Chemical Stability and Compatibility

A large number of dinitramide salts have been reported in the literature. They are formed with metallic cations or with protonated organic nitrogen bases. 

Most of the metal salts will probably have a limited practical value due to poor thermal stability, low melting points and high hygroscopicity. For example, the dinitramide salts of Li, Na, K, Rb, and Cs all suffer from significant gas losses already at 80°C. 

So far, most interest has been focused on the dinitramide salts of nitrogen bases, particularly ADN. ADN starts to decompose slowly at 85°C. A vacuum stability test showed that 0.88 ml of gas per gram were evolved from a sample over a period of 40 hours. Despite this instability, it has been demonstrated that ADN-based formulations fulfill the military stability requirements at 80°C. However it is unlikely that ADN could be used in any military or commercial applications above its melting point. The rate of decomposition and its autocatalytic behavior conflict with safety considerations. 

A peculiar feature of ADN is that the rate of decomposition increases suddenly by several orders of magnitude at about 60°C when the temperature is being lowered and then decreases again as the temperature continues to go down. This is contrary to an Arrhenius plot for a normal decomposition reaction. No explanation has been found for this behavior. 

The decomposition of ADN can follow at least two different routes. One involves the formation, at 127°C, of ammonium nitrate and N20 [10], followed by a second step, with onset above 200°C, in which the AN decomposes to N02 and water. Potassium dinitramide decomposes with an analogous initial step, forming KNO3. A second route for ADN begins with dissociation of the salt into ammonia and dinitraminic acid, HN(N02)2. This can be viewed as an acid/base equilibrium  

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Traditionally, propellants have consisted of chlorofluorocarbon (CFC) blends (Table 10.3) which have ensured low pulmonary toxicity, high chemical stability and compatibility with packaging materials. The three most widely used CFCs are ... 

Application of liquid crystals as lubricants will require further study in order to assess chemical stability and compatibility relevant to tribological needs. 

From the abovementioned results, it can be concluded that the combination of the partially lluorinated sulfonated ionomer M with the partially fluorinated PBI B2 is of advantage in terms of chemical stability and compatibility, which can be explained with chemical similarity, since both blend components consist of electron-deficient aromatic ring systems. Good PBI blend membrane stabilities can be achieved by good compatibility between the blend components, electron-deficiency of the aromatic ring systems, or both. To get hints of which is the... 

CPA. Copolymer alloy membranes (CPAs) are made by alloying high molecular weight polymeries, plasticizers, special stabilizers, biocides, and antioxidants with poly(vinyl chloride) (PVC). The membrane is typically reinforced with polyester and comes in finished thicknesses of 0.75—1.5 mm and widths of 1.5—1.8 m. The primary installation method is mechanically fastened, but some fully adhered systems are also possible. The CPA membranes can exhibit long-term flexibiHty by alleviating migration of the polymeric plasticizers, and are chemically resistant and compatible with many oils and greases, animal fats, asphalt, and coal-tar pitch. The physical characteristics of a CPA membrane have been described (15). 

Primary expls are the most sensitive of all chemical components in military ammo and hence the most hazardous to handle. Furthermore, single component primary expls are frequently too hazardous to handle and mixts are often used. Before the components of such a mixt are blended, the sensitivity, stability and compatibility must be tested. Reactivity increases with decreasing particle size and increasing intimacy of contact. Because primary expls are so sensitive, not more than 0.5g should be prepd initially. If a compd forms a filter... 

One major drawback of the current methods is the low atom economy45 of solid-supported chemistry with conventional resins in comparison to solution-phase synthesis. The low loadings are one important reason for excluding solid-supported methods from many resource-and cost-sensitive applications such as scale-up projects. Furthermore, polystyrene-based resins are restricted by solvent compatibility, thermal and chemical stability, and extensive adsorption of reagents. 

Minimally, one should have a brief foreknowledge of the thermal and thermal/humidity solid-state stability of the API prior to initiation of excipient compatibility studies. These protocols should include investigation of stability at various temperature and humidity conditions and should always include information about both chemical stability and physical-form integrity of the API. Thermal and thermal moisture-induced solid-state chemical reactions are well known (5), with hydrolysis and oxidation being the most prevalent mechanisms of decay. Changes in physical form with thermal and... 

A majority of the devices for controlled administration of chemicals or drugs employ polymers in their formulation to serve as a vehicle and/or rate controlling element. The purpose of the polymer and the mechanism by which it functions may vary in complexity, but clearly the sorption and diffusion of these chemicals in the polymer is frequently a central issue in product design and function. In addition, environmental stability and compatibility along with mechanical behavior and process-ability are also important issues. Further, these applications place unusual demands on quality control172 of both materials and processes. 

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