Thermal decomposition index

Polytetrafluoroethylene decomposition products thermal decomposition of the fluorocarbon chain in air leads to the formation of oxidized products containing carbon, fluorine and oxygen. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentration should be minimal. (Trade names Algoflon, Fluon, Teflon, Tetran.)... 

Aromatic acyl halides containing a nitro group adjacent to the halide function show a tendency towards violent thermal decomposition. The few individually indexed compounds are ... 

GLC-retention index (ly) data (137,138). Thermal decomposition data (139,151). 

IR spectra measurements as well as variation of the film thickness, shrinkage, and refractive index demonstrated substantial differences in the mechanisms of thermal decomposition of films prepared from the exclusively metal alkoxide precursor and from the metal alkoxides modified by 2-ethylhexanoic acid. These differences affect the evolution of film microstructure and thus determine the different dielectric properties of the obtained films. The dielectric permittivity of the films prepared from metal alkoxide solutions was relatively low (about 100) and showed weak dependence ofthe bias field. This fact may be explained by the early formation of metal-oxide network (mostly in the... 

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 ... 

A few moments thought about the nature of the surface of an oxide leads to the conclusion that the surface oxide ion should have quite different properties than the bulk lattice ions. For example, consider a simple cubic oxide such as MO with a sodium chloride structure where each ion is sixfold coordinated if this is cleaved along a <100) plane, then the coordination of the ions in this plane is reduced from six- to fivefold. This new surface will not be ideal, and ions of still lower coordination will also be present where higher index planes are exposed at the surface. However, for MgO prepared by thermal decomposition of the hydroxide or carbonate, evidence from electron microscopy (130) indicates that these have high index planes that... 

The title compound was prepared by thermal decomposition of the monoclinic dihydrate FeP04-2H20. The solid-state preparation reaction is likely responsible for the poor crystallinity, and therefore, peak broadening. The inadequate crystallinity of the material results in the insufficient accuracy of both the peak positions and intensities. A serious lack of resolution in this particular powder diffraction pattern, which occurs due to the physical state of the powder, translates into considerable problems in both the indexing and structure determination. When experimental data collected using Cu Ka radiation were employed in the ab initio indexing, ITO and TREOR runs did not result in a reasonable solution. 

Note The term crystolysis reaction was proposed for use in describing the thermal decomposition of a solid reactant (31,72). This specific label is of value as a keyword and index entry, while also confirming that the reaction of interest proceeded in the crystalline state. This important aspect of behavior is not always explicitly stated in reports of many thermal investigations, where the phase in which the change occurs is not positively identified. 

Table 16.2. Molar thermal decomposition function Yd y2 calculated by group contributions, the quantity (NYd - NH) entering the correlation equation, and the fitted or predicted (fit/pre) values of Yd y2, f°r 180 polymers. NYd is a correction index. NH is the number of hydrogen atoms in the repeat unit. For 40 of these polymers, Yd l/2(group) cannot be calculated because of the lack of some of the group contributions, but Yd l/2(fit/pre) can be calculated by using the... 

Optical Crystallographic Properties. As prepared by the thermal decomposition of ammonium hexafluorovanadate-(III), vanadium(III) fluoride has too fine a crystal size for the determination of optical properties with a polarizing microscope. Heating to 1350° in a platinum tube forms twinned crystals that are easily studied. According to Weaver, these crystals are biaxial (y=-) with optic angle (2V) of 5 to 10°. The a- and y-refractive indexes are, respectively, 1.536 and 1.544. 

Calculate, from data in handbooks, the TG curve for the thermal decomposition of 100 mg of urea (see Merck Index). Assume all processes are quantitative. 

Thermal decomposition of the concentrate and compound samples was carried out using a Ray-Ran benchtop injection molding machine. This unit resembles an oversize melt index plastometer and is equipped with a heated barrel, die and plunger assembly. The capacity of the barrel is approximately 20 g. 

Sample Test Data. Thirty different NLO chromophores were tested to provide a thermal stability index. Of these, seven were studied using both melting endotherm and decomposition exotherm disappearance whereas the other twenty-three compounds were studi using only the decomposition exotherm decreases. makes a total of thirty-seven samples whose data are given in Table m. The chemical structures corresponding to the sample names are shown in Figures 5,6 and 7. 

Material-invariance of the relative drop in oxygen index with increasing temperature is explained by the fact that the diffusion-controlled intermixing with oxygen is the determinant process rather than the thermal decomposition which follows the Arrhenius law. Diffusion processes are known to fit to a plot against the 3/2 power of temperature. 

It should be noted here that all the above flammability characteristics, such as thermal decomposition, ignition, and heat generation are practically invariant with respect to the form of the test material, i.e. powders, granules, sheets, films can all be equally used. Although the oxygen index determination requires standardized specimens, the results are slightly dependent on the dimensions of the specimen within certain limits. 

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