Decomposition bags

The air bag industry has become one of the principal users of pyrotechnic compositions in the world. Most of the current air bag systems are based on the thermal decomposition of sodium azide, NaN, to rapidly generate a large volume of nitrogen gas, N2. Air bag systems must function immediately (within 50 ms) upon impact, and must quickly deploy a pulse of reasonably cool, nontoxic, unreactive gas to inflate the protective cushion for the driver or passenger. These formulations incorporate an oxidizer such as iron oxide to convert the atomic sodium that initially forms into sodium oxide, Na20. Equation 1 represents the reaction. 

Beryllium Nitrate. BeryUium nitrate tetrahydrate [13516-48-0], Be(N02)2 4H2O, is prepared by crystallization from a solution of beryUium hydroxide or beryllium oxide carbonate in a slight excess of dilute nitric acid. After dissolution is complete, the solution is poured into plastic bags and cooled to room temperature. The crystallization is started by seeding. Crystallization from more concentrated acids yields crystals with less water of hydration. On heating above 100°C, beryllium nitrate decomposes with simultaneous loss of water and oxides of nitrogen. Decomposition is complete above 250°C. 

The numerator of the first term is the number of ways N white balls could appear in 6 draws, and the denominator N is the number of ways these same Ar white balls could be interchanged. (Division by N in the first term reflects the fact that the order in which any specific white ball is drawn is unimportant, since this division by Nl produces the effect of making individual white balls indistinguishable.) If the decomposition of radioactive atoms and the resultant emission of charged particles really follow the laws of chance that govern the drawing of balls from a bag, then radioactivity must be a random process. 

FIGURE 4.18 The rapid decomposition of sodium azide, NaN3, results in the formation of a large volume of nitrogen gas. The reaction is triggered electrically in this air bag. 

Vehicle air bags protect passengers by allowing a chemical reaction to occur that generates gas rapidly. Such a reaction must be both spontaneous and explosively fast. A common reaction is the decomposition of sodium azide, NaN , to nitrogen gas and sodium metal. 

Tars have a tendency to cling to the filter surface and can undergo subsequent carbonization reactions that lead to fouling and plugging. Even in the absence of further decomposition, tars are difficult to remove from these materials. Examples of barrier filters suitable for biomass systems include rigid, porous-candle, or cross-flow filters constructed of metal or ceramic bag filters constructed of woven material, and packed-bed filters. 

IXacing cars, such as the one shown helow, can reach speeds that are well above 200 km/h. In contrast, the maximum speed of many farm tractors is only about 25 km/h. Just as some vehicles travel more quickly than others, some chemical reactions occur more quickly than others. For example, compare the two reactions that occur in vehicles the decomposition of sodium azide in an air bag and the rusting of iron in steel. 

Most gas calculations are just applications of the ideal gas law in which three of the variables P, V, T, and n are known, and the fourth variable must be calculated. For example, the reaction used in the deployment of automobile air bags is the high-temperature decomposition of sodium azide, NaN3, to produce N2 gas. (The sodium is then removed by a subsequent reaction.) How many liters of N2 at 1.15 atm and 30°C are produced by decomposition of 145 g of NaN3 ... 

Automobile air bags are inflated with N2 gas produced by decomposition of sodium azide. 

Polyethylene (PEI. In an unpublished study, pouches were made from paper/foil/PE laminates, and headspace gas was taken from the bag after incubation at 60° C for 20 minutes and analyzed by a gas chromatograph. Three major components were identified as acetaldehyde, allyl alcohol and acrolein. When odorous bags were compared with non-odorous bags, there showed a direct correlation between odor, acetaldehyde and allyl alcohol levels. Those compounds were considered to be thermal oxidative decomposition products of polyethylene (Baxter, J. A., W. Grayson and Assoc., Ltd., unpublished data). 

Table 17.1. Fungal and bacterial biomass associated with decomposing leaves in streams. All values are maximum biomass estimates from litter bag decomposition studies except the study by Findlay et al. (2002b) where average microbial biomass from randomly collected leaves was estimated...

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