Inert atmospheres impacts

Although the related unsolvated Na2[Cr(CO)5] (4) does not normally explode or decompose at room temperature under an inert atmosphere, we have observed that a finely divided black powder, similar in appearance to the aforementioned one, rapidly formed when small amounts of air were inadvertently introduced into an evacuated flask of unsolvated Na2[Cr(CO)5], Under these conditions, the latter violently exploded, due to thermolysis of the pyrophoric product. Interestingly, unsolvated Na-[(C5H5)Ti(CO)4.] has also been observed to easily explode at room temperature on mild impact under an argon atmosphere. Thus, unsolvated alkali metal salts of all early transition metal carbonyl anions must be regarded as potentially explosive or shock-sensitive substances and manipulated carefully and handled with considerable care and respect. 

We should emphasize that the Li surface chemistry may be strongly influenced by reactive contaminants in the ppm level. In this section, we mention the impact of a few important and commonly abundant impurities. These include the atmospheric components 02, N2, C02, and H20 (unavoidably present in all nonaque-ous solutions and in any inert atmosphere, even of the highest quality), HF (which... 

It should be noted that the conditions of performance also dictate selection of required protection. For example, many pipes are buried underground and these only require proteetion for an expected time and conditions of their storage under most extreme conditions. The other example is an atmosphere under which a product performs. Figure 3.22 shows that PVC containing titanium dioxide degrades much slower under an inert atmosphere (nitrogen) than in the presence of air. If, then, air is restricted for any reason, this also impacts the required protection level. 

PROPERTIES OF SPECIAL INTEREST Kapton films have excellent thermal stability in air or inert atmosphere, useful mechanical properties over very broad temperature range, outstanding electrical properties and stability of these electrical properties over wide range of relative humidity, insensitive to solvents, excellent radiation resistance considerable variation in hydrolytic sensitivity, poor hydrol5dic resistance in 10% NaOH. Vespel direct-formed parts are resistant to thermally harsh environment, creep, impact, and wear, and friction at high pressures and velocities. ... 

There is a very large literature on the effects of ultraviolet radiation, typically at 254 nm, on polymers in inert atmospheres or vacuiun (see eg Refs. 110 and 111). Most of this is irrelevant to poisoners in normal use, although there are a few exceptions, for example the use of polycarbonate as impact-resistant lenses for mercury-vapor lamps in street lighting. 

A detailed elucidation of dehydrochlorination rates of PVC blends with high-impact PS (HIPS) containing 16% non-grafted PS, poly(styrene-co-acrylonitrile) (SAN) and acrylonitrile-butadiene-styrene terpolymer (ABS) containing 27% non-grafted SAN in an inert atmosphere at 180 "C revealed accelerated degradation of the PVC component. The increased content of acrylonitrile in SAN enhances PVC dehydrochlorination. The improved miscibility of thermally treated PVC/SAN blends was related to the formation... 

This work shows the application of quantitative pyrolysis-gas chromatography coupled with infrared spectroscopy and electron impact mass spectrometry in the study of radiation-induced scission of bisphenol-A polycarbonate (PC). PC under vacuum was gamma-irradiated using a 60Co source in the dose range from 0.125 to 1.0 MGy. This was followed by flash pyrolysis under an inert atmosphere observed by GC-FTIR-MS. Pyrolysis of the irradiated PC gave different products depending on the dose. Yields of carbon dioxide and methane decreased with dose whereas those of phenol and 4-methylphenol increased. The yields of benzene and toluene were unaffected by irradiation. Analysis of the products in this study helped to infer two main pathways for the radiation-induced scission of PC that involve carbonate bond rupture or aliphatic-aromatic bond rupture. 30 refs. 

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