Differential scanning calorimetry thermal decomposition

Thermal analysis using differential scanning calorimetry (dsc), thermogravimetric analysis (tga), and differential thermal analysis (dta) can provide useful information about organic burnout, dehydration, and decomposition. 

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-... 

In another study, thermodiffractometry was used to study phase transformations in mannitol and paracetamol, as well as the desolvation of lactose monohydrate and the dioxane solvatomorph of paracetamol [56]. The authors noted that in order to obtain the best data, the heating cycle must be sufficiently slow to permit the thermally induced reactions to reach completion. At the same time, the use of overly long cycle times can yield sample decomposition. In addition, the sample conditions are bound to differ relative to the conditions used for a differential scanning calorimetry analysis, so one should expect some differences in thermal profiles when comparing data from analogous studies. 

These tests include differential scanning calorimetry (DSC) and various forms of differential thermal analysis (DTA) the insulated exotherm test (IET), decomposition pressure test (DPT), and the Carius (or ICI) sealed tube test. Commercial variants of these tests are available. 

When conducting a differential scanning calorimetry (DSC) study on the stability of carbonaceous anodes in electrolytes, Tarascon and co-workers found that, before the major reaction between lithiated carbon and fluorinated polymers in the cell, there was a transition of smaller thermal effect at 120 °C, marked peak (a) in Figure 28. They ascribed this process to the decomposition of SEI into Li2C03, based on the previous understanding about the SEI chemical composition and the thermal stability of lithium alkyl carbonates.Interestingly, those authors noticed that the above transition would disappear if the carbonaceous anode was rinsed in DMC before DSC was performed, while the other major processes remained (Figure 28). Thus,... 

As described in Section 3.3.2.1 on heat sensitivity, thermoanalytical methods are sufficiently sensitive as an early indication of incipient chemical decomposition or chemical reaction, that is, stability and incompatibility. Some research papers discuss the use of differential thermal analysis (DTA) and differential scanning calorimetry (DSC) for this purpose [20-22]. 

Next, the thermal properties of the dye must be such that absorption of the laser energy will result in dye diffusion but not in decomposition. The melting temperature Tm, the latent heat of fusion, AH, and the specific heat for these dyes were determined by differential scanning calorimetry using a DuPont 990 Thermal Analyzer. The data are given in Table II. No thermal decomposition products for these dyes were detected upon heating to 600 °C for 20 msec. 

G. Krien, Thermal Decomposition of Tetrazene , SympChemProblConnectedStab-Expls (Proc) 1976, A, 371-76 (1977) CA 87, 203825 (1977) [The author reports a differential scanning calorimetry study on the decompn kinetics of Tetrazene. It was found that no simple set of kinetic eqtns can describe the thermal decompn of the compd. He concludes that the reason for the stability of Tetrazene at RT. in contrast to its instability at elevated temps, is its very high activation energy]... 

A range of heterocyclic azides were studied by differential scanning calorimetry, the enthalpies of thermal decomposition were lower than might have been expected, from 0.3—1 kJ/g. If ortho substituents onto which the azide could cyclise were present, decomposition enthalpies were, as one would expect, lower still [5], as well as the individually indexed compounds ... 

Chromophores must be thermally robust enough to withstand temperatures encountered in electric field poling and subsequent processing of chromophore/polymer materials. Chromophore decomposition temperatures can be assessed by techniques such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA and DSC measurements on neat chromophore samples in air will tend to yield decomposition temperatures lower than those for the same chromophores in hardened polymer lattices. Typically, to be useful for development of device quality materials, a chromophore must exhibit thermal stability of 250 °C or higher (with thermal stability defined as... 

Recently, two pyrazine (pz)-linked hetero-triads of cobalt phthalocyanine (CoPc) and ZnTPP, namely (CoPc)-pz-(ZnTPP)-pz-(CoPc) (15) and (ZnTPP)-pz-(CoPc)-pz-(ZnTPP) (16), have been prepared [30], The thermal properties of these triads and related macrocyclic components have been studied by thermal gravimetric analysis and differential scanning calorimetry. It has been found that the thermal stability of axial coordination increases in the order ZnPc(pz)2 < ZnTPP(pz)2 sa CoPc(pz)2, and the thermal decomposition of the triads 15 and 16 proceeds firstly via the degradation of the spacer ligand. 

The differential scanning calorimetry (DSC) thermograms for a-, (3- and -cyclo-dextrins are identical. Two heat absorption peaks are present the first occurs at 100°C as water is evaporated from the crystals the second, occurring at 250°C, is a result of crystal melting and thermal decomposition. 

The thermal behavior of TKX-50 (bis(hydroxylammonium) 5,5 -(tetrazolate-liV-oxide)) and the kinetics of its thermal decomposition were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermal decomposition of TKX-50 starts to occur within the range 210-250 °C depending on the heating rate used. 

It is well known that most of the diazoniun compounds are thermally unstable and easily decompose in an aqueous solution. Iherefore, the thermal stability of diazoniun salts in an aqueous solution and in a film was evaluated by a kinetic analysis of the thermal decomposition and differential scanning calorimetry (DSC) analysis. 

A recent study on the stability of various indium alkyl derivatives has been performed using differential scanning calorimetry (DSC), which provides a comprehensive thermal fingerprint of the compounds. In addition, when this method of thermal analyses is used in conjunction with thermogravimetric analysis coupled to FTIR and/or GCMS evolved gas analysis, it can provide a complete mechanism for the decomposition pathway of prospective compounds. ... 

In contrast to polymerisates, polycondensates can not be depolymerized under inert conditions. Decomposition usually leads to the destruction of the chemical structure and the monomers. The thermal decomposition of PET starts at about 300°C in an inert atmosphere [25]. Between 320 and 380°C the main products are acetaldehyde, terephthalic acid, and carbon oxides under liquefaction conditions. The amounts of benzene, benzoic acid, acetophenone, C1-C4 hydrocarbons, and carbon oxides increase with the temperature. This led to the conclusion that a P-CH hydrogen transfer takes place as shown in Eigure 25.8 [26]. Today the P-CH-hydrogen transfer is replaced as a main reaction in PET degradation by several analytic methods to be described in the following sections. The most important are thermogravimetry (TG) and differential scanning calorimetry (DSC) coupled with mass spectroscopy and infrared spectroscopy. 

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