Derivative differential thermal analysis

E.E. Mason, "Application of Derivative Differential Thermal Analysis to Military High Explosives . NAVWEPS Rept 6996... 

Derivative Differential Thermal Analysis. A technique yielding the first derivative of the differential thermal curve with respect to either time or temperature. 

DTA DDT A—Differential thermal analysis derivative differential thermal analysis. Test methods for pyrotechnic mixtures by gradual heating. 

Thermal properties of several chlorinated phenols and derivatives were studied by differential thermal analysis and mass spectrometry and in bulk reactions. Conditions which might facilitate the formation of stable dioxins were emphasized. No two chlorinated phenols behaved alike. For a given compound the decomposition temperature and rate as well as the product distribution varied considerably with reaction conditions. The phenols themselves seem to pyro-lyze under equilibrium conditions slowly above 250°C. For their alkali salts the onset of decomposition is sharp and around 350°C. The reaction itself is exothermic. Preliminary results indicate that heavy ions such as cupric ion may decrease the decomposition temperature. 

In order to obtain compounds with Ti-O-P and Zr-O-P units, the hexaethoxy-derivative, NsPaCOEOg, was treated with titanium and zirconium tetrachlorides. In each case, hygroscopic solids of the type NaPaCOEOiOaMCU (M = Ti or Zr) and ethyl chloride were obtained. The degree of polymerization of these solids was 1.6—1.8, and on the basis of their i.r. and n.m.r. spectra, two alternative structures, (46) and (47), were proposed. In an alternative route to the same type of compound, N3P3CI6 was treated with tetra-n-butoxytitanium in o-xylene. Butyl chloride was liberated and a solid was obtained which has been assigned the structure (48). Its thermal decomposition was studied by differential thermal analysis. 

TGA. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are other means to confirm the above structural models. Figure 4.4.8 shows the thermal analysis data for sample I. Curve (a) shows a TG datum of a mass loss about 22% after heating over 350°C. The derivative curve (b) of mass loss curve (a) clearly shows that there are at least four steps during the decomposition of the sample. This finding was further confirmed by the DTA data curve (c) shown in the same figure. It is clearly seen that there are four endothermic peaks. The DTA and TGA curves were similar for all samples. Note that the relative ratios of mass... 

Fig. 4.4.8 TGA and DTA result of sample 1. (a) Mass loss curve (b) Derivative curve of (a) (c) Differential thermal analysis curve. (From Ref. 10.)...

JOC 32(2), 285-9(1967) CA 70, 10960(1969) (Differential thermal analysis of nitramines. amine alts, and guanidine derivatives)... 

Differential thermal analysis of NGu s, amine salts, and Gu derivs) 23a) Poudreries R unies... 

Mos of the solid carbonaceous material available to industry is derived from the pyrolysis of petroleum residues, coal, and coal tar residues. Understanding the reactions occurring during pyrolysis would be beneficial in conducting materials research on the manufacture of carbonaceous products. The pyrolysis of aromatic hydrocarbons has been reported to involve condensation and polymerization reactions that produce complex carbonaceous materials (I). Interest in the mechanism of pyrolysis of aromatic compounds is evidenced in a recent study by Edstrom and Lewis (2) on the differential thermal analysis of 84 model aromatic hydrocarbons. The study demonstrated that carbon formation was related to the molecular size of the compound and to energetic factors that could be estimated from ionization potentials. 

For materials generally, change in expansion (or density) by dilatometry was traditionally the most often used method for measuring Tg. Thermal properties, for example specific heat, are also widely used, particularly the methods of differential thermal analysis". A method for rubbers using DSC is being developed in ISO TC 45 as ISO 22768, but is not yet published. The inflection point on the heat input - temperature curve is usually obtained automatically by the analyser s software but, if obtained manually, is best found from the derivative of the curve. 

Figure 9. Thermal analysis of levoglucosenone samples (a) neat, (b) +5% zinc chloride, (c) +5% diammonium phosphate, and (d) +5% diphenyl phosphate (D.t.a., differential thermal analysis T.g., thermo gravimetry D.t.g., derivative of thermogravimetry)...

On the basis of several analytical studies (differential thermal analysis, fluorescence, CPMAS solid-state NMR spectroscopy and others) [56-58] two models have been proposed to describe the structure of HCN-polymers, the Umemoto [59] and the Volker models [60]. In the Volker model, HCN polymerizes to extensive double-ladder rod-like structures, while a simpler mono-ladder pattern was hypothesized by Umemoto (Fig. 1). Irrespective of the structure assumed by HCN-polymers, a large panel of purine, imidazole and pyrimidine derivatives can be obtained by hydrolysis of these materials. In 1963, Lowe described the first example of acidic hydrolysis of the HCN-polymer (boiling 6.0 N HC1) to yield amino acids, carboxylic acids, adenine and hypoxanthine (Scheme 4). 

St CA 70, 10960(1969) (Differential thermal analysis of NGu s, amine salts, and Gu derivs) 23a) Poudreries Reunies de Belgique, SA, BelgP 717436(1968) CA 71, 51832(1969) (NGu recovery from triple-base expls crush under w to about 1 mm, extract the Nitroglycerol with methylene chloride extract the NGu from die residue with w) 24) J. 

Standard tests are utilized early in the evaluation phase to evaluate flammability, ignition and explosive characteristics. These include differential thermal analysis, thermo gravometric analysis, drop weight tests, friction tests, card gap (shock initiation) tests, and materials compatibility tests. Information derived from the above tests serve as a basis to establish safe procedures and techniques to handle and process the chemicals into propellants. 

Secondly, calorimetric measurements from the vapor phase may refer to nonequilibrium distributions of water vv ithin the crystals and through the zeolite bed. The very energetic vv ater-zeolite bond, especially for smaller water uptakes, means that water molecules may stick on sites vv here they first land. Subsequent redistribution can be very slow on the time scale of the experiment, particularly at the low temperatures employed 19, 21), 23° and 44°C. Finally, the information derived from differential thermal analysis is qualitative or at best only semiquantitative. 

Technical examination of objects coated with a protective covering derived from the sap of a shrubby tree produces information that can be used to determine the materials and methods of manufacture. This information sometimes indicates when and where the piece was made. This chapter is intended to present a brief review of the raw material urushi, and the history and study of its use. Analytical techniques have included atomic absorption spectroscopy, thin layer chromatography, differential thermal analysis, emission spectroscopy, x-ray radiography, and optical and scanning electron microscopy these methods and results are reviewed. In addition, new methods are reported, including the use of energy dispensive x-ray fluorescence, scanning photoacoustical microscopy, laser microprobe and nondestructive IR spectrophotometry. 

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