Thermal stability tests

Thermal stability test by D3241 to meet 3.3 kPa (25 mm Hg) pressure drop and Code 3 Deposit Rating. 

Mercury (Quicksilver, Hydrargyrum), Hg, at wt 200.61, silvery liq, mp —38.87°, bp 356.9°, d 13.546g/cc at 20°. Insol in w, HC1, ale and eth sol In nitric acid. Sometimes found native poisonous. Can be prepd by heating the ore cinnabar (HgS) either in air or with lime. Forms numerous salts, some of which are very expl, eg, Hg fulminate, Hg azide, etc. The presence of Hg in expls, even in minute quants, is unde-sireable because it affects the result of thermal stability tests. Marshall (Ref 1) describes various tests used in Engl and Ger for its detection in different expls and propints Refs 1) Marshall 2, 708-12(1917) 2) Mellor... 

Use of thermal stability tests (DTA s) to determine the heat sensitivity of a given process mixture is desirable. Recent advances in analytical methods permit good calorimetric determination of heat of reaction. Heat of reaction data are critical for exothermic reactor vent sizing. Heat impact from fire is usually small in comparison, but should not be neglected. 

All theoretical calculations and tests performed in earlier stages, as well as the relevant literature, provide the inputs to the determination of the necessary detailed thermal stability testing for the substance, mixture, or reaction mass. 

Example 1 Typical Outputs of Thermal Stability Test Methods As discussed in detail later in Section 2.3, various techniques with different working principles are available to identify the thermal reactivity hazards of individual substances and reaction mixtures. Some examples are presented here. 

Fenlon, W. J., "A Comparision of ARC and Other Thermal Stability Test Methods," Pkant/Operations Progress, 3, No. 4,197 (1984). 

Fabrication of Polymer Film Samples for Thermal Stability Testing... 

N-halamines, 13 100-101 of ion-exchange resins, 14 401-402 of ionic liquids, 26 845-847 of olefin fibers, 11 229 of organic semiconductors, 22 209 of polyimides, 20 277 of silicones, 22 600 of Teflon AF, 18 340 Thermal stability tests, of organic peroxides, 18 491... 

A number of thermal stability tests arc available, some of which have developed into national (DIN) or international industrial standards (ISO). Pigments in thermoplastic systems, for instance, are studied under heat extrusion conditions [110]. The colorant to be tested, possibly together with titanium dioxide, is dispersed in the thermoplastic, using a mixer and a granulating extruder (Sec. 1.8.3). The pigmented test pellets are then fed into a screw extruder which ejects a standardized test specimen with defined dimensions [111]. Starting at the lowest possible temperature level, the extrusion temperature is increased by intervals of 10 or 20°C between samples. 

Thermal stability tests were carried out in inert and reducing atmospheres such as N2 and CO. In both cases the decomposition started at lower temperatures, at about 950 and 800 °C respectively, with formation of red-brown colored reaction products due to the presence of Cu20. 

In 55% of the cases, the accidents could have been foreseen by use of risk analysis, and in 35% of the cases by thermal stability testing. Different methods of stability testing were evaluated comparatively during the investigation of a runaway exothermic reaction which occurred during the preparation of a component mixture for a sealing composition in a 1200 1 reactor only DSC was effective in identifying the cause of the hazard. 

Several tests which are listed in Vol 1, p XV under Heat Tests (Thermal Stability Tests) are described in books of Reilly (1938) and Barnett (1919). These tests are not used in USA... 

As with drugs and purified biomarkers, thermal- and photostability of botanical products are the factors that must be considered. Commercial dried extract and capsules of SJW were evaluated under harmonized test conditions (25). Photostability testing showed all the constituents to be photosensitive in the tested conditions. However, different opacity agents and pigments influenced the stability of the constituents. Amber containers had little effect on the photostability of the investigated constituents. Long-term thermal stability testing showed a shelf life of less than four months for hyperforins and hypericins, even when ascorbic and citric acids were added to the formulation. 

---