Explosions differential scanning calorimetry

In 1969 a serious explosion took place in Basle when 287 kg (1.3 kmol) of 2-chloro-4,6-dinitroaniline was diazotized in 384 kg 40% nitrosylsulfuric acid. The temperature was increased from 30 °C to 50 °C and kept at that level. Shortly afterwards the explosion occurred three workers were killed and 31 injured, some seriously. The reaction had been carried out twice before in the same way without difficulty. Detailed investigations (Bersier et al., 1971) with the help of differential scanning calorimetry showed that, at the high concentration of that batch, a strongly exothermic reaction (1500 kJ/kg) starts at about 77 °C. In contrast, when the reactants were diluted with 96% sulfuric acid to twice the volume, the reaction was found to begin at 146 °C, generating only 200 kJ/kg. 

A more detailed investigation of the thermal behavior of the exploding [ ]rotanes by differential scanning calorimetry (DSC) measurements performed in aluminum crucibles with a perforated lid under an argon atmosphere revealed that slow decomposition of exp-[5]rotane 165 has already started at 90 °C and an explosive quantitative decomposition sets on at 150 °C with a release of energy to the extent of AH(jecomp = 208 kcal/mol. Exp-[6]rotane 166 decomposes from 100°C upwards with a maximum rate at 154°C and an energy release of AH(jg on,p=478 kcal/mol. The difference between the onset (115°C) and the maximum-rate decomposition temperature (125-136°C) in the case of exp-[8]rotane 168 is less pronounced, and AHjecomp 358 kcal/mol. The methy-... 

The worst hazard scenarios (excessive temperature and pressure rise accompanied by emission of toxic substances) must be worked out based upon calorimetric measurements (e.g. means to reduce hazards by using the inherent safety concept or Differential Scanning Calorimetry, DSC) and protection measures must be considered. If handling hazardous materials is considered too risky, procedures for generation of the hazardous reactants in situ in the reactor might be developed. Micro-reactor technology could also be an option. Completeness of the data on flammability, explosivity, (auto)ignition, static electricity, safe levels of exposure, environmental protection, transportation, etc. must be checked. Incompatibility of materials to be treated in a plant must be determined. 

Differential scanning calorimetry (DSC) and dust explosion tests are usually conducted before a new chemical goes into the pilot-plant phase. 

The research papers which originated in the last couple of years in different countries in this field indicate that ED and Er are not generally reported and there is an emphasis on the study of comprehensive thermal behavior of explosives as a function of temperature or time by means of different thermal analytical techniques. Most commonly used methods of thermal analysis are differential thermal analysis (DTA), thermogravimetric analysis (TGA) or thermogravimetry and differential scanning calorimetry (DSC). 

The common methods of investigating the kinetics of explosive reactions are differential thermal analysis, thermogravimetric analysis and differential scanning calorimetry. 

DIFFERENTIAL SCANNING CALORIMETRY METHODS IN THE DETERMINATION OF THERMAL PROPERTIES OF EXPLOSIVES. 

The energy yield of porous silicon explosive devices was measured using a calorimetric bomb test, resulting in a value of 7.3 kJ/g with calcium perchlorate as oxidizer (Clement et al. 2005). Differential scanning calorimetry techniques were also used to measure the energy output for sodium perchlorate at almost 9 kJ/g (Plummer et al. 2008). The extent of the NaC104 reaction was observed with bomb calorimetry in N2 and O2 atmospheres. Without the supplementary O2 environment, the heat of reaction was measured to be 9.9 1.8 kJ/g, but with supplementary O2, the reaction yielded 27.3 3.2 kJ/g and approached the theoretical value of 33.0 kJ/g for complete Si oxidation (Becker et al. 2010). 

Kishore, K. (1977) "Thermal decomposition studies on Hexahydro-1,3,5-trinitro-s-triazine (RDX) by differential scanning calorimetry", Propellants and Explosives 2, 78-81. 

Whelan, D.J., Spear, R.J., Read, R.W. The thermal decomposition of some primary explosives as studied by differential scanning calorimetry. Thtamochim. Acta 80, 149-163 (1984)... 

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