Fires, thermal decomposition products

Kennah, H.E. Stock, M.F. Alarie, Y.C. "Toxicity of Thermal Decomposition Products from Composites, J. Fire Sciences 1987, 5(1), 3-16. 

Electrical and electronic devices are made utilizing several various types of plastic materials, thus when discarded their waste is difficult to recycle. The plastics employed in housing and other appliances are more or less homogeneous materials (among others PP, PVC, PS, HIPS, ABS, SAN, Nylon 6,6, the pyrolysis liquids of which have been discussed above). However, metals are embedded in printed circuit boards, switches, junctions and insulated wires, moreover these parts contain fire retardants in addition to support and filler materials. Pyrolysis is a suitable way to remove plastics smoothly from embedded metals in electrical and electronic waste (EEW), in addition the thermal decomposition products of the plastics may serve as feedstock or fuel. PVC, PBT, Nylon 6,6, polycarbonate (PC), polyphenylene ether (PPO), epoxy and phenolic resins occur in these metal-containing parts of EEW. 

Chlorambucil is noncombustible, but toxic, corrosive, or flammable thermal decomposition products such as carbon monoxide, hydrogen chloride, and oxides of nitrogen may form if involved in a fire. Because of possible aquatic toxicity concerns. 

FORMYL TRIBROMIDE (75-25-2) CHBrj Noncombustible liquid. Violent reaction with chemically active metals, acetone, calciiun, strong caustics, potassium, potassium hydroxide, sodium hydroxide. Increases die explosive sensitivity of nitromethane. Incompatible with crown polyediers, sodium-potassium alloys. Forms fiiction- and shock-sensitive compounds with hthium. Aqueous solution is a medium-strong acid. Liquid attacks some plastics, rabber, and coatings. Corrosive to most metals in the presence of moisture. Thermal decomposition products include highly toxic carbonyl bromide and hydrogen bromide fumes. On small fires, use dry chemical powder (such as Purple-K-Powder), foam, or CO2 extinguishers. 

Fires involving materials treated with anti-ChEs or bulk pesticides stores (CM and OP) may release both the unaltered anti-ChE and thermal decomposition products. Also, certain phosphorus-based fire retardants that arc subjected to heat and flame in a fire may result in the generation of anti-ChEs and other toxic materials. Thus, although fire retardants may slow the rate of fire progression, their involvement in a conflagration may result in an increase in the toxic potency of combustion products (Purser, 1992). For example, polyurethane foams treated with a trimethylol propane polyol base containing phosphoms-based retardants formed a highly neurotoxic combustion product [irimethylolpropane phosphate (TMPP) Petajan et at., 19751. 

Sakai, T., and A. Okukubo. 1979. Application of a test for estimating the relative toxicity of thermal decomposition products. In Eire Retardant Proceedings of the European Conference on Flammability and Fire Retardants, ed. V. M. Bhatnagar, pp. 147-53. Westport, CT Technomic. 

Storage and warehousing norms should indicate that PIF is not explosive but catches fire without burst and burns with a smoky flame, forming a melt and thermal decomposition products. 

D. Thermal-breakdown products. Under fire conditions, many organic substances will break down to other toxic substances. The amounts, kinds, and distribution of breakdown products vary with the fire conditions and are not easily modeled. Information on the likely thermal-decomposition products is included because of their importance in the assessment of health hazards underfire conditions. 

Purser, D. A. and Grimshaw, P. The incapacitative effects of exposure to the thermal decomposition products of polyurethane foams. Fire and Materials, 8, No. 1, 10 (1984)... 

DIN 53436 (2003) Construction Materials Fire Testing Producing Thermal Decomposition Products from Materials in a Air Stream and Toxicological Testing. 

Solutions of these fire retardant formulations are impregnated into wood under fliU cell pressure treatment to obtain dry chemical retentions of 65 to 95 kg/m this type of treatment greatly reduces flame-spread and afterglow. These effects are the result of changed thermal decomposition reactions that favor production of carbon dioxide and water (vapor) as opposed to more flammable components (55). Char oxidation (glowing or smoldering) is also inhibited. 

For technical purposes (as well as in the laboratory) RuOz and Ru based thin film electrodes are prepared by thermal decomposition techniques. Chlorides or other salts of the respective metals are dissolved in an aqueous or alcoholic solution, painted onto a valve metal substrate, dried and fired in the presence of air or oxygen. In order to achieve reasonable thicknesses the procedure has to be applied repetitively with a final firing for usually 1 hour at temperatures of around 450°C. A survey of the various processes can be found in Trasatti s book [44], For such thermal decomposition processes it is dangerous to assume that the bulk composition of the final sample is the same as the composition of the starting products. This is especially true for the surface composition. The knowledge of these parameters, however, is of vital importance for a better understanding of the electrochemical performance including stability of the electrode material. 

The products of thermal decomposition of organic-mineral fertiliser mixtures were studied by IR spectroscopy, and implications for fire and explosion hazards considered. 

It was found that the amount of energy needed for the room fire to cause thermal decomposition of the PVC products in the plenum was larger than that needed to take the room to flashover. Furthermore, if the PVC products did eventually decompose or burn, somehow, they would cause a lethal smoke concentration only significantly later than a lethal (by toxicity) atmosphere had already been created by the fire itself. Thus, the PVC products did not add any significant fire hazard to that caused by the room fire. 

It is of interest to calculate, too the time required for both the fire itself and the thermal decomposition of the plenum PVC products to produce a lethal atmosphere. Table III presents such results for the fire, for heats of combustion of 20 kJ/g and 40 kJ/g, a range typical of most fires. In order to carry out this calculation it is assumed that the smoke is distributed instantaneously throughout the volume being considered, one or four room-plenums. The barriers represented by walls or... 

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