Volatile production, temperature dependence

The first approach is the most appealing, but the evolution of a volatile product is dependent not only on the temperature and rate of temperature change, but also on the type and nature of the furnace atmosphere. The second method was used by Stewart (12) in his temperature calibration scheme but required that the thermocouple be in contact with the sample or the sample container during the calibration procedure. Compounds chosen for standards were those containing solid, soiid2 or solid liquid... 

The reaction of volatile chlorinated hydrocarbons with hydroxyl radicals is temperature dependent and thus varies with the seasons, although such variation in the atmospheric concentration of trichloroethylene may be minimal because of its brief residence time (EPA 1985c). The degradation products of this reaction include phosgene, dichloroacetyl chloride, and formyl chloride (Atkinson 1985 Gay et al. 1976 Kirchner et al. 1990). Reaction of trichloroethylene with ozone in the atmosphere is too slow to be an effective agent in trichloroethylene removal (Atkinson and Carter 1984). 

All of the injections were 1 microliter and the capillary column split ratio was nominally set at 200 1. Column and program times and temperatures were varied depending on the volatile products being analyzed. 

The dependence of the volatile product yield with structure can be a very sensitive probe of radiation resistance and the protective effect of aromatic rings. G(H ) was observed to decrease from 5.6 to 0.038 for cyclohexane (3) and benzene (A) after gamma irradiation at ambient temperature. Since all polymers under investigation contained the sulfone moiety, G(SO ) (Table III) is an ideal probe for radiation resistance for this series. 

PBS (Figure 30) is an alternating copolymer of sulfur dioxide and 1-butene. It undergoes efficient main chain scission upon exposure to electron beam radiation to produce, as major scission products, sulfur dioxide and the olefin monomer. Exposure results first in scission of the main chain carbon-sulfur bond, followed by depolymerization of the radical (and cationic) fragments to an extent that is temperature dependent and results in evolution of the volatile monomers species. The mechanism of the radiochemical degradation of polyolefin sulfones has been the subject of detailed studies by O Donnell et. al. (.41). 

The term volatile matter content (of coal) is actually a misnomer, insofar as the majority of the volatile matter is the volatile product of the thermal decomposition of coal through the application of high temperatures. The extent to which the more volatile smaller molecules of coal (Vahrman, 1970) add to this is dependent on the coal and should be determined by nondestructive methods such as extraction by solvent(s). Relative yields and boiling-point profiles provide the extent to which natural molecules contribute to the volatile matter without any influence from high-temperature cracking. 

Figure 4. The set of thermograms of BSA in condensed state showing the temperature dependence of the mass spectra for volatile products of protein decomposition at m/z 17 (OH ), 28 (CO+), 34 (H2S),and44(C02).

Chromatograms obtained while heating the three PE-catalyst samples show catalyst-dependent differences in volatile product distributions. Figure 2.3 shows the gas chromatograms obtained at the temperatures corresponding to the maximum volatile product evolution rates for each PE-catalyst sample. Figure 2.3 clearly shows that relative hydrocarbon product yields depended on which catalyst was employed. For the PE-HZSM-5 sample, many isomeric hydrocarbons were detected, most of which were low molecular weight substances with short retention times. Volatile product diversity is less evident... 

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