Specific gas profile

TG/FTIR Total Integrated (Absorption) Values of the Specific Gas Profiles in Nitrogen and Air Atmospheres... 

Decomposition of poly(ethylene terephthalate) as recorded using TG-DTA-FTIR. (A) Simultaneous TG-DTA curves. (B) IR absorption spectra of the evolved gases at various temperatures. (C) Specific gas profiles of the evolved gases. 

The TGA/FT-IR research focused on the characterization of cured amine activated epoxy systems. This hyphenated technique was used to quantitate activator-resin ration for the cured system for two different cure schedules. The "zap and "slow step" cures discussed in the experimental section are attractive processes for different reasons. The production line foreman would naturally prefer the "zap" cure since it would produce a high volume of parts in a short period of time. The polymer engineer favors the "slow step" cure since research has shown that this schedule produces the more thermodynamically stable product. The generated first derivative weight loss profiles and specific gas profiles were utilized to determine the cure schedule of these materials. 

Figure 3. The Specific Gas Profiles for "resin (1160 -1185 cm" ) and "activator (877 - 904 cm ) and the total Evolved Gas Profile generated during a TGA/FT-IR run of a "slow step cured epoxy sample. (Reproduced with permission fi om ref 6. Copyright 1993 Elsevier Science Publishers B.V.)...

The symmetric mode aims at combining the advantages of the simultaneous and the asymmetric mode only the endothermic reaction takes place in the main reactor. The process heat is added through a hot, inert side stream (e.g., the effluent gas of an external combustion chamber). The side stream can be distributed along the reactor in order to adjust a specific temperature profile. 

The main concern in proper reformer design and tube design is the supply of the same heat flux profile over each catalyst tube, ensuring that the heat flux supplied to the process gas inside the tube is in balance with the required reaction heat in that tube. This results in a specific temperature profile inside the tube from the inlet to outlet of the tube. This temperature profile is also reflected in the tube metal. 

Examination of specific ion profiles shows that the onset of the evolution of hydrogen chloride (loss of Cl ) occurs prior to the onset of the evolution of [HCy or [PhCHCl] suggesting that the latter ions may be products of secondary gas-phase reactions. Although the evolution profiles were broad, the average activation energy could be obtained by the measurement of the temperature maxima as a function of sample heating rates. The results of these studies are given in Table 9.11. 

The TGA/FT-IR study focused on the pyrolysis products of the cured system to measure activator/resin mtios and during the same run, compare generated "Activator" and "Resin" specific gas and first derivative weight loss profiles to... 

ATSDR. 1989. Decision guide for identifying substance-specific data needs related to toxicological profiles. Atlanta, GA Agency for Toxic Substances and Disease Registry, Division of Toxicology. 

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