various polymers including ethylene-propylene-diene elastomers,43 PP,38 polystyrene,49 modified polyphenylene oxide, polybutylene terephthalate, and ABS.37 In addition to suppressing smoke generation, a delay in the onset of smoke evolution is also achievable.25 Figure 7.5 illustrates smoke reductions obtained in PP. 

Reduced flammability and smoke emission Increased char promotion Reduced overall filler levels Suppression of phosphine formation by metal hydroxide... 

Hornsby, P.R. and Watson, C.L., Mechanistic aspects of smoke suppression and fire retardancy in polymers containing magnesium hydroxide filler, Plast. Rubber Process. Appl., 11,45-51, 1989. 

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