Differential thermal analysis DTA

Differential thermal analysis (DTA) measures the temperature difference between a sample and a reference as the temperature is increased. A plot of the temperature difference (thermogram) reveals exothermic and endothermic reactions that may occur in the sample. The temperature for thermal events such as phase transitions, melting points, crystallization temperatures, and others can be determined 

At event 3, some water is formed between the crystals and cp rises. The of water is 

Solvent extraction is a useful separation technique especially for transition metal compounds. Ion exchange resins are similarly useful for separating cations or anions. 

When a solute is in equilibrium with two immiscible liquids, the ratio of its concentration in the two liquids is constant at constant temperature, provided the solutions are considered ideal. This ratio is the partition coefficient p. 

When an organic reagent, HR, reacts with a metal ion, M the following equilibria are established in aqueous solution  

In a mixture of water and an immiscible liquid, the species HR and MR are partitioned between water, w, and the organic solvent, o. The partition coefficients are  

This apparently depends on pH. Applying the law of mass action, it can be shown that  

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Thermal analysis iavolves techniques ia which a physical property of a material is measured agaiast temperature at the same time the material is exposed to a coatroUed temperature program. A wide range of thermal analysis techniques have been developed siace the commercial development of automated thermal equipment as Hsted ia Table 1. Of these the best known and most often used for polymers are thermogravimetry (tg), differential thermal analysis (dta), differential scanning calorimetry (dsc), and dynamic mechanical analysis (dma). 

The glass-tiansition tempeiatuiesfoi solution-polymeiized SBR as well as ESBR aie loutinely determined by nuclear magnetic resonance (nmr), differential thermal analysis (dta), or differential scanning calorimetry (dsc). 

Melting temperatures of as-polymerized powders are high, ie, 198—205°C as measured by differential thermal analysis (dta) or hot-stage microscopy (76). Two peaks are usually observed in dta curves a small lower temperature peak and the main melting peak. The small peak seems to be related to polymer crystallized by precipitation rather than during polymerization. 

Thermal Properties. The thermal stabiUty of cellulose esters is deterrnined by heating a known amount of ester in a test tube at a specific temperature a specified length of time, after which the sample is dissolved in a given amount of solvent and its intrinsic viscosity and solution color are deterrnined. Solution color is deterrnined spectroscopically and is compared to platinum—cobalt standards. Differential thermal analysis (dta) has also been reported as a method for determining the relative heat stabiUty of cellulose esters (127). 

Differential thermal analysis (DTA) Onset temperature of exotherms, heat of reaction, Cp, approximate kinetics... 

What are the consequences What is the maximum pressure Vapor pressure of solvent as a function of temperature Gas evolution Differential Thermal Analysis (DTA) / Differential Scanning Calorimetry (DSC) Dewar flask experiments... 

Reactivity (instability) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test Explosion propagation with detonation Drop weight test Thermal decomposition test Influence test Self-acceleration temperature Card gap test (under confinement) JANAE Critical diameter Pyrophoricity... 

The experiment duration is mueh longer than for differential thermal analysis (DTA) tests. 

Shock-modified zirconia powder was reacted with lead oxide in controlled differential thermal analysis (DTA) experiments and compared to the unmodified material by Hankey and co-workers [82H01]. This reaction yields... 

Fig. 7.10. The solid state reactivity of shock-modified zirconia with lead oxide as studied with differential thermal analysis (DTA) shows both a reduction in onset temperature and apparent increase in reaction rate. The shock-modified material has a behavior much like the much higher specific surface powder shown in B (after Hankey et al. [82H01]).

Thermogravimetric analysis has also been used in conjunction with other techniques, such as differential thermal analysis (DTA), gas chromatography, and mass spectrometry, for the study and characterisation of complex materials such as clays, soils and polymers.35... 

R.L. Bohon, AnalChem 35 (12), 1845-52 (1963) CA 60,1527 (1964) Approx heats of expin, Qv were detd on mg amounts of propints and expls by differential thermal analysis (DTA). Small-screw-cap metal cupsi sealed with a Cu washer served as constant vol sample containers the initial cup pressure could be controlled from 0 to approximately lOOOpsia. The calibration constant was calcd for each run from the total heat capacity of the cup and the relaxation curve, thereby compensating for equipment variations. 

The techniques referred to above (Sects. 1—3) may be operated for a sample heated in a constant temperature environment or under conditions of programmed temperature change. Very similar equipment can often be used differences normally reside in the temperature control of the reactant cell. Non-isothermal measurements of mass loss are termed thermogravimetry (TG), absorption or evolution of heat is differential scanning calorimetry (DSC), and measurement of the temperature difference between the sample and an inert reference substance is termed differential thermal analysis (DTA). These techniques can be used singly [33,76,174] or in combination and may include provision for EGA. Applications of non-isothermal measurements have ranged from the rapid qualitative estimation of reaction temperature to the quantitative determination of kinetic parameters [175—177]. The evaluation of kinetic parameters from non-isothermal data is dealt with in detail in Chap. 3.6. 

Reactivity (instabiiity) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test... 

Recently we investigated ferromagnetic properties of CoPt bimetallic nanoparticles [232,233]. CoPt3 nanoparticles can be prepared by a two-step reduction using NaBH4 as a reductant. The bimetallic nanoparticles were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), FT-IR, TEM) and XRD. Structural and spectroscopic studies showed that the bimetallic nanoparticles adopt an fee crystalline structure with an average particle size of 2.6 nm. SQUID studies revealed... 

In addition to these standardised test methods set by regulation (in particular the transport regulations of dangerous substances), there are laboratory methods that can provide more details regarding substance behaviour. In particular, there is differential thermal analysis (DTA), thermal gravimetric analysis, calorimetry and thermomanometry, which will not be described here. 

Phase diagrams give valuable information about the compounds that can form in a system of components. These compounds can then be prepared and studied. For the experimental determination of phase diagrams the following methods are used. In differential thermal analysis (DTA) a sample of a given composition is heated or cooled slowly... 

See entry differential thermal ANALYSIS(DTA) (reference 1) See other a-nitro... 

See entry differential thermal analysis (dta) See other oxosalts of nitrogenous bases... 

Differential Thermal Analysis (DTA). One of the characteristics of a rubber useful in tire rubber compounds is that it is amorphous at room temperature but readily undergoes strain induced crystallization. For this reason, copolymers were prepared in order to appropriately adjust the crystalline melt temperature. 

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