Excellent Chemical Stability

Aromatic polyamide (aramid) is of excellent chemical stability and can operate over a pH range of 4.0 to 11.0 at 0 to 35 °C. It is not susceptible to biological attack, but cannot tolerate chlorine. 

The most widely used preservative remains benzalkonium chloride, which often is supplemented with disodium edetate. The benzalkonium chloride defined in the USP monograph is the quaternary ammonium compound alkylbenzyldimethylammonium chloride, in which the alkyl portion is composed of a mixture of chain lengths ranging from C8 to C16. This compound s popularity is based, despite its compatibility limitations, on its being the most effective and rapid-acting preservative with excellent chemical stability. It is stable over a wide pH range and does not... 

Phosphorus oxynitride, PON, is a useful starting product, as a phosphorus and nitrogen source, to prepare various nitridooxophos-phates, in particular phosphorus oxynitride glass compositions (211). Moreover, it shows as a material excellent chemical stability with potential applications in several domains. In microelectronics, for example, PON has been used to form by evaporation insulating films for the passivation of III-V InP substrates and the elaboration of MIS (metal-insulator-semiconductor) structures (190, 212-215). PON could have also valuable properties in flame retardancy (176,191,216). 

With the development of the organic chemical industry, aromatic nitro compounds of the TNT type were introduced as ingredients of composite explosives. TNT is preferable to picric acid since it has no acidic properties and hence is much less reactive. Mixtures with TNT and similar nitro compounds showed an excellent chemical stability. 

The substance is characterized by excellent chemical stability. Its explosive strength, as measured by the expansion produced in the lead block, is equivalent to about 75% of the explosive strength of nitroglycerine. 

UHMWPE possesses a unique combination of mechanical and technological properties and enjoys a variety of special applications based on low friction (solid lubricant), wear resistance (protection of metal surfaces), excellent chemical stability, as well as radiation and neutron resistance. UHMWPE is used in chemical processing, food and beverage industries, foundries, the lumber industry the electrical industry, as medical implants and in mining and mineral processing sewage treatment, and transportation. 

Aromatic and heterocyclic polymers exhibit high glass transitions and excellent chemical stabilities. They were developed for high-temperature applica-... 

Nitroguanidine is soluble in hot water, practically insoluble in cold water, very sparingly soluble in alcohol, insoluble in ether, and readily soluble in alkali. It is not very sensitive to shock or impact. It has excellent chemical stability. 

Very recently, a method to prepare water-soluble CdTe QDs with excellent chemical stability and quantum yields has been developed (Wang et al. 2006). By integrating these water-soluble with our nanoemulsion- or nanoparticle-based... 

Acrylic fibers are hydrophobic with excellent chemical stability. As there are no functional groups present in the acrylics, the fiber producers found... 

Polydivinylbenzene and polystyrene polymer based stationary phases also eliminate these effects. Porous graphitic carbon provides a highly non-polar surface with excellent chemical stability under acidic and basic conditions. However, they suffer from lower sample loading capacity and lower efficiency than conventional columns. 

Timgsten exhibits an excellent chemical stability against cesium vapor at elevated temperature up to 1900°C. This is of importance for the application of tungsten in ionic propulsion systems in spacecrafts. 

FIG. 21 Constitution formula for poly(p-phenylene). The fully aromatic backbone exhibits an excellent chemical stability and has a persistence length of approximately 20 nm. The degree of polymerization used in the studies in Refs. 34, 46 was located between 20 and 40, so that the contour length equals approximately one persistence length at most. The dominant contribution to the signal in small-angle x-ray scattering experiments stems from the iodine ions, since the excess electron density of the backbone is very low. 

Adhesion is due to van der Waals interaction with the surface, and, while polyparylene films exhibit excellent chemical stability, poor adhesion continues to be a major technological problem and limitation. Surface modification techniques, which result in covalent interaction between the polymer film and the surface, might greatly improve adhesion and hence render polyparylene films more protective. 

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