Volatile thermal decomposition products

J. Bozi, Z. Czeg ny, and M. Blazs6, Conversion of the volatile thermal decomposition products of polyamide-6,6 and ABS over Y zeolites, Thermochim. Acta, 472(l-2) 84-94, June 2008. 

Frankel, E.N. and Gardner, H.W. 1989. Effect of a-tocopherol on the volatile thermal decomposition products of methyl linoleate hydroperoxides. Lipids 24 603-608. 

ONYEWUETAL. Volatile Thermal Decomposition Products of f -Carotene 249... 

Frankel, E.N., Neff, W.E., Selke, E. and Weisleder, D. Photosensitized oxidation of methyl linoleate. Secondary and volatile thermal decomposition products. Lipids 17, 11-18 (1982). 

Energetics. In principle, the heat (enthalpy) of gasification is the difference between the enthalpy of the solid in the initial state at ambient temperature and pressure, To, Po, and the enthalpy of the volatile thermal decomposition products at Tp, Pq. If the stored heat is Ahs, the enthalpy of fusion (melting) for semicrystalline polymers is Ahf, the bond dissociation enthalpy is Ahd, and the enthalpy of vaporization of the decomposition products is Ah, then the enthalpy of gasification per imit mass of fuel is (10)... 

This type of preliminary examination will rapidly reveal the formation of certain volatile thermal decomposition products of solid test materials. When liquid samples are being tested, a portion should be taken to dryness on a water bath, keeping in mind, of course, any possible volatilization or decomposition of certain essential materials. 

In analogy to Luyk et al [674], also Blazso [888] has been driven by environmental concerns in a PyGC-MS and in-source TPPy-MS study to identify the nature and to monitor the evolution of chlorine-containing volatile thermal decomposition products from three organic pigments dispersed in synthetic... 

An example of the effect of source temperature is seen for TiF40xH 110), for which, at 180°C, the highest m/e corresponds to TiFsOX (i.e., P—HF), whereas at 240°C the thermal decomposition product, TiF20X2, is observed. Compound Cu(NOs)2 shows a parent ion 111, 112) [unlike Sn(NOs)4 (79)], but thermal decomposition occurs even at source temperatures of 100°C resulting in much of the N02 and NO observed. As samples are volatilized from the probe at temperatures of up to 350°C, serious thermal decomposition or polymerization may result 8,113-116). Even with the source at a low temperature, there is still the very hot region in the vicinity of the filament that can cause pyrolysis. 

Mass spectrometry should be used discriminately where a maximum amount of information can be expected. The heavier nonvolatile feedstocks are for practical purposes, beyond the useful range of routine mass spectrometry. At the elevated temperatures necessary to encourage volatility, thermal decomposition will occur in the inlet and any subsequent analysis would be biased to the low molecular weight end and to the lower molecular products produced by the thermal decomposition. 

When a fat or oil is heated, thermal instability may cause decomposition, and depending on the temperature reached, subsequent combustion of volatile gaseous decomposition products (Mehlenbacher, 1960). The thermal stability of fats and oils is thus essentially a chemical characteristic. However, stability is characterized by measuring certain critical temperatures, the smoke, flash and fire points, at which certain heat-induced changes become apparent. It is appropriate, therefore, to include here methods for measuring these critical points. 

Since the thermal decomposition products of QF AsF are all volatile whereas the CioFgAsF is thermally stable and involatile at room temperature, a quantitative conversion of CjoFg to the salt can be achieved. This has settled the composition as C o FgAsF. It is not, however, necessary to employ QFgAsFg as the oxidizer. A convenient, clean synthesis uses a mixture of ASF3 and F2 in SO2CIF. 

Many investigations have been carried out of gas chromatography of tobacco alkaloids in order to study the volatile compounds of the smoke, i.e. thermal decomposition products of alkaloids and other substances in tobacco. This chapter is mainly concerned with the gas chromatography of the alkaloids themselves and their metabolites in man, also to some extent with the decomposition products of the alkaloids. 

Once heating of the source begins there are additional sources of background gas including desorption of gases from the source, crucible (if one is used), filaments, and other surfaces in the vacuum chamber through radiative or conductive heating volatile materials incorporated in the source material and thermal decomposition products. 

Liquids burn in the vapour phase, so that a liquid has to evaporate in order to form a combustible vapour layer above the surface of the liquid. A liquid is thermally stable when its molecules in the volatilized vapour phase are identical to those in the liquid phase. Most combustible liquids are thermally unstable i. e. their chemical constitution is changed by heating. In the vapour phase, therefore, molecules of the original liquid are accompanied by their thermal decomposition products as well as by their oxidized derivatives. This complex vapour mixture is mixed with air, resulting in a combustible composition within certain concentration limits just as for gases as described above. 

Klimisch, H. J. Generation of constant concentration of thermal decomposition products in inhalation chambers. A comparative study with a method according to DIN 53 436. II. Measurement of concentrations of total volatile organic substances in inhalation chambers. J. Combustion Toxicology, 7, No. 11, 257 (1980)... 

As observed with the monohydroperoxides (Section D), thermal decomposition of the hydroperoxy bicyclo-endoperoxides from methyl linolenate produced more complex mixtures of volatile compounds than acid decomposition with acidic methanol. The thermal decomposition products included methyl 9-oxononanoate, propanal, 2,4-heptadienal, methyl octanoate, methyl 13-0X0-9,11-tridecadienoate and ethane (Figure 4.25X The acid decomposition products, analysed as the di- and tetramethyl acetals, comprised only propanal, methyl 9-oxononaoate, and malonaldehyde. As with the monohydroperoxides, by thermal decomposition the bicyclo-endoperoxides are cleaved on either side of the hydroperoxide group, whereas by acid decomposition they are cleaved only between the hydroperoxide group and the... 

Normally, the analyses mentioned previously are performed on the residual materials. However, there is nothing to prevent measurements being made on the separated fractions or on condensate materials. In the case of samples containing water, be aware that the condensate will be enriched with water. An interesting approach to the controlled evaporation of materials is to use the combined techniques of thermogravimetric analysis and infrared. Although this technique is typically used for the determination of thermal decomposition products, it may also be used for controlled and reproducible selective removal of volatile components, with on-line monitoring of the volatile components. 

---