Thermal stability differential

Figure 7.2 Thermal stability (differential scanning calorimetry) of polystyrene-based solid support (Merrifield resin) (A. Stadler and C.O. Kappe, unpublished results).

Thermal stability Differential scanning calorimetry (DSC) Coir, bagasse 45,55... 

TATB has excellent thermal stability. Differential Scanning Calorimeter measurements show exotherms at 330°C and 350°C when run at a heating rate of 10°C per minute. In the 1000 heat test, approximately. 17 cubic centimeters of gas are evolved in 48 hours. In the 200°C test for 48 hours 0.5 cubic centimeters of gas are evolved at 220°C for 48 hours 2.3 cubic centimeters are evolved. At 260°C for one hour approximately 1.2 cubic centimeters of gas are evolved. At 280°C 2.0 cubic centimeters of gas are evolved. Figure 8-53 shows the DTA curve for TATB. 

Assessing the Thermal Stability of Chemicals by Methods of Differential Thermal Analysis, American Society for Testing and Materials, Philadelphia. 

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 thermal stability of peroxides can be expressed in terms of their half-hfe (ti/a)- Half-life values can be estimated in solution utilizing the technique of differential thermal analysis. These values, or more precisely the temperatures at which their half-life is equivalent, provide an indication of practical vulcanization temperatures [49] (Table 14.29). 

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

From the discussion presented of reactions in solids, it should be apparent that it is not practical in most cases to determine the concentration of some species during a kinetic study. In fact, it may be necessary to perform the analysis in a continuous way as the sample reacts with no separation necessary or even possible. Experimental methods that allow measurement of the progress of the reaction, especially as the temperature is increased, are particularly valuable. Two such techniques are thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). These techniques have become widely used to characterize solids, determine thermal stability, study phase changes, and so forth. Because they are so versatile in studies on solids, these techniques will be described briefly. 

Three flame retardants were compared in this study, namely, a brominated polycarbonate oligomer (58% bromine), a brominated polystyrene (68% bromine), and a brominated triaryl phosphate ester (60% bromine plus 4% phosphorus). These are described in Table I. Figures 1 and 2 compare the thermal stability of the brominated phosphate with commercial bromine-containing flame retardants by thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). The brominated phosphate melts at 110°C and shows a 1% weight loss at 300°C. Brominated polycarbonate and brominated polystyrene are polymeric and are not as volatile at elevated temperatures as the monomeric flame retardants. 

A DuPont 910 differential scanning calorimeter (DSC) and a DuPont 951 thermogravimetric analyzer (TGA) connected to a DuPont 1090 thermal analyzer 3ftre used to study the transition data, thermal stability, and char yield, respectively, for all the polymers. The DSC was run under a nitrogen stream at a flow rate of 80 c.c./min. and at a heating rate of 20°C/min.. 

Differential thermal analysis ("DTA") is a measuring method which makes it possible to study the heat transfer during physical and chemical reactions. This can be done with small samples (usually a few milligrams). This analysis is suited for studying the thermal stability of materials and can in many cases be used to assess the thermal potential of chemical reactions. 

JH NMR) studies confirmed the presence of the AB diblocks in the product. This determination was facilitated by the fact that the dendritic nitroxide could be differentiated from the nonnitroxide-bearing dendron by NMR spectroscopy. Careful analytical studies confirmed that the pure ABA copolymers could be separated by column chromatography and that the undesired diblock impurity resulted mainly from the loss of the dendritic nitroxide during the course of the reaction. Obviously, this approach to ABA triblocks has rather limited practical value since the thermal stability of the final product is quite low. 

We have synthesized two small scale batches (PA-DBX 1 and 2) of 2-3 g each and one intermediate scale batch (PA-DBX 3) of 8-10 g of DBX-1 from our NaNT. The procedure used to synthesize DBX-1 was based on literature methods.[5,6] For each batch, sensitivity tests, thermal stability by differential scanning calorimetry (DSC), and performance tests were performed and compared to the standard DBX-1 that was obtained from PSEMC (Pacific Scientific Energetic Materials Company, inventors of DBX-1). 

The typical differential scanning colorimetric (DSC) traces shown in Figure 9.2 compare the thermal transitions of similar low-DEG-content PEN and PET resins. The fact that the glass transition temperature (Tg) of PEN is 45-50 °C higher than that of PET has a major influence on the processing and performance of PEN applications. In addition, the fact that PEN S Tg is 20-25 °C above the boiling point of water has a significant effect on the thermal stability potential of many hot, aqueous exposure applications. 

On the basis of an IR study of some s-triazines and HA systems, several authors reported that ionic bonding took place between a protonated secondary amino group of the s-triazine and a carboxylate anion on the HA [17,146,147]. Successive studies, mainly conducted by IR spectroscopy, confirmed previous results and also provided evidence for the possible involvement of the acidic phenol-OH of HA in the proton exchange of the s-triazine molecule [17, 146-150]. Differential thermal analysis (DTA) curves measured by Senesi and Testini [146, 147] showed an increased thermal stability of the HA-s-triazine complexes, thus confirming that ionic binding took place between the interacting products. 

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,... 

Flandin F, Buffevant C and Herbage D (1984) A differential scanning calorimetry analysis of the age-related changes in the thermal stability of rat skin collagen. Biochim Biophys Acta 791, 205-211. 

In industrial practice temperature stability of a polymer means that it is able to maintain its mechanical properties up to a certain temperature and over a certain time period. Depending on the environmental conditions under which the thermal stability is measured one ftuther differentiates between two cases physical thermostability if the thermal treatment occurs in inert atmosphere and chemical thermostability if the thermal treatment is done, e.g., in the presence of air (thermooxidative stability). 

Microwave spectroscopy indicates that aromaticity diminishes in the order 1,2,5-thia-diazole > thiophene > l,3,4-thiadiazole> l,2,5-oxadiazole> 1,2,4-oxadiazole <84CHEC-1(4)545, B-85MI 410-01>. The aromaticity of heterocycles has been discussed by Katritzky and Barczynski (90JPR885) and by Bird <94H(37)249>. The thermal stability of 2,5-substituted thiadiazoles (23) was studied by differential scanning calorimetry and shown to increase as the rt-contribution of the substituents becomes greater <89MI410-01>. 

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