Chemical aggressiveness

Exotic materials are less likely to be used in the constmction of hopper cars than in tank cars because of the lower chemical aggressiveness of soHd chemicals compared to that of Hquids and gases. 

Fuels, Lubricants, and Transmission Fluids. Polyol esters of neopentanoic acid have been used as high vacuum pumping hquids that are stable in chemically aggressive environments (70). Esters such as 6- -ani1inophenoxy)hexy1 pivalate are used as antioxidants for synthetic ester lubricants (71). PivaUc anhydride [1538-75-6] has been claimed as an antiknock additive for gasoline (72). 

Extmded engineering thermoplastic stock can be treated like other building material ia that it can be machined, cut, and fastened. However, none of the engineering plastics can be considered a one-for-one substitute for metals or wood. For example, impact resistance must be considered, and glues, paints, etc, must be screened for chemical aggressiveness and adhesion capabiUty. 

For special applications, however, such as for normally humid areas, and contaminated or chemically aggressive locutions, epoxy paints tne con.sidered to be more appropriate. They provide a protective coating which is resistant to chemical fumes, corrosion and temperature. Chlorinated rubber paints, which also fall into the same category of protective paints, may also be used for these areas but, not being temperature resistant, are not preferred to epoxy paints. 

For coating optical devices for use in chemically aggressive environments. 

As reported elsewhere in this article, the polyphosphazene skeleton usually proved to be highly inert to chemical aggressives. Starting from the end of seventies [464, 650] there was a series of papers in which it was clearly... 

The main advantage of the magnesium-air cells is the use of NaCl-electrolyte. This makes the magnesium-air cells environmentally friendly. They are clean, no toxic emission are produced in a way that is safe for user, even for children because the NaCl-electrolyte is not chemically aggressive and magnesium is not toxic. The mechanical recharging of these cells can be accomplished without any chemical danger. 

Chemical aggression, which is translated by a cellular necrosis... 

We are now able to know the intimate nature of the chemical aggression by an irritant or a corrosive on the fragile biological structures of an eye. We can also evaluate the strength of this aggression. 

The amyelinic nervous fibers are to be found in the corneal stroma and also in the superficial epithelium, which is a noticeable ocular specificity. The nervous endings are to be found unconnected between the cells of the superficial epithelium and react with any contact, with chemical aggressions, with drought... 

Any attempt to administer care after an accident or chemical aggression is doomed to failure if it is impossible to remove the aggressive product (or move away from it). 

Food and beverages can be very chemically aggressive milieux and may interact strongly with materials that they touch. Collectively, they are as good as many of the solvents used in a chemistry laboratory. For example, food acids can corrode metals, fats and oils can swell and leach plastics, and beverages can disintegrate unprotected paper and cartonboard. In fact, no food contact material is completely inert and so it is possible for their chemical constituents to... 

Rainwater is essentially free of mineral solutes. It is usually slightly acidic due to the presence of dissolved carbon dioxide, or more highly acidic because of acid rain-forming constituents. As a result of its slight acidity and lack of alkalinity and dissolved calcium salts, rainwater is chemically aggressive toward some kinds of mineral matter, which it breaks down by a process called chemical weathering. 

Accurate self-consistent thermochemical data for the copper chlorides up to 200°C are required, in order to improve solubility calculations and electrochemical modelling capabilities for Aspen Plus and OLI software. Experimental work has been initiated at the University of Guelph, Canada and UOIT to determine a comprehensive thermochemical database, for solubility limits of OMIT, and aqueous cupric chloride versus chloride concentration and temperature using UV-VIS spectroscopy (Suppiah, 2008). The chloride ion is obtained by adding LiCl OMIT. The conditions of tests are primarily 25-200°C, up to 20 bars. Specialised equipment for this task is needed to reach elevated temperatures and pressures, because cupric chloride is chemically aggressive, and because changes in the solution concentrations must be made precisely. A titanium test cell has been custom made, including a UV-VIS spectrometer with sapphire windows, HPLC pumps and an automated injection system. The data acquired will be combined with past literature data for the cuprous chloride system to develop a self-consistent database for the copper (I) and copper (II) chloride-water systems. 

Many fluorinated polymers have been prepared using free-radical processes and the intensity of interest in this field stems from the number of rmique properties that are bestowed on the polymer by the presence of the carbon-fluorine bonds in a system. For example, excellent resistance to chemically aggressive environments, high thermal stability, low dielectric constant, low flammability and very low surface energies are just some of the properties of fluorinated materials that have been exploited. Uses range from... 

Since their mechanical properties are maintained at high temperatures (up to 1700 K), silicon nitride-based materials are attractive for use in high-temperature structural applications in chemically aggressive environments. For example, several properties of a Si3N4-based ceramic (Si3N4-l-SiC+TiN), suitable for ceramic engines, are shown in Table Vm. 

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