Physical barrier effects

The protection of steel by aluminum coatings depends partly on the physical barrier effect to the coating itself (i.e., exclusion of the environment from the substrate) and partly on sacrificial action. The extent of the latter depends on the environment, the aluminum composition, and the area of steel exposed for example, in the presence of chloride ions, such as during immersion in seawater, aluminum would be fairly active, and the low-resistivity electrolyte would ensure satisfactory protection of the steel by sacrificial action. 

Where, is the area ratio of the total experimental cmwe divided by the total TGA thermogram K is the coefficient of A 7] is the initial experimental temperature (°C), and Tfi the final experimental tenperature (°C). The thermal stability parameter of the TLCP/MWCNT nanocomposites is shown in Table 2. All parameters increased with increasing MWCNT content, indicating that incorporation of MWCNT into the TLCP matrix enhance the thermal stabihty of TLCP/MWCNT nanocomposites. The enhancement of thermal stabihty of the TLCP/MWCNT nanocomposites may be attributed to a physical barrier effect of the MWCNT, which prevented the transport of decomposition in the polymer... 

Separate the metal from the environment with a physical barrier. Many corrosion inhibitors make use of this principal to protect metals. Proper use of an appropriate inhibitor may reduce or eliminate pitting. Pits are frequently initiation sites for corrosion-fatigue cracks. The effectiveness of inhibitors depends upon their application to clean metal surfaces. An example of this method is the use of zinc coatings on steel to stifle pit formation. 

Condoms, which are available for both male and female use, act as physical barriers to prevent pregnancy.44 Condoms are easy to use, available without a prescription, and inexpensive. Most condoms are made of latex. When used correctly, condoms can be very effective in prevention of unwanted pregnancy. Condoms... 

The time factor is the duration of exposure, with the assumption that the shorter the exposure time, the less likely it is that an individual will suffer an ill effect. The distance factor is the physical separation (e.g., in feet or miles) between an individual and the location of the terrorist event. The shielding factor refers to physical barriers between an individual and hazardous substances emanating from the attack location. These three factors are discussed in detail below, along with general rules for minimizing exposure. 

Pauletti GM, Audus KL, Hidalgo U (1998) Effects of co-solvents on the physical barrier properties of Caco-2 cell monolayers. Pharm Sci 1(1) abstract 1182. 

Infusibility thermosets are degraded by heat without passing through the liquid state. This improves some aspects of fire behaviour except for particular cases, they do not drip during a fire and a certain residual physical cohesion provides a barrier effect. 

Silver and silver-copper alloys are often even more sensitive to sulfur compounds—the effect is catalyzed in the presence of oxidizing species and high relative humidity [268]. The resulting surface layer—dark, thin and adherent when developed on a polished surface—usually acts as a good physical barrier that slows down the tarnishing reactions. However, since silver objects are expected to be shiny. 

A variety of beneficial effects have been attributed to sucralfate, but the precise mechanism of action is unclear. It is believed that the negatively charged sucrose sulfate binds to positively charged proteins in the base of ulcers or erosion, forming a physical barrier that restricts further caustic damage and stimulates mucosal prostaglandin and bicarbonate secretion. 

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